INDIVIDUALLY DIRECTED TRAFFIC INDICATION METHOD APPLICABLE TO MULTIPLE LINKS AND RELATED APPARATUS.

Abstract

This application relates to the field of wireless communication and, in particular, to a method of individually addressed traffic indication applicable to multiple links and a related device; for example, this application applies to a wireless local area network compliant with an 802.11be standard. The method includes: A first AP of a first AP MLD generates and transmits individually addressed traffic indication information, where the individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs in a multiple BSSID set in which the first AP is located.This can help some APs or all APs of some AP MLDs to indicate whether station multilink devices associated with the AP MLDs have individually addressed downlink traffic, to help station multilink devices correctly receive individually addressed downlink traffic.

Description

This application claims priority from Chinese patent application no. 202010791117.1, filed with the National Intellectual Property Administration of China on August 7, 2020, entitled INDIVIDUALLY DIRECTED TRAFFIC INDICATION METHOD APPLICABLE TO MULTIPLE LINKS AND RELATED APPARATUS, which is incorporated herein by reference in its entirety. TECHNICAL FIELD OF THE INVENTION This application relates to the field of wireless communication technologies and, in particular, to a method of individually addressing traffic indication applicable to multiple links and a related apparatus. BACKGROUND OF THE INVENTION To significantly increase the transmission speed of services in a wireless local area network (WLAN), the 802.11ax standard from the Institute of Electrical and Electronics Engineers (IEEE) also utilizes Orthogonal Frequency Division Multiple Access (OFDMA) technology, based on existing Orthogonal Frequency Division Multiplexing (OFDM) technology. OFDMA technology supports multiple nodes sending and receiving data simultaneously, achieving multi-station diversity gains. A next-generation Wi-Fi standard, IEEE 802.11be, is known as extremely high throughput (EHT) or Wi-Fi 7, and has a key technical objective: to significantly increase peak throughput. WLAN devices supporting the IEEE 802.11be standard can increase peak throughput and reduce traffic transmission latency by supporting multiple streams (the maximum spatial stream count is 16), multiple frequency bands (e.g., 2.4 GHz, 5 GHz, and 6 GHz), and multiple channels within the same frequency band. These multiple frequency bands or channels can be collectively referred to as multi-links. A next-generation IEEE 802.11 station device that supports multiple links simultaneously is called a multi-link device (MLD). However, some special multi-link access point devices (e.g., all access points (APs) included in multi-link access point devices are APs whose Basic Service Set (Basic) identifiers Service Set Identifier (BSSID) and non-transmitted BSSIDs cannot send beacon frames to indicate whether the station multilink devices (STAs) associated with access point multilink devices have individually addressed downlink traffic. Consequently, the station multilink devices associated with access point multilink devices cannot properly receive individually addressed downlink traffic. Therefore, for some special access point multilink devices (AP MLDs), how to indicate individually addressed downlink traffic has become an urgent problem to solve. BRIEF DESCRIPTION OF THE INVENTION The modalities of this application provide a method for indicating individually addressed traffic applicable to multilinks and related equipment. This can help some or all APs of some AP MLDs to indicate whether station multilink devices associated with the AP MLDs have individually addressed downlink traffic, thus helping station multilink devices to correctly receive individually addressed downlink traffic. The following describes this request from different perspectives. It should be understood that reference can be made to the following implementations and beneficial effects of the different aspects. According to the first aspect, this application provides a method for individually addressable traffic indication applicable to multiple links. The method is applied to a first AP MLD, and a first AP is a reporting AP. The method for individually addressable traffic indication applicable to multiple links includes: The first AP of the first AP MLD generates individually addressable traffic indication information and sends the individually addressable traffic indication information on a first link.Individually Addressed Traffic Indication information is used to indicate whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-broadcasting AP belongs in a multiple BSSID set in which the first AP is located. The first link is a working link of the first AP. Optionally, the reporting AP can be an AP that sends a management frame, where the management frame carries information about multiple APs in a set of AP MLDs co-located from the reporting AP. The management frame is, for example, a beacon frame or a probe response frame. The individually addressed traffic indication information in this solution can not only indicate whether the non-AP MLD associated with the first AP MLD has downlink individually addressed traffic, but it can also help the second AP MLD indicate whether the non-AP MLD associated with the second AP MLD has downlink individually addressed traffic, provided that the second AP MLD is an AP MLD to which a non-broadcasting AP belongs within the multiple BSSID set in which the first AP resides. This can resolve the issue where some or all APs in the AP MLDs cannot indicate whether the non-AP MLDs associated with the AP MLDs have downlink individually addressed traffic, meaning that the non-AP MLDs associated with the APs can normally receive downlink individually addressed traffic. Furthermore, because there is a possibility that all APs in an 802.11be AP MLD are non-transmitting APs, this solution can resolve the problem that AP MLDs whose APs are all non-transmitting APs cannot send individually addressed traffic indications, thereby improving the integrity and diversity of downlink individually addressed traffic indications. With reference to the first aspect, in a possible implementation, the method also includes: The first AP of the first AP MLD generates and sends association identifier (AID) assignment information, where the AID assignment information carries an AID assigned to the non-AP MLD, and the AID is different from an AID of the non-AP MLD associated with the second AP MLD. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, before a first AP of the first AP MLD sends an association response frame, the method further includes: The first AP of the first AP MLD receives an association request frame, where the association request frame is used to request the establishment of a multilink association with the first AP MLD. In this solution, when an AID is assigned, the first AP MLD is considered to help the second AP MLD to indicate whether the non-AP MLD associated with the second AP MLD has individually addressed downlink traffic, so that an AID assigned by the first AP MLD to the non-AP MLD associated with the first AP MLD is different from the AID of the non-AP MLD associated with the second AP MLD, so that AID ambiguity can be avoided when indicating individually addressed downlink traffic. According to a second aspect, this application provides a method for indicating individually addressed traffic applicable to multiple links. The method applies to a non-AP MLD. The method for indicating individually addressed traffic applicable to multiple links includes: A first STA of the non-AP MLD receives individually addressed traffic indication information on a first link on which the first STA operates, and determines, according to the individually addressed traffic indication information received, whether the non-AP MLD has downlink individually addressed traffic.Individually Addressed Traffic Indication Information is used to indicate whether a non-AP MLD associated with a first AP MLD has individually addressed downlink traffic and whether a non-AP MLD associated with a second AP MLD has individually addressed downlink traffic, and the second AP MLD is an AP MLD to which a non-broadcasting AP belongs in a multiple BSSID set in which the first AP is located. Optionally, the reporting AP can be an AP that sends a management frame, where the management frame carries information about multiple APs in a set of AP MLDs co-located from the reporting AP. The management frame is, for example, a beacon frame or a probe response frame. With reference to the second aspect, in a possible implementation, the method also includes: The first STA of the non-AP MLD receives AID assignment information; and analyzes the received AID assignment information, to learn that the AID assignment information carries an AID assigned to the non-AP MLD, where the AID is different from an AID of the non-AP MLD associated with the second AP MLD. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, before the first STA of the non-AP MLD receives an association response frame, the method further includes: The first STA of the non-AP MLD generates and sends an association request frame, where the association request frame is used to request the establishment of a multilink association with the first AP MLD.According to a third aspect, this request provides a communications device.The communications apparatus may be a first AP MLD or a chip in the first AP MLD, such as a Wi-Fi chip, or it may be a first AP of the first AP MLD, and includes: a processing unit, configured to generate individually addressed traffic indication information, where the individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs in a multiple BSSID set in which a first AP is located; and a transceiver unit, configured to send the individually addressed traffic indication information on a first link, where the first link is a working link of the first AP. Optionally, the reporting AP can be an AP that sends a management frame, where the management frame carries information about multiple APs in a set of AP MLDs co-located from the reporting AP. The management frame is, for example, a beacon frame or a probe response frame. With reference to the third aspect, in a possible implementation, the processing unit is further configured to generate AID assignment information, where the AID assignment information carries the AID assigned to the non-AP MLD, and the AID is different from the AID of the non-AP MLD associated with the second AP MLD; and the transceiver unit is further configured to send the AID assignment information. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, the transceiver unit is further configured to receive an association request frame, where the association request frame is used to request the establishment of a multilink association with the first AP MLD. According to a fourth aspect, this application provides a communications apparatus. The communications apparatus may be a non-AP MLD or a chip in the non-AP MLD, such as a Wi-Fi chip, or it may be a first STA of the non-AP MLD and includes: a transceiver unit, configured to receive individually addressed traffic indication information on a first link on which the first STA operates, wherein the individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with a first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs in a multiple BSSID set in which a first AP is located;and a processing unit, configured to determine, according to the individually addressed traffic indication information received, whether the non-AP MLD has downlink individually addressed traffic. Optionally, the reporting AP can be an AP that sends a management frame, where the management frame carries information about multiple APs in a set of AP MLDs co-located from the reporting AP. The management frame is, for example, a beacon frame or a probe response frame. With reference to the fourth aspect, in a possible implementation, the transceiver unit is further configured to receive AID assignment information; and the processing unit is further configured to analyze the received AID assignment information, to learn that the AID assignment information carries an AID assigned to the non-AP MLD, where the AID is different from a non-AP MLD AID associated with the second AP MLD. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, the processing unit is further configured to generate an association request frame; and the transceiver unit is further configured to send the association request frame, where the association request frame is used to request the establishment of a multilink association with the first AP MLD. In any implementation of the above, one bit of the individually addressed traffic indication information corresponds to a non-AP MLD, and one bit of the individually addressed traffic indication information is used to indicate whether a corresponding non-AP MLD has downlink individually addressed traffic. The non-AP MLD here includes the non-AP MLD associated with the first AP MLD and the non-AP MLD associated with the second AP MLD. In any implementation of the above, one bit of the individually addressed traffic indication information corresponds to an Association Identifier (AID), and one bit of the individually addressed traffic indication information is used to indicate whether a non-AP MLD identified by a corresponding AID has downlink individually addressed traffic. The non-AP MLD here includes the non-AP MLD associated with the first AP MLD and the non-AP MLD associated with the second AP MLD. Optionally, individually addressed traffic indication information is carried in a partial virtual bitmap field of a traffic indication map (TIM) element. In this solution, some bits of the TIM element's partial virtual bitmap field are used to indicate whether a non-AP MLD associated with an MLD containing the reporting AP has individually addressed downlink traffic, and whether a non-AP MLD associated with every other AP MLD has individually addressed downlink traffic. Without changing the TIM element's frame format, one AP MLD can help another AP MLD indicate whether a non-AP MLD associated with another AP MLD has individually addressed downlink traffic. This can improve the flexibility of reporting individually addressed downlink traffic. In any of the above implementations, the Association Identifiers (AIDs) corresponding to bits of the individually addressed traffic indication information are different from each other. AID ambiguity can be avoided when indicating whether the non-AP MLD has downlink individually addressed traffic. In an implementation of any of the above aspects, individually addressed traffic indication information includes a TIM block corresponding to the first AP MLD and a TIM block corresponding to a second AP MLD. A TIM block corresponding to the first AP MLD is used to indicate whether the non-AP MLD associated with the first AP MLD has downlink individually addressed traffic, and a TIM block corresponding to a second AP MLD is used to indicate whether a non-AP MLD associated with the second AP MLD has downlink individually addressed traffic. Optionally, individually addressed traffic indication information also includes an index of the second AP MLD, and the second AP MLD indices are in a one-to-one correspondence with the corresponding TIM blocks of the second AP MLD. Optionally, one bit in one of the above TIM blocks corresponds to a non-AP MLD, and one bit in the TIM block is used to indicate whether a corresponding non-AP MLD has individually addressed downlink traffic. Optionally, the AID association identifiers corresponding to bits in the TIM block are different from each other. Optionally, an AID space used by the first AP MLD to assign an AID to the non-AP MLD associated with the first AP MLD and an AID space used by the second AP MLD to assign an AID to the non-AP MLD associated with the second AP MLD are independent of each other. The AID space in this document may alternatively be a set of AIDs to be assigned. In this solution, TIM indication is performed for different deAP MLDs depending on the blocks. This can avoid ambiguity regarding the AIDs of non-AP MLDs associated with the different deAP MLDs. According to a fifth aspect, this request provides a method for assigning an Association Identifier (AID) to a multilink device. The method applies to any AP in a deAP MLD. The method for assigning an AID to a multilink device includes: An AP in a deAP MLD generates and sends AID assignment information, where the AID assignment information carries an AID assigned to a non-AP MLD, the AID is different from an AID of a non-AP MLD associated with a target deAP MLD, and the target deAP MLD is any AP's MLD is any AP's MLD in a set of sets colocated with AP!, or the target AP's MLD is any AP's MLD in a group of sets in which the set of colocated AP's MLD is found. AP! is any AP in the AP's MLD. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, if the target AP MLD is any AP MLD in a colocated AP MLD set of AP1, then both the AP MLD and the target AP MLD belong to the colocated AP MLD set of AP1. If the target AP MLD is any AP MLD in a set group in which the colocated AP MLD set of AP1 is located, then both the AP MLD and the target AP MLD belong to the set group in which the colocated AP MLD set of AP1 is located, and the set group includes the colocated AP MLD set of AP1 and a colocated AP MLD set of any AP other than AP1 in the colocated AP MLD set of AP1. Optionally, before an AP of the AP MLD sends an association response frame, the method further includes: The AP of the AP MLD receives an association request frame, where the association request frame is used to request the establishment of a multilink association with the AP MLD. This solution assumes that the AID of a non-AP MLD associated with the target AP and the AID of the non-AP MLD associated with the target AP MLD must be unique; in other words, they must be different from each other. AID ambiguity can be avoided by specifying whether the non-AP MLD has individually addressed downlink traffic. According to a sixth aspect, this request provides a method for assigning an AID to a multilink device. The method applies to any STA of a non-AP MLD. The method for assigning an AID to a multilink device includes: A STA of a non-AP MLD receives AID assignment information and analyzes the AID assignment information to learn that the AID assignment information carries an AID assigned to the non-AP MLD, where the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a set of AP MLDs colocated by an AP1, or the target AP MLD is any AP MLD in a group of sets in which the colocated AP MLD set of AP1 is located. The AP1 is any AP of the AP MLD. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, if the target AP MLD is any AP MLD in a colocated AP MLD set of AP1, then both the AP MLD and the target AP MLD belong to the colocated AP MLD set of AP1. If the target AP MLD is any AP MLD in a set group in which the colocated AP MLD set of AP1 is located, then both the AP MLD and the target AP MLD belong to the set group in which the colocated AP MLD set of AP1 is located, and the set group includes the colocated AP MLD set of AP1 and a colocated AP MLD set of any AP other than AP1 in the colocated AP MLD set of AP1. Optionally, before the non-AP MLD STA receives an association response frame, the method further includes: The non-AP MLD STA generates and sends an association request frame, where the association request frame is used to request the establishment of a multilink association with the AP MLD. According to a seventh aspect, this request provides a communications apparatus. The communications apparatus can be an AP MLD or a chip in the AP MLD, such as a Wi-Fi chip, and includes: a processing unit, configured to generate AID assignment information, where the AID assignment information carries an AID assigned to a non-AP MLD, the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a co-located AP MLD set of an AP1, or the target AP MLD is any AP MLD in a group of sets in which the co-located AP MLD set of AP1 is located; and a transceiver unit, configured to send the association response frame. The AP1 is any AP of the AP MLD. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, if the target AP MLD is any AP MLD in a colocated AP MLD set of AP1, then both the AP MLD and the target AP MLD belong to the colocated AP MLD set of AP1. If the target AP MLD is any AP MLD in a set group in which the colocated AP MLD set of AP1 is located, then both the AP MLD and the target AP MLD belong to the set group in which the colocated AP MLD set of AP1 is located, and the set group includes the colocated AP MLD set of AP1 and a colocated AP MLD set of any AP other than AP1 in the colocated AP MLD set of AP1. Optionally, the transceiver unit is also configured to receive an association request frame, where the association request frame is used to request the establishment of a multilink association with the AP MLD. According to an eighth aspect, this application provides a communications device. The communications device may be a non-AP MLD or a chip in the A non-AP MLD, such as a Wi-Fi chip, includes: a transceiver unit, configured to receive AID assignment information from an AP of an AP MLD; and a processing unit, configured to analyze the received AID assignment information to learn that the AID assignment information carries an AID assigned to the non-AP MLD, where the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a co-located AP MLD set of an AP1, or the target AP MLD is any AP MLD in a group of sets in which the co-located AP MLD set of AP1 is located. The AP1 is any AP of the AP MLD. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, if the target AP MLD is any AP MLD in a colocated AP MLD set of AP1, then both the AP MLD and the target AP MLD belong to the colocated AP MLD set of AP1. If the target AP MLD is any AP MLD in a set group in which the colocated AP MLD set of AP1 is located, then both the AP MLD and the target AP MLD belong to the set group in which the colocated AP MLD set of AP1 is located, and the set group includes the colocated AP MLD set of AP1 and a colocated AP MLD set of any AP other than AP1 in the colocated AP MLD set of AP1. Optionally, the processing unit is further configured to generate an association request frame; and the transceiver unit is further configured to send the association request frame, where the association request frame is used to request the establishment of a multilink association with the AP MLD. According to a ninth aspect, this application provides a communications apparatus. The communications apparatus is specifically a first AP MLD or a first AP of the first AP MLD and includes a processor and a transceiver. The processor is configured to support the first AP MLD by performing a corresponding function in the preceding method in the first aspect. The transceiver is configured to support communication between the first AP MLD and a non-access point multilink device (also called a station multilink device) and to send information, a frame, a data packet, an instruction, or the like in the preceding method to the station multilink device. The first AP MLD may further include memory. The memory is configured to be coupled to the processor, and the memory stores program instructions and data required by the first AP MLD. Specifically, the processor is configured to generate individually addressed traffic indication information, where the individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs in a multiple BSSID set in which a first AP is located. The transceiver is configured to send the individually addressed traffic indication information on a first link, where the first link is a working link of the first AP. According to a tenth aspect, this application provides a communications apparatus. The communications apparatus is specifically a non-access point multilink device (also called a station multilink device) or a first STA of a non-AP MLD, and includes a processor and a transceiver. The processor is configured to support the station multilink device in performing a corresponding function as described in the preceding method in the second aspect. The transceiver is configured to support communication between the station multilink device and a first AP MLD, and to receive information, a frame, a data packet, an instruction, or the like from the first AP MLD, as described in the preceding method. The station multilink device may further include a memory.The memory is configured to couple to the processor, and the memory stores program instructions and data that are necessary for the station's multi-link device. Specifically, the transceiver is configured to receive individually addressed traffic indication information on a first link where the first STA operates. This individually addressed traffic indication information is used to determine whether a non-AP MLD associated with a first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic. The second AP MLD is an AP MLD belonging to a non-transmitting AP within a multiple BSSID set that includes a first AP. The processor is configured to determine, based on the received individually addressed traffic indication information, whether the non-AP MLD has downlink individually addressed traffic. According to the eleventh aspect, this application provides a communications apparatus. The communications apparatus is specifically an AP MLD or an AP1 AP of the AP MLD, and includes a processor and a transceiver. The processor is configured to support the AP MLD in performing a corresponding function in the preceding method in the fifth aspect. The transceiver is configured to support communication between the AP MLD and a non-access point multilink device (also referred to as a station multilink device) and to send information, a frame, a data packet, an instruction, or the like in the preceding method to the station multilink device. The AP MLD may further include memory. The memory is configured to be coupled to the processor, and the memory stores program instructions and data required by the AP MLD. Specifically, the processor is configured to generate AID assignment information, where the AID assignment information carries an AID assigned to a non-AP MLD. This AID is different from the AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a co-located AP MLD set of an AP1, or any AP MLD in a group of sets in which the co-located AP MLD set of AP1 is located. The transceiver is configured to send the AID assignment information. The AID assignment information is carried in an association response frame. It can be understood that the AID assignment information may alternatively be carried in other frames. The AP1 is any AP in the AP MLD. Optionally, the transceiver is further configured to receive an association request frame, where the association request frame is used to request the establishment of a multilink association with the AP MLD. According to the twelfth aspect, this application provides a communications apparatus. The communications apparatus is specifically a non-access point multilink device (also called a station multilink device) and includes a processor and a transceiver. The processor is configured to support the station multilink device in performing a corresponding function as described in the preceding method in the sixth aspect. The transceiver is configured to support communication between the station multilink device and an AP MLD, and to receive information, a frame, a data packet, an instruction, or the like from the AP MLD, as described in the preceding method. The station multilink device may further include memory. The memory is configured to be coupled to the processor and stores program instructions and data required by the station multilink device. Specifically, the transceiver is configured to receive AID assignment information. The processor is configured to analyze the received AID assignment information to learn that the AID assignment information carries an AID assigned to the non-AP MLD, where the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a set of AP MLDs co-located by an AP1, or the target AP MLD is any AP MLD in a group of sets in which the AP1's co-located set of AP MLDs is located. The AID assignment information is carried in an association response frame. It can be understood that the AID assignment information may alternatively be carried in other frames. The AP1 is any AP in the AP MLD. Optionally, the processor is further configured to generate an association request frame; and the transceiver is further configured to send the association request frame, where the association request frame is used to request the establishment of a multilink association with the AP MLD. According to a thirteenth aspect, this application provides a chip or system-on-a-chip, which includes an input / output interface and a processing circuit. The processing circuit is configured to generate individually addressed traffic indication information, where the individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs in a multiple BSSID set in which a first AP is located. The input / output interface is configured to send the individually addressed traffic indication information on a first link, where the first link is a working link of the first AP. In a possible design, the input / output interface is configured to receive individually addressed traffic indication information on a first link. This individually addressed traffic indication information is used to determine whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic. The second AP MLD is an AP MLD to which a non-broadcasting AP belongs within a multiple BSSID set that includes the first AP. The processing circuit is configured to determine, based on the received individually addressed traffic indication information, whether the non-AP MLD has downlink individually addressed traffic. According to a fourteenth aspect, this request provides a chip or system-on-a-chip, which includes an input / output interface and a processing circuit. The processing circuit is configured to generate AID assignment information, where the AID assignment information carries an AID assigned to a non-AP MLD. This AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a set of AP MLDs co-located by a reporting AP, or the target AP MLD is any AP MLD in a group of sets in which the reporting AP's co-located AP MLD set is located. The input / output interface is configured to send the association response frame. In a possible design, the input / output interface is configured to receive AID assignment information. The processing circuit is configured to analyze the received AID assignment information to learn that the AID assignment information carries an AID assigned to the non-AP MLD, where the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a set of AP MLDs co-located from the reporting AP, or the target AP MLD is any AP MLD in a group of sets in which the AP's co-located AP MLD set is found. According to a fifteenth aspect, this request provides a computer-readable storage medium, and the computer-readable storage medium stores instructions. When the instructions are executed on a computer, the computer is enabled to perform the previously described individually addressed traffic indication method applicable to multiple links according to either the first or second aspect. According to a sixteenth aspect, this application provides a computer-readable storage medium, and the computer-readable storage medium stores instructions. When the instructions are executed on a computer, the computer is enabled to perform the above method for assigning an Association Identifier (AID) to a multi-link device according to the fifth or sixth aspect. According to a seventeenth aspect, the present application provides a computer program product that includes instructions. When the computer program product is run on a computer, the computer is enabled to perform the above individually addressed traffic indication method applicable to multiple links according to either the first or second aspect. According to an eighteenth aspect, this application provides a computer program product that includes instructions. When the computer program product is run on a computer, the computer is enabled to perform the above method for assigning an Association Identifier (AID) to a multilink device according to either the fifth or sixth aspect. Modalities of this request can be implemented to help some APs or all APs of some AP MLDs to indicate whether station multilink devices associated with the AP MLDs have individually addressed downlink traffic, to help station multilink devices correctly receive individually addressed downlink traffic. BRIEF DESCRIPTION OF THE DRAWINGS To describe more clearly the technical solutions of the modalities of this application, the attached drawings used to describe the modalities are briefly described below. FIGURE 1 is a schematic diagram of the structures of an AP MLD and a MLD of non-AP according to a modality of this application; FIGURE 2 is a schematic diagram of a TIM element frame format according to one modality of this application; FIGURE 3 is a schematic diagram of a single-element grid format. Multiple BSSIDs according to a modality of this request; FIGURE 4a is a schematic diagram of a 100 communication according to one modality of this request; FIGURE 4b is a schematic diagram of a 200 communications according to one modality of this request; FIGURE 4c is a schematic diagram of a 300 communications according to one modality of this request; structure of a system FIGURE 5 is a schematic diagram of an architecture of a plurality of multiple BSSID sets according to a modality of this application; FIGURE 6 is a schematic flowchart of an individually directed traffic indication method applicable to multiple links according to one modality of this application; FIGURE 7 is a schematic diagram of a partial virtual bitmap field according to one modality of this request; FIGURE 8 is a schematic diagram of a partial raster format of a new item according to a modality of this application; FIGURE 9 is a schematic flowchart of a method for assigning an AID to a non-AP MLD according to a modality of this request; FIGURE 10a is a schematic diagram of a set of AP MLDs colocated from an AP according to a modality of this application; FIGURE 10b is another schematic diagram of a set of AP MLDs colocated from an AP according to a modality of the present application; FIGURE 10c is another schematic diagram of a set of AP MLDs colocated from an AP according to a modality of the present application; FIGURE 11 is a schematic diagram of a frame format of an AID element according to one modality of this application; FIGURE 12 is another schematic flowchart of an individually directed traffic indication method applicable to multiple links according to one modality of this application; FIGURE 13 is a schematic diagram of a communications apparatus structure 1 according to one modality of this application; FIGURE 14 is a schematic diagram of a communications apparatus structure 2 according to one modality of this application; FIGURE 15 is a schematic diagram of a communications apparatus structure 3 according to one modality of this application; FIGURE 16 is a schematic diagram of a communications apparatus structure 4 according to one modality of this application; and FIGURE 17 is a schematic diagram of a structure of a 1000 communications apparatus according to one modality of this application. DESCRIPTION OF MODALITIES The technical solutions in the forms of this application are clearly described below with reference to the drawings attached to the forms of this application. To better understand an individually directed traffic indication method applicable to multiple links and a related apparatus described in the modalities of this application, the related concepts in the modalities of this application are first described. 1. Multi-link device A wireless communications system to which the modalities of this application apply can be a wireless local area network (WLAN) or a cellular network, and the individually addressed traffic indication method can be implemented by a communications device in the wireless communications system or by a chip or processor in the communications device. The communications device can be a wireless communications apparatus that supports multiple links for parallel transmission and is, for example, called a multi-link device (MLD) or multi-band device. Compared to a device that only supports single-link transmission, the multi-link device has higher transmission efficiency and higher throughput. A multi-link device includes one or more affiliated stations (STAs). An affiliated station is a logical station that can operate on a link. The affiliated station can be an access point (AP) or a non-access point station (Non-AP STA). For ease of description, a multi-link device whose affiliated station is an AP in this application may be referred to as a multi-link AP or multi-link AP device. AP MLD). A multi-link device whose affiliated station is a non-AP STA may be referred to as a non-AP multi-link device or non-AP multi-link device (Non-AP MLD). For ease of description, a multi-link device that includes an affiliated station is also briefly described as a multi-link device that includes a station in the modalities of this application. A multilink device includes one or more affiliated stations (STAs). In other words, a multilink device can include multiple logical stations. Each logical station operates on one link, but multiple logical stations are allowed to operate on the same link. The multi-link device can implement wireless communication according to the 802.11 family of standards. For example, a station that meets Extremely High Throughput (EHT) standards, or a station that complies with 802.11be, or is compatible with another station that supports 802.11be, implements communication with another device. This other device may or may not be a multi-link device. For example, the multilink device in this application modality can be a single-antenna device or a multi-antenna device. For example, the device can have more than two antennas. The number of antennas included in the multilink device is not limited in this application modality. In certain applications, the multilink device may allow the transmission of services of the same access type over different links, and even allow the transmission of the same data packet over different links; or it may not allow the transmission of services of the same access type over different links, but may allow the transmission of services of different access types over different links. For example, a multi-link device is an appliance with a wireless communication function. The appliance can be a complete device, or it can be a chip, processing system, or similar component installed throughout the device. A device in which the chip or processing system is installed can implement the methods and functions of the modes described in this application under the control of the chip or processing system. For example, a non-AP MLD in the modes described in this application has a wireless transceiver function, which can be compatible with the 802.11 series protocols and can communicate with an AP MLD, another non-AP MLD, or a single-link device. For example, an STA MLD is any user communications appliance that allows a user to communicate with an AP and then communicate with the WLAN.For example, a non-AP MLD can be a user device that can connect to the internet, such as a tablet, desktop computer, laptop, notebook computer, ultra-mobile personal computer (UMPC), handheld computer, netbook, personal digital assistant (PDA), or mobile phone, or an Internet of Things node in the Internet of Things, a vehicle-mounted communications device in the Internet of Vehicles, or similar. Alternatively, a non-AP MLD can be a chip and processing system within these terminals. The AP MLD in the modalities of this application is a device that provides a service to the non-AP MLD and can support the 802.11 series protocols. For example, the AP MLD can be a communications entity, such as a communications server, router, switch, or network bridge, or it can include a macro base station, micro base station, relay node, and similar devices in various forms. The AP MLD can also be a chip and processing system within these devices in various configurations, thereby implementing the methods and functions of the modalities in this application. Furthermore, the multilink device can support high-speed, low-latency transmissions.With the continuous evolution of application scenarios for wireless local area networks, the multi-link device can alternatively be applied to more scenarios, such as sensor nodes (such as smart water meters, smart energy meters, and smart air detection nodes) in smart cities, smart devices (such as smart cameras, projectors, display screens, televisions, stereos, refrigerators, and washing machines) in smart homes, nodes in the Internet of Things, entertainment terminals (such as AR, VR, and other wearable devices), smart devices (such as printers and projectors) in smart offices, the Internet of Devices in Vehicles, and some infrastructure (such as vending machines, self-service navigation counters in supermarkets, self-service checkouts, and self-service ordering machines) in everyday life scenarios.The specific forms of the non-AP MLD and the AP MLD are not particularly limited in the modalities of this application and are only an example for the purposes of this document. The 802.11 protocol can be a protocol that supports 802.11be or is compatible with 802.11be. The frequency bands in which the multi-link device operates may include, among others, sub-1 GHz, 2.4 GHz, 5 GHz, 6 GHz and 60 GHz high frequency. For example, the multilink device in this modality of this application can be a single-antenna device or a multi-antenna device. For example, the multilink device in the modalities of this application can be a device with two or more antennas. The number of antennas included in the multilink device is not limited in this modality of this application. Figure 1 is a schematic diagram of the structures of an AP MLD and a non-AP MLD according to one modality of this application. Figure 1 is a schematic diagram of the structure of an AP MLD with multiple antennas and a non-AP MLD with a single antenna. An 802.11 standard focuses on a portion of the Physical Layer (PHY) and a portion of the Media Access Control (MAC) layer in the AP MLD and the non-AP MLD. 2. Link identifier The link identifier represents a station operating on a link. In other words, if there is more than one station on a link, more than one link identifier represents the stations. A link mentioned below sometimes also represents a station operating on the link. When data is transmitted between an AP MLD and a non-AP MLD, a link identifier can be used to identify a link or a station on a link. Before communication, the AP MLD and the non-AP MLD can negotiate or communicate a mapping between a link identifier and a link or station on a link. Therefore, during data transmission, a link identifier is carried without the need to transmit a large amount of signaling information to indicate a link or station on a link. This reduces signaling overhead and improves transmission efficiency. In one example, a management frame, such as a beacon frame, sent by the AP's MLD when establishing a basic service set (BSS) carries an element, and this element includes multiple link identification information fields. The link identification information field can indicate a correspondence between a link identifier and a station operating on a link corresponding to that link identifier. The link identification information field includes not only the link identifier but also one or more of the following: a Media Access Control (MAC) address, an operation set, and a channel number. One or more of the MAC address, the operation set, and the channel number can identify a link. For an AP, the AP's MAC address is also its BSSID (basic service set identifier).In another example, during a multi-link device association process, the AP MLD and the non-AP MLD negotiate over multi-link identification information fields. Multi-link device association means that an AP from the AP MLD is associated with a STA from the non-AP MLD once, and this association can then allow multiple STAs from the non-AP MLD to associate with multiple APs from the AP MLD, where one STA is associated with one AP. In subsequent communication, the AP MLD or the non-AP MLD uses a link identifier to represent a station on the non-AP MLD. This link identifier can also represent one or more attributes of a station's MAC address, a set of operations, and a channel number. The MAC address can be replaced with an AP MLD association identifier after association. Optionally, if multiple stations are working on a link, a link identifier (which is a digital ID) includes not only a set of operations containing a link and a channel number, but also an identifier for a station working on the link, such as a station's MAC address or association identifier (AID). 3. Traffic indication map element A traffic indication map (TIM) beacon frame and a delivery traffic indication map (DTIM) beacon frame each carry a traffic indication map (TIM) element. Figure 2 is a schematic diagram of a frame format for a TIM element according to one modality of this application. As shown in Figure 2, a frame format for a TIM element field includes: Element identifier field (identifier, ID): used to identify an element shown in FIGURE 2 as a TIM element. Length field: Used to indicate the length of the TIM element and to collect statistics on the total length after the field, to be specific, the total length of a DTIM count field, a DTIM period field, a bitmap control field and a partial virtual bitmap field, in units of bytes. DTIM Count field: This field indicates how many TIM beacon frames appear before the arrival of the next DTIM beacon frame from the current beacon frame that carries the TIM element. In other words, the DTIM count field is a count value, and the count value is variable. When the DTIM count field value is 0, it indicates that the current beacon frame is a DTIM beacon frame. When the DTIM count field value is not 0, it indicates that the current beacon frame is a TIM beacon frame. DTIM Period Field: This field is used to indicate the duration of the DTIM beacon frame period, in other words, an arrival interval, where the arrival interval is one unit of a TIM beacon frame period. For example, if a DTIM period is set to 1, the DTIM count in each TIM element field is equal to 0; in other words, each beacon frame is a DTIM beacon frame. Bitmap control field: As shown in FIGURE 2, a 0 bit in the bitmap control field is used to indicate whether an access point (AP) forwards group-addressed data traffic after sending a DTIM beacon frame. In other words, the 0 bit in the bitmap control field in the DTIM beacon frame indicates whether the AP caches group-addressed traffic, and the group-addressed traffic is not sent through a group-addressed AID. Bits 1 through 7 in the bitmap control field are used to indicate an offset of a partial virtual bitmap, and the offset is one byte (i.e., 8 bits). Partial virtual bitmap: Each bit in the partial virtual bitmap field corresponds to an association identifier (AID) and is used to indicate whether a station corresponding to that AID has individually addressed traffic. Alternatively, each bit in the partial virtual bitmap field corresponds to a group-addressed AID and is used to indicate whether a group of stations corresponding to a group-addressed AID has individually addressed downlink traffic. The partial virtual bitmap field consists of some bits from a traffic indication virtual bitmap field, where the traffic indication virtual bitmap field is 251 bytes, and is used to indicate whether stations corresponding to AID 0 through AID 2007 have individually addressed downlink traffic. Each element ID field, length field, DTIM count field, DTIM period field, and bitmap control field occupy one byte. 4. Multiple Basic Service Set Identifiers (Multiple BSSID Set) A Multiple Basic Service Set Identifiers (Multiple BSSID Set, which may be referred to as a Multiple BSSID Set) can be understood as a set of cooperating access points (APs). All cooperating access points use the same set of operations, channel number, and antenna interface. In the Multiple BSSID Set, only one AP has a transmitted BSSID, while the other APs have non-transmitted BSSIDs. Multiple BSSID Set information (i.e., a Multiple BSSID element) is carried in a beacon frame, probe response frame, or neighbor report sent by an AP with a transmitted BSSID.Information about an AP's BSSID with the untransmitted BSSID is derived by a station based on the beacon frame or probe response frame, or a multiple BSSID element in the neighbor report, or similar. The BSSID of the AP with the untransmitted BSSID is calculated based on the AP's BSSID with the transmitted BSSID and a BSSID index field in a multiple BSSID index element in a non-transmitted BSSID profile of the AP's BSSID with the untransmitted BSSID. For a specific method, see the 802.11 REVmd_D3.0 protocol draft. The multiple BSSID set can be understood as including multiple APs. Each AP manages a BSS, and different APs can have different SSIDs and permissions, such as security mechanisms or broadcast opportunities. In a multi-BSSID set, only an AP with a broadcast BSSID can send a beacon frame and a probe response frame, while an AP with a non-broadcast BSSID does not send a beacon frame. Therefore, if a probe request frame sent by a STA is sent to an AP in the multi-BSSID set with a non-broadcast BSSID, an AP in the multi-BSSID set with a broadcast BSSID will respond by sending a probe response frame. A BSSID of one of the multiple APs in the multiple BSSID set is configured as a Transmitted BSSID, and the AP with the Transmitted BSSID can be called a Transmitted AP; the BSSIDs of the other APs are configured as Non-transmitted BSSIDs, and the APs with the Non-transmitted BSSID can be called Non-transmitted APs. A beacon frame sent by the transmitting AP can include a multiple BSSID element, and a frame format for the multiple BSSID element is shown in Figure 3. Figure 3 is a schematic diagram of a frame format for a multiple BSSID element according to one modality of this application. The multiple BSSID element includes an element ID field, a length field, a maximum BSSID indicator field, and an optional subelement field. The maximum BSSID indicator field is used to indicate a maximum number N of BSSIDs included in the multiple BSSID set, and the optional subelement field includes information about an AP with a non-transmitted BSSID. The maximum number of APs allowed in the multiple BSSID set is 2^n, where n is a value indicated by the MaxBSSID indicator field in the multiple BSSID element shown in Figure 3, and N = 2^n. Therefore, bits 1 through 2^n-1 of the traffic indication virtual bitmap field can be assigned to APs with non-transmitted BSSIDs in the multiple BSSID set to indicate whether those APs with non-transmitted BSSIDs whose NonTxBSS IDs (identifiers) are 1 through 2^n-1 have group-directed traffic. A NonTxBSS ID value is equal to a value in the BSSID index field in the multiple BSSID index element of the non-transmitted BSSID profile within the multiple BSSID element. The non-transmitted BSSID profile is located in the optional sub-element field. Although the features of this application are described primarily using a network implementing IEEE 802.11 as an example, a person skilled in the art will readily understand that several aspects of this application can be extended to other networks using various standards or protocols, such as Bluetooth, a high-performance radio LAN (HIPERLAN) (a wireless standard similar to IEEE 802.11 and used primarily in Europe), a wide area network (WAN), a wireless local area network (WLAN), a personal area network (PAN), or other networks currently known or that may be developed in the future. Therefore, the various aspects provided in this application are applicable to any suitable wireless network regardless of coverage and wireless access protocol. Figure 4a is a schematic diagram of a communication system 100 structure according to one modality of this application. In Figure 4a, a wireless local area network is used as an example to describe the communication system 100 applied to this modality of the application. The communication system 100 includes station 101 and station 102. Station 101 and station 102 can use multiple links for communication, achieving the effect of improved performance. Station 101 can be a multi-link device, and station 102 can be a single-link device, a multi-link device, or similar. In one scenario, station 101 is an AP MLD, and station 102 is a non-AP MLD or a station (such as a single-link station). In another scenario, station 101 is a non-AP MLD, and station 102 is an AP (such as a single-link AP) or an AP MLD.In another scenario, station 101 is an AP MLD and station 102 is either an AP MLD or an AP; in yet another scenario, station 101 is a non-AP MLD, and station 102 is either a non-AP MLD or a STA (such as a single-link station). Certainly, the wireless local area network may also include other devices. The number and types of devices shown in Figure 4a are merely examples. Figure 4b is a schematic diagram of a communication system 200 structure according to one modality of this application. Figure 4c is a schematic diagram of a communication system 300 structure according to one modality of this application. Figure 4b or Figure 4c are schematic diagrams of communication system 200 and communication system 300 structures, respectively. Communication system 200 and communication system 300 are described using an example in which a multi-link device in the wireless local area network communicates with other devices through multiple links. Specifically, FIGURE 4b shows a communication scenario between an AP MLD and a non-AP MLD. The AP MLD includes an affiliated AP 1 and an affiliated AP 2, the non-AP MLD includes an affiliated STA 1 and an affiliated STA 2, and the AP MLD and the non-AP MLD communicate through a link 1 and a link 2 in parallel. Figure 4c shows a scenario in which an AP 601 MLD communicates with a non-AP 602 MLD, a non-AP 603 MLD, and a STA604. The AP 601 MLD includes an AP 6011 affiliated with an affiliated AP 601-3. The non-AP 602 MLD includes three affiliated stations: one STA 602-1, an STA 602-2, and an STA 602-3. The non-AP MLD 603 includes two affiliated stations: an STA 603-1 and an STA 603-2. STA 604-1 and STA 604 are single-link devices. The AP MLD 601 can communicate separately with the non-AP MLD 602 ​​via link 1, link 2, and link 3, communicate with the non-AP MLD 603 via link 2 and link 3, and communicate with STA 604 via link 1. In one example, STA 604 operates in a 2.4 GHz band; in the non-AP MLD 603, STA 603-1 operates in a 5 GHz band and STA 603-2 operates in a 6 GHz band; In the noAP602 MLD, STA 6021 operates in the 2.4 GHz band, STA 602-2 operates in the 5 GHz band, and STA 602-3 operates in the 6 GHz band. Uplink or downlink data can be transmitted between AP 601-1, which operates in the 2.4 GHz band in the AP 601 MLD, and STA 604 and STA 602-1 in the noAP 602 MLD via link 1.Uplink or downlink data can be transmitted between AP 601-2, operating in the 5 GHz band on AP 601's MLD, and STA 603-1, operating in the 5 GHz band on non-AP 603's MLD, via link 2. Additionally, uplink or downlink data can be transmitted between AP 601-2 and STA 602-2, both operating in the 5 GHz band on non-AP 602's MLD, via link 2. Uplink or downlink data can also be transmitted between AP 601-3, operating in the 6 GHz band on AP 601's MLD, and STA 602-3, operating in the 6 GHz band on non-AP 602's MLD, via link 3. Furthermore, uplink or downlink data can be transmitted between AP 601-3 and STA 602-3. 603-2 in the non-AP MLD through link 3. Figure 4b shows only one example where the AP MLD supports two frequency bands, and Figure 4c shows only one example where the AP MLD 601 supports three frequency bands (2.4 GHz, 5 GHz, and 6 GHz). Each frequency band corresponds to a link, and the AP MLD 601 can operate on one or more links of Link 1, Link 2, or Link 3. On the AP or STA side, the link in this document can also be understood as a station operating on the link. In practical applications, the AP MLD and the non-AP MLD can support more or fewer frequency bands; that is, the AP MLD and the non-AP MLD can operate on more or fewer links. This is not limited by the modalities of this application. Figure 5 is a schematic diagram of an architecture with a plurality of multiple BSSID sets according to a modality of this application. In other words, the AP MLDs shown in Figure 5 are a collocated AP MLD set. BSSID-lx, BSSID-1y, BSSID-2x, BSSID-2y, BSSID-2z, BSSID-4x, BSSID-4y, BSSID-4z, BSSID-3, and BSSID-5 are MAC address identifiers used to identify corresponding access points (APs). An AP whose MAC address identifier ends with "x" is assumed to be a broadcast BSSID AP, an AP whose MAC address identifier ends with "yoz" is a non-broadcast BSSID AP, and an AP whose MAC address identifier ends with only a number is a common AP. A common AP is an AP that does not belong to a multiple BSSID set.For example, an AP with BSSID broadcast in a multiple BSSID set 1 is an AP 1x whose MAC address identifier is BSSID_1x, an AP with BSSID not broadcast in multiple BSSID set 1 is an AP 1y whose MAC address identifier is BSSID_1y, an AP with BSSID broadcast in a multiple BSSID set 2 is an AP 2x whose MAC address identifier is BSSID_2x, and APs with BSSID not broadcast in multiple BSSID set 2 include an AP 2y whose MAC address identifier is BSSID_2y and an AP 2z whose MAC address identifier is BSSID_2z. A reporting AP's co-located AP MLD set includes the following APs, where the reporting AP is an AP that sends a management frame, and the management frame carries information about the following multiple APs. The management frame is, for example, a beacon frame or a probe response frame. The reporting AP includes a transmitting AP and a common AP within a BSSID set. The reporting AP's co-located AP MLD set includes the following APs: (1) all APs that belong to the same AP MLD as the reporting AP, or all APs in the AP MLD in which the reporting AP is located; (2) all APs in an AP MLD in which there is a non-broadcasting AP in the same set of multiple BSSIDs as the reporting AP (or broadcasting AP); or all APs in an AP MLD in which there is a non-broadcasting AP in a set of multiple BSSIDs in which the reporting AP (or broadcasting AP) is located; and (3) all APs in an AP MLD that meet the following two conditions, where the two conditions are: 1) at least one AP in the AP MLD is in the same set of multiple BSSIDs as an AP in the AP MLD in which the reporting AP is located; and 2) there is no AP in the AP MLD that operates on the same link as the reporting AP. Optionally, in one implementation, an AP MLD includes only one AP. Optionally, the reporting AP can be a common AP in an AP MLD (such as AP 3 whose MAC address identifier is BSSID 3 and AP 5 whose MAC address identifier is BSSID 5 in FIGURE 5) or a broadcast AP in a multiple BSSID set, and can send the individually addressed traffic indication information described in this application. For example, AP 1x in FIGURE 5 is used as the reporting AP, and then the APs included in the co-located AP MLD set of AP 1x include: (1) all APs in the same MLD as AP 1 and AP 1x, namely AP 1x, AP 2y and AP3; (2) all APs in an AP MLD 3 in which a non-transmitting AP (i.e., AP 1y) is in the same multiple BSSID set 1 as AP 1x, i.e., AP 1y, AP 2z and an AP 4y; and (3) AP 2x and an AP 4x included in an AP MLD that satisfies the above conditions 1) and 2) in FIGURE 5, namely an AP MLD 2, wherein AP 2x in AP MLD 2 and AP 2y in AP MLD 1 are in the same multiple BSSID set 2, and no AP in AP MLD 2 is on the same link as AP 1x. In a multi-BSSID set, only an AP with a broadcast BSSID can send a beacon frame and a probe response frame, while an AP with a non-broadcast BSSID does not send a beacon frame. Therefore, if all APs in an AP MLD (e.g., AP MLD 3 in Figure 5) are non-broadcast access points, and because a TIM element is carried in a beacon frame, the AP MLD cannot indicate whether a non-AP MLD associated with the AP MLD has individually addressed downlink traffic. Furthermore, for another example, in AP MLD 1 in Figure 5, AP 2, operating on link 2, is a non-broadcast AP. A non-AP MLD operating on link 2 cannot receive notification of individually addressed downlink traffic sent to the non-AP MLD by AP MLD 1, which is associated with the non-AP MLD. Therefore, the modalities in this application provide a method for indicating individually addressed traffic applicable to multiple links. An indication of downlink individually addressed traffic from an AP MLD to which a non-transmitting AP belongs is carried in the signaling sent by a reporting AP. This can help the AP MLD to which the non-transmitting AP belongs to indicate whether a non-transmitting AP MLD associated with the AP MLD has downlink individually addressed traffic. The technical solutions provided in this application are described in detail below with reference to the accompanying drawings. One or more APs in an AP MLD need to send buffer unit (BU) indication information to non-AP MLDs associated with one or more APs, and one bit of the BU indication information corresponds to an AID of a non-AP MLD. If a bit of the BU indication information is set to 1, it indicates that the AP MLD has individually addressed downlink traffic for the non-AP MLD identified by the AID corresponding to the bit; or if a bit of the BU indication information is set to 0, it indicates that the AP MLD does not have individually addressed downlink traffic for the non-AP MLD identified by the AID corresponding to the bit. Establishing a multi-link partnership: In the process of establishing a multi-link association, a station in a station MLD and an access point (AP) in an AP MLD interact via an association request frame or an association response frame to establish a multi-link association. Specifically, each of the multiple stations in the station MLD establishes an association with each of the multiple APs in the AP MLD. In an association response frame sent by an AP in an AP MLD, an Association ID (AID) is assigned to each station MLD; in other words, multiple stations in the station MLD share the same AID. The AP MLD and the station MLD each have a unique MLD MAC address. The MLD MAC address is an index used at a higher MAC layer, such as a source and destination for IP data. In other words, data packets sent by each AP in the AP MLD to the same station MLD are shared. Mode 1 Figure 6 is a schematic flowchart of an individually addressed traffic indication method applicable to multiple links, as per a modality of this application. The individually addressed traffic indication method applicable to multiple links is described using an example in which the method is implemented in a communications system that includes an AP MLD and a non-AP MLD. The AP MLD includes one or more APs, and a first AP is any reporting AP of the AP MLD. Optionally, the non-reporting AP is a non-transmitting AP in a set of multiple BSSIDs. The non-AP MLD includes one or more STAs, and a first STA is any STA of the non-AP MLD. As described above, a multilink association can be established between the AP MLD and the non-AP MLD, with both the first AP and the first STA operating on the first link.As shown in FIGURE 6, the individually directed traffic indication method applicable to multiple links includes but is not limited to the following steps. S101: The first AP of a first AP MLD generates individually addressed traffic indication information, where the individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-broadcasting AP belongs in a multiple BSSID set in which the first AP is located. Individually addressed traffic indication information may be called an individually addressed traffic indication field, an individually addressed traffic indication, or a buffer unit (BU) indication. This is not limited in this application. Individually addressed traffic indication information may be carried in a TIM element, for example, the TIM element field shown in Figure 2, and the individually addressed traffic indication information is carried in a partial virtual bitmap field. Specifically, the first AP is a reporting AP in the multiple BSSID set, and the first AP belongs to the first AP MLD. Therefore, the first AP of the first AP MLD can generate individually addressed traffic indication information, and the individually addressed traffic indication information can include two parts of indication information.Part of the indication information is individually addressed traffic indication information from the first AP MLD, and is used to indicate whether the non-AP MLD associated with the first AP MLD has downlink individually addressed traffic; the other part of the indication information is individually addressed traffic indication information from the AP MLD (i.e., the second AP MLD) to which a non-broadcasting AP belongs in a multiple BSSID set in which the first AP is located, and is used to indicate whether a non-AP MLD associated with the second AP MLD in the first link on which the first AP works has downlink individually addressed traffic.In other words, individually addressed traffic indication information carries not only the individually addressed traffic indication of the reporting AP (the first AP), but also an individually addressed traffic indication from an AP MLD to which other non-broadcasting APs belong within the multiple BSSID set in which the reporting AP is located. It can be understood that the individually addressed traffic indication information mentioned in this request includes two parts of indication information, and this does not mean that the two parts of indication information are in different fields; they can be in the same field. Optionally, there are the following two possibilities for the non-AP MLD associated with the MLD in which the reporting AP is located: 1) all non-AP MLDs that establish multi-link associations with the MLD in which the reporting AP is located, where the non-AP MLD can establish associations with some or all of the APs in the MLD in which the reporting AP is located; or 2) a non-AP MLD associated with the reporting AP in the MLD in which the reporting AP is located, where the non-AP MLD can establish associations with some or all of the APs in the MLD in which the reporting AP is located, provided that some or all of the APs need to include the reporting AP. Optionally, there are also the following two possibilities for the non-AP MLD associated with the AP MLD to which the non-transmitting AP belongs in the multiple BSSID set in which the reporting AP is located: 1) The non-AP MLD can indicate all the 1) non-AP MLDs that establish multilink associations with the AP MLD to which the non-transmitted AP belongs, where the non-AP MLDs can establish associations with some or all of the APs of the AP MLD to which the non-transmitted AP belongs; or 2) the non-AP MLD can indicate a non-AP MLD associated with the non-transmitted AP of the AP MLD to which the non-transmitted AP belongs, where the non-AP MLD can establish associations with some or all of the APs of the AP MLD to which the non-transmitted AP belongs, provided that some or all of the APs need to include the non-transmitted AP. For example, in FIGURE 5, AP 1x, whose MAC address identifier is BSSID_1x, is used as the reporting AP; in other words, the first AP is AP 1x. Therefore, the MLD of AP 1 in FIGURE 5 is the first AP MLD, and a link on which AP 1x operates is link 1.The individually addressed traffic indication information generated by AP 1x includes the individually addressed traffic indication, for the non-AP MLD associated with the MLD in which AP 1x is located, of AP 1x, and there are the following two possibilities: 1) The individually addressed traffic indication information can indicate whether all non-AP MLDs that establish multilink associations with the AP 1 MLD have downlink individually addressed traffic, where the non-AP MLDs can establish associations with some or all of the APs in the AP 1 MLD; or 2) the individually addressed traffic indication information can indicate whether a non-AP MLD associated with AP 1x in the AP 1 MLD has downlink individually addressed traffic, where the non-AP MLD can establish associations with some or all of the APs in the AP 1 MLD, provided that some or all of the APs need to include AP 1x.The individually addressed traffic indication information generated by AP 1x also includes an individually addressed traffic indication, for a non-AP MLD associated with AP 3's MLD, from AP 3's MLD to which the non-transmitting AP (i.e., AP 1y) belongs in the multiple BSSID set 1 in which AP 1x is located, and there are also the following two possibilities: 1) The individually addressed traffic indication information can indicate whether all non-AP MLDs associated with AP 3's MLD have downlink individually addressed traffic; or 2) the individually addressed traffic indication information can indicate whether a non-AP MLD associated with AP 1y, from AP 3's MLD, in the same multiple BSSID set as AP 1x, has downlink individually addressed traffic.For example, a non-AP MLD 1 is associated with AP 1y of AP MLD 3 on link 1 and AP 2z of AP MLD 3 on link 2, a non-AP MLD 2 is associated with AP 1y of AP MLD 3 on link 1, AP 2z of AP MLD 3 on link 2 and AP 4y of AP MLD 3 on link 4, and a non-AP MLD 3 is associated with AP 2z of AP MLD 3 on link 2 and AP 4y of AP MLD 3 on link 4. In a first implementation, the indication of individually addressed traffic from AP MLD 3 to the non-AP MLD associated with AP MLD 3 includes indicating whether non-AP MLD 1, non-AP MLD 2 and non-AP MLD 3 have downlink individually addressed traffic. In a second implementation, the indication of individually addressed traffic from AP 3 MLD to the non-AP MLD associated with AP 3 MLD includes indicating whether non-AP MLD 1 and non-AP MLD 2 have individually addressed downlink traffic. For another example, AP 2x, whose MAC address identifier is BSSID_2x, is used as the reporting AP; in other words, the first AP is AP 2x. Then, the MLD of AP 2 in FIGURE 5 is the first AP MLD, and a link on which AP 2x operates is link 2. The individually addressed traffic indication information generated by AP 2x includes not only the individually addressed traffic indication for the non-AP MLD associated with the MLD in which AP 2x is located, from AP 2x, but also an individually addressed traffic indication for a non-AP MLD associated with the MLD of AP 1 to which AP 2y belongs, from the MLD of AP 1, and an individually addressed traffic indication for a non-AP MLD associated with the MLD of AP 3 to which AP 2z belongs, from the MLD of AP 3. In an optional mode, the reporting AP herein may not be limited to an AP of an AP MLD; specifically, the reporting AP herein may be a single-link device. The individually addressed traffic indication information generated by the reporting AP carries an individually addressed traffic indication, for a station associated with the reporting AP, from the reporting AP, which is used to indicate whether the station associated with the reporting AP has downlink individually addressed traffic; and may also carry an individually addressed traffic indication from an AP MLD to which other non-broadcasting APs belong in the current link's multiple BSSID set, which is used to indicate whether the AP MLD has downlink individually addressed traffic for a non-AP MLD associated with the AP MLD. S102: The first AP of the first AP MLD sends individually addressed traffic indication information on a first link, where the first link is a working link of the first AP. In this form of this application, the individually addressed traffic indication information can be carried in a management frame, such as a beacon frame or a TIM frame; or the individually addressed traffic indication information can alternatively be carried in another frame, such as a data frame or a control frame. S103: The first STA of the non-AP MLD receives individually addressed traffic indication information on the first link on which the first STA works. The first STA can be a station managed by the first AP or a station surrounding the first AP. The surrounding stations of the first AP include a station managed by the first AP and a non-associated station. The individually addressed traffic indication method described in this application uses the AP-managed station as an example. Optionally, the first STA can be any station in the non-AP MLD and can learn whether the non-AP MLD to which the first STA belongs has downlink individually addressed traffic. Optionally, both the first STA and the first AP operate on the first link. S104: The first STA of the non-AP MLD determines, in accordance with the individually addressed traffic indication information, whether the non-AP MLD has downlink individually addressed traffic. Specifically, the first STA of the non-AP MLD can analyze the individually addressed traffic indication information received to determine if the non-AP MLD has any downlink individually addressed traffic. If the individually addressed traffic indication information indicates that the non-AP MLD has received downlink individually addressed traffic, a station in the non-AP MLD can wake up from a sleep state, switch to an active state, and send a PS (power save poly) survey frame to an AP associated with the station to notify an AP MLD in which the AP resides that the station has been in an active state and can begin receiving downlink individually addressed traffic.After receiving the PS survey frame, the AP can respond with an acknowledgment frame and then send individually addressed downlink traffic to the STA; or it can directly send individually addressed downlink traffic to the STA after receiving the PS survey frame. If the individually addressed traffic indication information shows that the non-AP MLD has no individually addressed downlink traffic, the non-AP MLD station can continue to rest, or change from an active state to a rest state. In an 802.11 protocol, a STA typically has two operating modes: a non-power-saving mode and a power-saving mode. When operating in non-power-saving mode, the STA is in an active state (also called awake state) regardless of whether it is transmitting data. In power-saving mode, the STA may be in an active state when transmitting data with an access point (AP). When there is no data transmission between the STA and the AP, the STA may be in a doze state to reduce power consumption.The STA can send a frame to the AP to notify whether the STA is in power-saving mode. A power-saving bit of 1 in a frame control field in the MAC header of the frame is used to notify that the STA is in power-saving mode, while a power-saving bit of 0 in the frame control field of the MAC header is used to notify that the STA is in power-saving mode. Corresponding to the non-AP MLD (or the station MLD), a power-saving bit is set for each station in the non-AP MLD. It can be learned that, in this modality of this request, the individually addressed traffic indication information sent by the first AP (i.e., the reporting AP) of the AP MLD can not only indicate whether the non-AP MLD associated with the first AP MLD has downlink individually addressed traffic, but can also help the second AP MLD to indicate whether the non-AP MLD associated with the second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a broadcast AP belongs in the multiple BSSID set in which the first AP is located.This can resolve the issue where some or all APs in an AP MLD cannot indicate whether non-AP MLDs associated with the AP MLDs have individually addressed downlink traffic (note that an AP not broadcasting in the multiple BSSID set cannot transmit a beacon frame or probe response frame, resulting in a failure to send an indication of individually addressed downlink traffic), so non-AP MLDs associated with APs can normally receive individually addressed downlink traffic. This is because there is a possibility that all APs in an AP MLD are in 802.11. If APs are non-transmitting, the solution provided in this modality of this request can solve the problem that MLDs of APs whose APs are all non-transmitting cannot send individually addressed traffic indications, thereby improving the integrity and diversity of downlink individually addressed traffic indications. In an optional mode, prior to step S101 in FIGURE 6, the method may also include the following steps: S105: The first AP of the first AP MLD generates AID assignment information, where the AID assignment information carries an AID assigned to the non-AP MLD, and the AID is different from an AID of the non-AP MLD associated with the second AP MLD. S106: The first AP of the first AP MLD sends the AID assignment information. Correspondingly, the first STA of the non-AP MLD receives the AID assignment information. S107: The first STA of the non-AP MLD analyzes the received AID assignment information to learn that the AID assignment information carries the AID assigned to the non-AP MLD. The AID assignment information may be carried in an association response frame.An AID space (or a set of AIDs to be assigned) used by the first AP MLD to assign an AID to the non-AP MLD associated with the first AP MLD and an AID space (or a set of assigned AIDs) used by the second AP MLD to assign an AID to the non-AP MLD associated with the second AP MLD are the same. Optionally, the AP MLD to which the non-transmitting AP belongs in the multiple BSSID set in which the first AP is located includes one or more AP MLDs. Optionally, before step S105, the method also includes: The first STA of the non-AP MLD sends an association request frame to the first AP of the first AP MLD, where the association request frame is used to request the establishment of a multilink association with the first AP MLD. Correspondingly, the first AP of the first AP MLD receives the association request frame. Optionally, steps S105 and S106 can be performed alternatively by a second AP of the first AP MLD, and step S107 can be performed alternatively by a second STA of the non-AP MLD. Specifically, the second AP of the first AP MLD generates AID assignment information, where the AID assignment information carries the AID assigned to the non-AP MLD, and the AID is different from the AID of the non-AP MLD associated with the second AP MLD; and the second AP of the first AP MLD sends the AID assignment information. Correspondingly, the second STA of the non-AP MLD receives the AID assignment information. The second STA of the non-AP MLD analyzes the received AID assignment information to learn that the AID assignment information carries the AID assigned to the non-AP MLD. The second AP can be any AP of the first AP MLD, and the second STA can be any STA of the non-AP MLD. It can be learned that when assigning the AID, the AID of the non-AP MLD associated with the first AP MLD is different from the AID of the non-AP MLD associated with the second AP MLD, so an AID ambiguity can be avoided when individually addressing traffic from the non-AP MLD. The preceding content describes the individually addressed traffic indication method applicable to multiple links provided in this modality of this application. A specific implementation of the above individually addressed traffic indication information is described below, with reference to the individually addressed traffic indication method shown in Figure 6. (a) In a first implementation, one bit of the individually addressed traffic indication information corresponds to a non-AP MLD. The value of each bit is used to indicate whether a non-AP MLD corresponding to that bit has downlink individually addressed traffic; in other words, each bit indicates whether the non-AP MLD corresponding to that bit has downlink individually addressed traffic. The non-AP MLD here is the non-AP MLD associated with the first AP MLD and the non-AP MLD associated with the second AP MLD. (b) In a second implementation, individually addressed traffic indication information is carried in a partial virtual bitmap field of a TIM element. Figure 7 is a schematic diagram of a partial virtual bitmap field according to one modality of this application. Figure 7 shows each bit of the partial virtual bitmap field of Figure 2. For example, the partial virtual bitmap field is 251 bytes, each byte comprising eight bits. As shown in Figure 7, byte 0 comprises bits 0 to 7, byte 1 comprises bits 8 to 15, and so on, and byte 250 comprises bits 2000 to 2007.Each bit of the individually addressed traffic indication information corresponds to an AID of a non-AP MLD, and each bit of the individually addressed traffic indication information is used to indicate whether a non-AP MLD identified by an AID corresponding to that bit has downlink individually addressed traffic. The non-AP MLD in this document can be understood to be the non-AP MLD associated with the first AP MLD and the non-AP MLD associated with the second AP MLD. Because each bit of the TIM element's partial virtual bitmap field corresponds to an AID, it is necessary to assign an AID to a non-AP MLD.Furthermore, the AID space (or set of AIDs to be assigned) used by the first AP MLD to assign an AID to the non-AP MLD associated with the first AP MLD and the AID space (or set of AIDs to be assigned) used by the second AP MLD to assign an AID to the non-AP MLD associated with the second AP MLD are the same. Therefore, the AID association identifiers corresponding to bits of the individually addressed traffic indication information need to be unique; in other words, they need to be different from each other. Correspondingly, steps S101 to S104 in FIGURE 6 can be as follows: The first AP of the first AP MLD generates a TIM element, where the TIM element includes individually addressed traffic indication information; the individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic; and the second AP MLD is an AP MLD to which a non-broadcasting AP belongs in a multiple BSSID set in which the first AP is located; the first AP of the first AP MLD sends the TIM element on the first link, where the first link is the working link of the first AP; the first STA of the non-AP MLD receives the TIM element on the first link on which the first STA works;and the first STA of the non-AP MLD determines, based on the TIM element, whether the non-AP MLD has individually directed downlink traffic. The TIM element can be transported in a beacon frame, or it can be transported in another management frame, such as a TIM frame. Optionally, the beacon frame carrying the TIM element may also include a special field. For each non-AP MLD that has individually addressed downlink traffic to receive (the TIM element indicates whether there is individually addressed downlink traffic), there is a corresponding special field. This special field may be a multilink ID bitmap field or multilink ID information fields. The multilink ID bitmap field or multilink ID information fields are used to indicate one or more links for receiving individually addressed downlink traffic. One bit in the multilink ID bitmap field may correspond to one link.When a value of one or more bits is a first value such as 1, it indicates that there is individually addressed downlink traffic on one or more links corresponding to one or more bits; when a value of one or more bits is a second value such as 0, it indicates that there is no individually addressed downlink traffic on one or more links corresponding to one or more bits. Multilink identification information fields carry identifying information to distinguish different links. It can be understood that, in the TIM element, a bit is still used to indicate whether a non-AP MLD has individually addressed downlink traffic. Optionally, the special field can be a traffic identifier (TID) bitmap field, where the TID bitmap field is used to indicate that the received downlink individually addressed traffic corresponds to one or more TIDs. Then, based on the traffic identifier to link mapping negotiated between the non-AP MLD and the AP MLD, the non-AP MLD knows a station, operating on a specific link, that is used to receive notification of downlink individually addressed traffic. It can be learned that in this implementation, some bits of the beacon frame's partial virtual bitmap field are used to indicate whether a non-AP MLD associated with an MLD containing the reporting AP has downlink individually addressed traffic, and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic. Without changing the TIM element's frame format, one AP MLD can help another AP MLD indicate whether a non-AP MLD associated with a different AP MLD has downlink individually addressed traffic. This can improve the flexibility of reporting downlink individually addressed traffic. (c) Because a bit in the partial virtual bitmap field of the TIM element can indicate whether a non-AP MLD has downlink individually addressed traffic, if in the same set of co-located AP MLDs, some non-AP MLDs are associated with different AP MLDs that have the same AID, after receiving beacon frames, these non-AP MLDs cannot determine a specific STA or a specific non-AP MLD to which the downlink individually addressed traffic indications and / or link bitmap indications / TID bitmap indications carried in the beacon frames belong. For example, in FIGURE 5, if the reporting AP is AP 1x, and it is assumed that the non-AP 1 MLD is associated with AP 1x and AP 2y of the AP 1 MLD on which AP 1x is located, and the link on which AP 1x works is link 1, a non-transmitting AP on link 1 is AP 1y.When a non-AP MLD 2 is associated with AP 1y, AP 2z, and AP 4y in an AP MLD 3 in which AP 1y is located, and an AID of the non-AP MLD 1 is the same as an AID of the non-AP MLD 2, if an indication of downlink individually addressed traffic for the non-AP MLD in the TIM element sent by AP 1x is 1, it can only indicate that at least one non-AP MLD in the non-AP MLD 1 and non-AP MLD 2 has downlink individually addressed traffic, and a non-AP MLD that has downlink individually addressed traffic cannot be known. Therefore, in a third implementation, the indication for individually addressed traffic indication information is based on an AP MLD. Specifically, the second AP MLD co-located with the reporting AP corresponds to a separate TIM block, such as a partial virtual bitmap field, and the TIM block can constitute a new element. The new element can carry the individually addressed traffic indication information. The new element includes at least one TIM block corresponding to a second AP MLD (the TIM block is used to indicate whether the non-AP MLD associated with the second AP MLD has downlink individually addressed traffic). Figure 8 is a schematic diagram of a partial frame format for a new element according to one modality of this application.As shown in Figure 8, an (ID) is used, such as an MLD ID or an MLD MAC address, to indicate that the TIM block is used to show whether a specific AP MLD has individually addressed downlink traffic for a non-AP MLD associated with the AP MLD. Within each TIM block, a bit can still be used to indicate whether a non-AP MLD has individually addressed downlink traffic. Each bit in the TIM block can correspond to an AID, and therefore, an AID must be assigned to each non-AP MLD. In another implementation, a separate TIM block corresponding to the second AP MLD can alternatively be a TIM element, and the structure of the TIM element is consistent with that of the existing TIM element. In this case, the TIM element does not include an identifier for the second AP MLD. The TIM element for the second AP MLD can be located in a non-transmitted profile corresponding to a non-transmitted BSSID within a multiple BSSID element in a management frame body, where the AP corresponding to the non-transmitted BSSID belongs to the second AP MLD, and the AP corresponding to the non-transmitted BSSID and the reporting AP mentioned in the previous paragraph are in the same multiple BSSID set. Here, for the third implementation, the AIDs of all non-AP MLDs associated with the same AP MLD must be unique; in other words, they must be different from each other, thus avoiding AID ambiguity. It can be understood that, in this document, the identifiers of one or more AP MLDs in the new item submitted by the reporting AP must be unique; in other words, they must be different from each other. Alternatively, here, the identifiers of all AP MLDs in the reporting AP's co-located AP MLD set must also be unique; in other words, they must be different from each other. In other words, the AID space used by the first AP MLD to assign the AID to the non-AP MLD associated with the first AP MLD and the AID space used by the second AP MLD to assign the AID to the non-AP MLD associated with the second AP MLD are independent of each other.To be specific, an AID assigned by the first AP MLD to a non-AP MLD associated with the first AP MLD can be the same as the AID assigned by the second AP MLD to the non-AP MLD associated with the second AP MLD. For example, in Figure 5, if AP 1x is the reporting AP, AP 1's MLD is the first AP MLD. It is assumed that non-AP 1's MLD is associated with AP 1's MLD, and non-AP 2's MLD is associated with AP 3's MLD (one of the second AP MLDs). Therefore, an AID assigned by AP 1's MLD to non-AP 1's MLD can be the same as an AID assigned by AP 3's MLD to non-AP 2's MLD. It can be understood that the AID space mentioned in this request can be a set of AIDs to be assigned. Optionally, each TIM block can carry either a link bitmap indication or a TID bitmap indication. Specifically, each TIM block can include a special field, which can be a multilink identification bitmap field, multilink identification information fields, or a TID bitmap field. Optionally, the new element can be transported in a beacon frame, or it can be transported in another management frame, such as a TIM frame. It can be learned that in the TIM indication in this implementation, an ambiguity of non-AP MLD AIDs associated with different AP MLDs can be avoided by distinguishing traffic from different AP MLDs and using AP MLD IDs as TIM block indices. To indicate whether the non-AP MLD associated with the first AP (i.e., the reporting AP) has individually addressed downlink traffic, and whether the non-AP MLD associated with the second AP MLD has individually addressed downlink traffic, the first AP of the first AP MLD also needs to assign an AID to each non-AP MLD before generating the individually addressed traffic indication information. Mode 2 Modality 2 of this application describes a method for assigning an AID to a multilink device, and the method is specifically a method for assigning an AID to a non-AP MLD. The AID can be understood as an identifier (ID) assigned by an AP to an associated STA after the association is established, and can be considered as an ID of the associated STA. The AID can be used to identify and distinguish the STAs associated with the AP, and can be used as an index in a partial frame structure to point to a specific associated STA. If the AP can support multiple BSSIDs, or if a beacon frame or probe response frame can carry a multiple BSSID element, the maximum number of BSSIDs the AP can support is 2^n, indicating that the range of a number of BSSIDs is [1, 2^n - 1], and the range of an AID the AP can assign to the STA is [2^n, 2007]. Here, n can be a value of a MaxBSSID indicator field in the BSSID element.If the AP cannot support multiple BSSIDs, or the beacon frame or probe response frame cannot carry the multiple BSSID element, the range of AIDs that the AP can assign to the STA is [1,2007]. In a small area, there may be multiple types of users or users supporting multiple types of services. If different access points (APs) are used in this small area, channel interference between different APs is inevitable because each AP attempts to find a channel with little or no interference. To address this, IEEE 802.11ax provides a way to create multiple APs using a single physical AP, through virtualization, to handle different types of traffic or serve different types of clients. Therefore, a virtual AP can have one BSSID, while a physical AP can have multiple BSSIDs. In other words, a single AP can support multiple BSSIDs. It can also be understood that multiple STAs included in a non-AP MLD can share the same AID; in other words, a non-AP MLD has only one AID. It can be understood that, in practical applications, Mode 2 of this request can be implemented separately, or it can be implemented in combination with Mode 1. This is not limited in this application. Specifically, Mode 2 of this request can be implemented in combination with the second implementation of individually addressed traffic indication information in Mode 1. It can be understood that, similar to the co-located AP MLD set of the AP in the previous report, a co-located AP MLD set of any AP (for ease of description, AP1 is used as an example) includes the following APs: (1) all APs that belong to the same AP MLD as AP¡, or all APs in the AP MLD in which AP¡ is located; (2) all APs in an AP MLD in which a non-broadcasting AP is in the same multiple BSSID set as AP1; or all APs in an AP MLD in which a non-broadcasting AP is in a multiple BSSID set as AP1; and (3) all APs in an AP MLD that meets the following two conditions: 1) at least one AP in the AP MLD is in the same multiple BSSID as an AP in the AP MLD in which AP1 is located; and 2) there is no AP in the AP MLD working on the same link as AP1. Figure 9 is a schematic flowchart of a method for assigning an AID to a non-AP MLD based on a specific request modality. As shown in Figure 9, the method for assigning an AID includes, but is not limited to, the following steps: S201: An AP of an AP MLD generates AID allocation information, wherein the AID allocation information carries an AID allocated to the non-AP MLD, the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a collocated AP MLD set of AP, or the target AP MLD is any AP MLD in a group of sets in which the collocated AP MLD set of AP is located. S202: The AP MLD AP sends the AID assignment information to a non-AP MLD STA. Consequently, the non-AP MLD STA receives the AID assignment information. The AP MLD in this application modality can be a first AP MLD or a second AP MLD in modality 1 or another AP MLD. The AP is any AP of the AP MLD. Implementation A: The target AP MLD is any AP MLD in the AP co-located AP MLD set. In the colocated AP MLD set of AP1 mentioned in this modality of this application, all AP MLDs (APs included in the AP MLDs) are colocated with AP1. Both the AP MLD and the target AP MLD belong to the colocated AP MLD set of AP1. Specifically, the AID allocation information can carry the AID assigned to the non-AP MLD. This AID is different from the AID of the non-AP MLD associated with the target AP MLD, and the target AP MLD is any AP MLD in the AP's collocated AP MLD set. In other words, an AID space or a set of AIDs to be allocated used by the AP MLD to allocate an AID to the non-AP MLD associated with the AP MLD, and an AID space or a set of AIDs to be allocated used by the target AP MLD to allocate an AID to the non-AP MLD associated with the target AP MLD, are the same. It can be understood that the AID assigned to the non-AP MLD is also different from an AID of a non-AP MLD associated with the AP MLD. Optionally, the non-AP MLD associated with the AP MLD in this form of this request may be understood in the following two ways: 1) all non-AP MLDs that establish multilink associations with the AP MLD, where the non-AP MLD may establish associations with some or all of the APs in the AP MLD; and 2) a non-AP MLD associated with AP1 of the AP MLD, where the non-AP MLD may establish associations with some or all of the APs in the AP MLD, provided that some or all of the APs need to include AP1. In this document, AP1 is an AP in the AP MLD that is assigned an AID. Figure 10a is a schematic diagram of a set of MLDs of APs colocated with an AP according to a modality of this request. As shown in Figure 10a, AP1 is assumed to be AP 1x. Then, a set of APs colocated with AP 1x includes: AP 2y, AP 1y, AP 2x, AP 3y, and AP 4y. Therefore, the co-located AP MLD set of AP 1x includes: the AP 1 MLD and the AP 3 MLD. Therefore, the AID carried in the AID assignment information and assigned to the non-AP MLD is different from the AID of the non-AP MLD associated with the AP 1 MLD, and is also different from an AID of a non-AP MLD associated with the AP 3 MLD. In other words, the AID of the non-AP MLD associated with the AP 1 MLD and the AID of the non-AP MLD associated with the AP 3 MLD must be unique; in other words, they must be different from each other. Figure 10b is another schematic diagram of a set of MLDs of APs colocated with an AP according to a modality of the present application. As shown in Figure 10b, AP1 is assumed to be AP 1x. Then, a set of APs colocated with AP 1x includes: AP 2y, AP 3x, AP 1y, AP 2z, AP 4y, AP 2x, and AP 4x. Therefore, the co-located AP MLD set of AP 1x includes: AP 1 MLD, AP 2 MLD, and AP 3 MLD. Therefore, the AID carried in the AID assignment information and assigned to the non-AP MLD is different from the AID of the non-AP MLD associated with AP 1 MLD, is also different from the AID of the non-AP MLD associated with AP 2 MLD, and is also different from an AID of a non-AP MLD associated with AP 3 MLD.In other words, the AID of the non-AP MLD associated with AP MLD 1, the AID of the non-AP MLD associated with AP MLD 2, and the AID of the non-AP MLD associated with AP MLD 3 need to be unique; in other words, they need to be different from each other. Figure 10c is another schematic diagram of a set of MLDs of APs colocated with an AP according to a modality of the present application. As shown in Figure 10c, AP1 is assumed to be AP 3x. Then, a set of APs colocated with AP 3x includes: AP 1x, AP 2y, AP 2x, AP 4x, AP 1y, and AP 2z. Therefore, the co-located AP MLD set of AP 3x includes: AP 1 MLD, AP 2 MLD, and AP 3 MLD. Therefore, the AID carried in the AID assignment information and assigned to the non-AP MLD is different from the AID of the non-AP MLD associated with AP 1 MLD, is also different from the AID of the non-AP MLD associated with AP 2 MLD, and is also different from an AID of a non-AP MLD associated with AP 3 MLD.In other words, the AID of the non-AP MLD associated with AP MLD 1, the AID of the non-AP MLD associated with AP MLD 2, and the AID of the non-AP MLD associated with AP MLD 3 need to be unique; in other words, they need to be different from each other. Figure 5 is still used as an example. AP1 is assumed to be AP4x. Then, a set of APs co-located with AP 4x includes: AP 2x, AP 4y, AP 2z, AP 1y, AP 4z, AP 5, AP 1x, AP 2y, and AP 3. Therefore, the set of AP MLDs co-located with AP 4x includes: the MLD of AP 1, the MLD of AP 2, the MLD of AP 3, and an MLD of AP 4. Therefore, the AID carried in the AID assignment information and assigned to the non-AP MLD is different from the AID of the non-AP MLD associated with the MLD of AP 1, is also different from the AID of the non-AP MLD associated with the MLD of AP 2, is also different from the AID of the non-AP MLD associated with the MLD of AP 3, and is also different from the AID of a non-AP MLD associated with the MLD of AP 4.In other words, the AID of the non-AP MLD associated with AP MLD 1, the AID of the non-AP MLD associated with AP MLD 2, the AID of the non-AP MLD associated with AP MLD 3, and the AID of the non-AP MLD associated with AP MLD 4 must be unique; in other words, it must be different from each other. Implementation B: The target AP MLD is any AP MLD in an established group in which the co-located AP MLD is located. In the group of sets in which the colocated AP MLD set of AP1 mentioned in this modality of this application is located, some AP MLDs are colocated with AP1, and some other AP MLDs are colocated with other APs outside the AP1 colocated AP MLD set. In other words, the AP1 colocated AP MLD set and a set of AP MLDs colocated from an AP other than AP1 within the AP1 colocated AP MLD set constitute the group of sets. In this document, both the AP MLD and the target AP MLD belong to the group of sets in which the AP1 colocated AP MLD set is located. Specifically, the group of sets in which the colocated AP MLD set of AP1 is located consists of all APs in a colocated AP MLD set of any AP of an AP MLD colocated with AP1 (where any AP can be understood as AP1 again). For example, as shown in FIGURE 5, AP1 is assumed to be AP1x. Then, the colocated AP MLD set of AP 1x includes the AP 1 MLD, the AP 2 MLD, and the AP 3 MLD. Furthermore, because the colocated AP MLD set of AP 4x in the colocated AP MLD set of AP 1x includes the AP 2 MLD, the AP 3 MLD, and the AP 4 MLD, a group of sets in which the colocated AP MLD set of AP 1x lies includes the AP 1 MLD, the AP 2 MLD, the AP 3 MLD, and the AP 4 MLD.Therefore, an AID assigned by AP 1 x to the non-AP MLD, the AID of the non-AP MLD associated with the AP 1 MLD, the AID of the non-AP MLD associated with the AP 2 MLD, the AID of the non-AP MLD associated with the AP 3 MLD, and the AID of the non-AP MLD associated with the AP 4 MLD are different from each other. As shown in FIGURE 10a, AP1 is assumed to be AP 1x. Then, the colocated AP MLD set of AP 1x includes the AP 1 MLD and the AP 3 MLD. Furthermore, because a colocated AP MLD set of AP 3y in the colocated AP MLD set of AP 1x includes the AP 2 MLD and the AP 3 MLD, the group of sets in which the colocated AP MLD set of AP 1x lies includes the AP 1 MLD, the AP 2 MLD, and the AP 3 MLD. Therefore, the AID assigned by AP 1x to the non-AP MLD, the AID of the non-AP MLD associated with the AP 1 MLD, the AID of the non-AP MLD associated with the AP 2 MLD, and the AID of the non-AP MLDs associated with the AP 3 MLD are all different. As shown in FIGURE 10b, AP1 is assumed to be AP 1x. Then, the colocated AP MLD set of AP 1x includes the AP 1 MLD, the AP 2 MLD, and the AP 3 MLD, and the group of sets in which the colocated AP MLD set of AP 1x lies also includes the AP 1 MLD, the AP 2 MLD, and the AP 3 MLD. Therefore, the AID assigned by AP 1x to the non-AP MLD, the AID of the non-AP MLD associated with the AP 1 MLD, the AID of the non-AP MLD associated with the AP 2 MLD, and the AID of the non-AP MLD associated with the AP 3 MLD are all different. As shown in FIGURE 10c, AP1 is assumed to be AP 3x. Then the colocated AP MLD set of AP 3x includes the AP 1 MLD, the AP 2 MLD, and the AP 3 MLD, and the group of sets in which the colocated AP MLD set of AP 1x lies also includes the AP 1 MLD, the AP 2 MLD, and the AP 3 MLD. Therefore, the AID assigned by AP 1x to the non-AP MLD, the AID of the non-AP MLD associated with the AP 1 MLD, the AID of the non-AP MLD associated with the AP 2 MLD, and the AID of the non-AP MLD associated with the AP 3 MLD are all different. Similar to Implementation A, in Implementation B, the AID assigned to the non-AP MLD is also different from the AID of a non-AP MLD associated with the AP MLD. Optionally, for AID assignment to a single-link STA, an AID assigned by AP to the single-link STA on a current link (or a single-link STA AID associated with AP) is different from the non-AP MLD AID associated with the target AP MLD, and the target AP MLD is either any AP MLD in AP's co-located AP MLD set, or the target AP MLD is any AP MLD in the group of sets in which AP's co-located AP MLD set is located. For example, as shown in FIGURE 10a, AP1 is assumed to be AP1x, and AP1x is on link 1. Therefore, the AID of a single-link STA on link 1 is different from the AID of the non-AP MLD associated with the MLD of AP1, and it is also different from the AID of the non-AP MLD associated with the MLD of AP3. In other words, the AID of the single-link STA on link 1, the AID of the non-AP MLD associated with the MLD of AP1, and the AID of the non-AP MLD associated with the MLD of AP3 must be unique; that is, they must be different from each other. It can be further understood that, in addition to the AID of the associated single-link STA on link 1, an AID of an associated single-link STA on link 2 can be the same as an AID of a non-AP MLD associated with the target AP MLD. Alternatively, as shown in FIGURE 10a, AP1 is assumed to be AP1x and AP1x is on link 1. Then, an AID of a single-link STA on link 1 is different from each of the AID of the non-AP MLD associated with the MLD of AP1, the AID of the non-AP MLD associated with the MLD of AP2, and the AID of the non-AP MLD associated with the MLD of AP3. It can be understood that, in a wireless communication system, the identifier of an AP MLD is 0 by default, and several APs within the AP MLD share the identifier (i.e., identifier 0). However, the multiple APs within the AP MLD can, alternatively, have different identifiers. It can also be understood that cross-link TIM indication can be performed under the same AP MLD. Specifically, if AP 1 and AP 2 belong to the same AP MLD, AP 1 can add AP 2's TIM information to a TIM indication to show whether AP 2 has traffic for the non-AP MLD associated with it. Therefore, the AIDs of multiple non-AP MLDs associated with the same AP MLD are different from each other. Therefore, if the same identifier system is used, such as the range [1,2007], the identifiers of multiple APs within the AP MLD must be unique; in other words, they must be different from each other. The AIDs of multiple non-AP MLDs associated with the same AP MLD must also be unique; in other words, they must be different from each other. In this application, an AID assigned to a non-AP MLD is a value selected from the remaining space and also needs to be unique. The remaining space here refers to a set of values ​​remaining in the range [1,2007], other than the values ​​that have been used and are not allowed to be reused. Optionally, AID assignment information can be carried in an association response frame, or it can be carried in other frames. Specifically, an AID assigned to the non-AP MLD in the AID assignment information can be carried in an AID element of the association response frame. Figure 11 is a schematic diagram of an AID element frame format according to one modality of this request. As shown in Figure 11, the AID element includes a 1-byte element identifier field, a 1-byte length field, and a 2-byte AID field. Optionally, the association response frame can also carry information such as a link identifier for each AP. The association response frame is used to confirm that a multi-link association has been established with the non-AP MLD. S203: The non-AP MLD STA analyzes the received association response frame to obtain an AID carried in the association response frame. Optionally, before step S201, the method also includes the following steps: S204: The non-AP MLD STA generates an association request frame. S205: The non-AP MLD STA sends the association request frame to the AP MLD's AP1, where the association request frame is used to request the establishment of a multi-link association with the AP MLD. Consequently, the AP MLD's AP1 receives the association request frame. The association request frame can carry a link identifier for each non-AP MLD STA and information about each STA. Optionally, after receiving the association request frame, the AP MLD's AP can send an acknowledgment frame to the non-AP MLD's STA, where the acknowledgment frame is used to acknowledge that the AP MLD's AP has received the association request frame. In this version of the request, when assigning an AID to a non-AP MLD, the solution described in version 1 is considered: An AP MLD helps another AP MLD indicate whether a non-AP MLD associated with another AP MLD has individually addressed downlink traffic. Therefore, the AID is not the AID of the non-AP MLD associated with the target AP MLD. The target AP MLD is either any AP MLD in the APi co-located set of AP MLDs, or any AP MLD in the group of sets in which the APi co-located set of AP MLDs is located, thus avoiding AID ambiguity when indicating whether the non-AP MLD has individually addressed downlink traffic. Mode 3 In mode 3 of this application, the problem of some APs in an AP MLD being unable to indicate whether a non-AP MLD associated with the AP MLD has downlink individually addressed traffic is resolved by limiting the link on which the non-AP MLD listens for an indication of downlink individually addressed traffic. Furthermore, in this case, an AP in another AP MLD operating on the same link as the aforementioned some APs does not assist the aforementioned some APs in sending downlink individually addressed traffic indications. For example, in Figure 5, if AP 1x is the reporting AP, it is assumed that non-AP MLD 1 is associated with AP 2y and AP 3 of AP MLD 1.If the MLD of non-AP 1 listens only on link 2 for an indication of downlink individually addressed traffic, AP 2y (an AP not broadcast in a multiple BSSID set) of AP 1's MLD cannot send an indication of downlink individually addressed traffic. Furthermore, an AP broadcast in the same multiple BSSID set on the same link does not help send an indication of downlink individually addressed traffic from the MLD containing AP 2y. In this case, the MLD of non-AP 1 listening on link 2 cannot receive an indication of downlink individually addressed traffic; in other words, the MLD of non-AP 1 cannot determine if the MLD of non-AP 1 has downlink individually addressed traffic. Therefore, modality 3 of this request provides a method for individually directed traffic indication applicable to multiple links. Figure 12 is another schematic flowchart of an individually directed traffic indication method applicable to multiple links under modality 3 of this request. As shown in Figure 12, the method includes the following steps. S1: An AP reporting AP of an AP MLD generates a management frame, such as a beacon frame, where the beacon frame carries a TIM element, and a partial virtual bitmap field of the TIM element is used to indicate whether a non-AP MLD associated with the AP MLD has individually addressed downlink traffic. S2: The AP reporting MLD sends the management frame, like the beacon frame, on a working link of the reporting AP. For a TIM element-specific frame format, see FIGURE 2. For a frame format of a partial virtual bitmap field, see FIGURE 7. The details are not described again here. S3: A non-AP MLD STA listens for the management frame, such as the beacon frame, on one or more links, where the one or more links include a first link, and the first link is a link on which a transmitting AP, in a set of multiple BSSIDs, from an AP MLD associated with the non-AP MLD works or an AP that does not belong to the set of multiple BSSIDs works. S4: The non-AP MLD STA analyzes the management frame, such as the beacon frame obtained by listening on a link where the reporting AP is working, to determine if the non-AP MLD has individually addressed downlink traffic. Specifically, for step S3, in other words, the non-AP MLD STA cannot listen to the beacon frame only on a link where there is a non-broadcasting AP in the multiple BSSID set. The non-AP MLD STA can listen to the beacon frame or another management frame on a link where there is a broadcasting AP included in the multiple BSSID set or an AP that is not part of the multiple BSSID set. For example, in FIGURE 5, if AP 1x is the reporting AP, the non-AP 1 MLD is assumed to be associated with AP 1x, AP 2y, and AP 3 of the AP 1 MLD. If AP 1x sends a beacon frame on link 1, the non-AP 1 MLD listens for a beacon frame on link 1, or on link 1 and link 2, or on link 1 and link 3, or on link 3. The non-AP 1 MLD cannot listen for a beacon frame on link 2 alone. Optionally, the links on which a non-AP MLD listens cannot include only one link on which a non-transmitting AP of an associated AP MLD operates. For example, as shown in FIGURE 5, the links on which the non-AP MLD listens can include link 1 and link 2, or link 1 and link 3, or link 2 and link 3, or link 1, link 2, and link 3; but not just link 2. It can be learned that in this application mode, a link on which the non-AP MLD listens for an indication of downlink individually addressed traffic is limited, so that the non-AP MLD listens on a link (referred to as the first link for ease of description) on which an AP is operating, transmitted from a set of multiple BSSIDs, from an AP MLD associated with the non-AP MLD, or an AP that does not belong to the set of multiple BSSIDs is operating. Furthermore, because the AP transmitted from the AP MLD and the AP that does not belong to the set of multiple BSSIDs can send a beacon frame (the beacon frame carries an indication of downlink individually addressed traffic), the non-AP MLD can obtain a beacon frame by listening on the first link, so that it can be determined, by analyzing the beacon frame, whether the non-AP MLD has downlink individually addressed traffic. The preceding content describes in detail the methods provided in this application. To better implement the above solutions in the modalities of this application, the modalities of this application also provide the corresponding apparatus or devices. In the modalities of this application, the multilink device can be divided into functional modules based on the examples of the methods described above. For example, each functional module can be obtained by dividing it into its corresponding functions, or two or more functions can be integrated into a single processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that, in the modalities of this application, module division is an example and simply a logical functional division. In actual implementation, a different form of division may be used. Communication devices in the modalities of this application are described in detail below with reference to Figures 11 through 17. The communication device is an access point in an access point multilink device or a station in a station multilink device.In addition, the communications device can be a device in an AP MLD, or a device in a STA MLD. When an integrated unit is used, FIGURE 13 is a schematic diagram of a communications apparatus 1 structure according to one modality of this application. As shown in FIGURE 13, the communications apparatus 1 includes a processing unit 11 and a transceiver unit 12. Communications Device 1 can be a first AP MLD or a chip in the first AP MLD, for example, a Wi-Fi chip, or it can be a first AP of the first AP MLD. The first AP is a reporting AP and belongs to the first AP MLD. In one design, processing unit 11 is configured to generate individually addressed traffic indication information. Transceiver unit 12 is configured to send the individually addressed traffic indication information on a first link, where the first link is a working link of the first AP. The individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs in a multiple BSSID set in which the first AP is located. It can be learned that in communications apparatus 1, the individually addressed traffic indication information generated by processing unit 11 can not only indicate whether the non-AP MLD associated with the first AP MLD has downlink individually addressed traffic, but also help the second AP MLD indicate whether the non-AP MLD associated with the second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs in a multiple BSSID set in which the first AP is located. This can resolve the problem that some or all APs in the AP MLDs cannot indicate whether the non-AP MLDs associated with the AP MLDs have downlink individually addressed traffic, so that the non-AP MLDs associated with the APs can normally receive downlink individually addressed traffic. Optionally, processing unit 11 is further configured to generate AID assignment information, where the AID assignment information carries an AID assigned to the non-AP MLD, and the AID is different from the AID of the non-AP MLD associated with the second AP MLD; and transceiver unit 12 is further configured to send the AID assignment information. The AID assignment information is carried in an association response frame. It can be understood that the AID assignment information may alternatively be carried in other frames. Optionally, transceiver unit 12 is further configured to receive an association request frame, where the association request frame is used to request the establishment of a multilink association with communications apparatus 1. It should be understood that the communications apparatus 1 in this design can correspondingly perform mode 1, and the above operations or functions of each unit in communications apparatus 1 are used separately to implement the corresponding operations of the first AP of the first AP MLD in mode 1. For brevity, the details are not described again here. Optionally, communications appliance 1 can be an AP MLD or a chip in the AP MLD, for example, a Wi-Fi chip, or it can be an AP reporting AP of the AP MLD. In another design, processing unit 11 is configured to generate a management frame as a beacon frame, where the beacon frame carries a TIM element, and a partial virtual bitmap field of the TIM element is used to indicate whether a non-AP MLD associated with the AP MLD has individually addressed downlink traffic. Transceiver unit 12 is configured to send the management frame, as the beacon frame, on a working link of transceiver unit 12. It should be understood that the communications apparatus 1 in this design can correspondingly perform mode 3, and the above operations or functions of each unit in communications apparatus 1 are used separately to implement corresponding AP operations of the AP MLD reporting in mode 3. For brevity, the details are not described again here. Figure 14 is a schematic diagram of a communications apparatus 2 structure according to one modality of this application. As shown in Figure 14, the communications apparatus 2 includes a transceiver unit 21 and a processing unit 22. Communications Appliance 2 can be a non-AP MLD or a chip in the non-AP MLD AP, for example, a Wi-Fi chip, or it can be a first STA in the non-AP MLD. In one design, the transceiver unit 21 is configured to receive individually addressed traffic indication information on a first link on which the communications apparatus 2 operates. The processing unit 22 is configured to determine, based on the received individually addressed traffic indication information, whether the non-AP MLD on which the communications apparatus 2 is located has downlink individually addressed traffic. The individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with a first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs in a multiple BSSID set on which the first AP is located. It can be learned that in communications apparatus 2, processing unit 22 can learn, according to the individually addressed traffic indication information, if processing unit 22 has downlink individually addressed traffic, to ensure that processing unit 22 can receive downlink individually addressed traffic. Optionally, transceiver unit 21 can be further configured to receive AID assignment information. Processing unit 22 can also be configured to analyze the received AID assignment information to learn that the AID assignment information carries an AID assigned to the non-AP MLD. This AID is different from the AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a set of AP MLDs co-located from the first AP. The AID assignment information is carried in an association response frame. It can be understood that the AID assignment information may alternatively be carried in other frames. Optionally, processing unit 22 is also configured to generate an association request frame. Transceiver unit 21 is further configured to send the association request frame to a second AP of the first AP MLD. The association request frame is used to request the establishment of a multilink association with the first AP MLD. It should be understood that the communications apparatus 2 in this design can correspondingly perform mode 1, and the above operations or functions of each unit in communications apparatus 2 are used separately to implement the corresponding operations of the first STA of the non-AP MLD in mode 1. For brevity, the details are not described again here. Optionally, the communications appliance 2 can be a non-AP MLD or a chip in the non-AP MLD, for example, a Wi-Fi chip, or it can be any STA in the non-AP MLD. In another design, transceiver unit 21 is configured to listen for a management frame, such as a beacon frame, on one or more links. The one or more links include a first link, and the first link is a link on which an AP transmits, in a set of multiple BSSIDs, from an AP MLD associated with the non-AP MLD it works with, or from an AP that does not belong to the set of multiple BSSIDs it works with. Processing unit 22 is configured to analyze the management frame, such as the beacon frame, obtained by listening on a link on which a reporting AP works, to determine whether the non-AP MLD has individually addressed downlink traffic. It should be understood that the communications apparatus 2 in this design can correspondingly perform mode 3, and the above operations or functions of each unit in communications apparatus 2 are used separately to implement the corresponding operations of the non-AP MLD STA in mode 3. For brevity, the details are not described again here. Figure 15 is a schematic diagram of a communication device 3 structure according to one modality of this application. The communication device 3 may be an AP MLD or a chip within the AP MLD, for example, a Wi-Fi chip. Optionally, the communication device 3 corresponds to the AP MLD described in modality 2 or any AP within the AP MLD. As shown in Figure 15, the communication device 3 includes a processing unit 31 and a transceiver unit 32. Processing unit 31 is configured to generate AID assignment information, where the AID assignment information carries an AID assigned to a non-AP MLD, the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a co-located AP MLD set of an APi, or the target AP MLD is any AP MLD in a group of sets in which the co-located AP MLD set of the APi is located. Transceiver unit 32 is configured to send the AID assignment information. The APi is any AP of an AP MLD. Optionally, if the target AP MLD is any AP MLD in a co-located AP MLD set of the APi, then both the AP MLD and the target AP MLD belong to the co-located AP MLD set of the APi. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, the transceiver unit 32 is further configured to receive an association request frame, where the association request frame is used to request the establishment of a multilink association with the AP MLD. It can be learned that in communications apparatus 3, the AID assigned to the non-AP MLD and carried in the AID assignment information generated by processing unit 31 is different from the AID of a non-AP MLD associated with a target deAP MLD. The target deAP MLD in this document is any deAP MLD in the APi's co-located AP MLD set, or the target AP MLD is any AP MLD in a group of co-located deAP MLD sets from the APi. This avoids AID ambiguity when indicating whether the non-AP MLD has individually addressed downlink traffic. It should be understood that the communications apparatus 3 described in this modality of this application can correspondingly perform modality 2, and the above operations or functions of each unit in the communications apparatus 3 are used separately to implement the corresponding operations of the MLD deAP API in modality 2. For brevity, the details are not described again here. Figure 16 is a schematic diagram of a communication device 4 structure according to one modality of this application. The communication device 4 may be a non-AP MLD or a chip within the non-AP MLD, for example, a Wi-Fi chip. Optionally, the communication device 4 corresponds to the non-AP MLD described in modality 2 or any STA of the non-AP MLD. As shown in Figure 16, the communication device 4 includes a transceiver unit 41 and a processing unit 42. Transceiver unit 41 is configured to receive AID assignment information from an access point (AP) MLD. Processing unit 42 is configured to analyze the received AID assignment information to obtain an AID that is assigned to a non-AP MLD and carried in the AID assignment information, where the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a co-located AP MLD set of an APi, or the target AP MLD is any AP MLD in a group of sets in which the co-located AP MLD set of the APi is located. The APi is any AP in an AP MLD. Optionally, if the target AP MLD is any AP MLD in a co-located AP MLD set of the APi, then both the AP MLD and the target AP MLD belong to the co-located AP MLD set of the APi. Optionally, AID assignment information is carried in an association response frame. It can be understood that AID assignment information may alternatively be carried in other frames. Optionally, processing unit 42 is also configured to generate an association request frame. Transceiver unit 41 is further configured to send the association request frame, which is used to request the establishment of a multilink association with the AP's MLD. It should be understood that the communications apparatus 4 described in this modality of this application can correspondingly perform modality 2, and the above operations or functions of each unit in communications apparatus 4 are used separately to implement corresponding non-AP MLD STA operations in modality 2. For brevity, the details are not described again here. The foregoing describes the AP MLD and the non-AP MLD in the forms covered by this application. The possible product forms of the AP MLD and the non-AP MLD are described below. It should be understood that any product in any form that has functions of the AP MLD in FIGURE 13 or FIGURE 15 and any product in any form that has functions of the non-AP MLD in FIGURE 14 or FIGURE 16 falls within the scope of protection of the forms covered by this application. It should further be understood that the following descriptions are merely examples, and the product forms of the AP MLD and the non-AP MLD in the forms covered by this application are not limited to them. In a possible product form, the AP MLD and the non-AP MLD in the modalities of this application can be implemented using a general bus architecture. Figure 17 is a schematic diagram of a communication apparatus 1000 structure according to one embodiment of this application. The communication apparatus 1000 may be an AP MLD, a non-AP MLD, or an apparatus within the AP MLD or the non-AP MLD. As shown in Figure 17, the communication apparatus 1000 includes a processor 1001 and a transceiver 1002 that is internally connected to and communicates with the processor. The processor 1001 is a general-purpose processor, a dedicated processor, or the like. For example, the processor 1001 may be a baseband processor or a central processing unit.The baseband processor can be configured to process a communications protocol and communications data, and the central processing unit can be configured to control a communications device (e.g., a base station, a baseband chip, a terminal, a terminal chip, a DU, or a CU) to execute a computer program or to process data from the computer program. The 1002 transceiver may be referred to as a transceiver unit, transceiver, transceiver circuit, or similarly, and is configured to implement a transceive function. The 1002 transceiver may include a receiver and a transmitter. The receiver may be referred to as a receiving machine, receiving circuit, or similarly, and is configured to implement a receiving function. The transmitter may be referred to as a transmitting machine, transmitting circuit, or similarly, and is configured to implement a transmitting function.Optionally, the communications apparatus 1000 may also include an antenna 1003. Optionally, the communications device 1000 may include one or more memories 1004. The memory 1004 may store instructions. The instructions may be a computer program. The computer program may be executed on the communications device 1000, enabling the communications device 1000 to perform the methods described in the preceding method modalities. Optionally, the memory 1004 may also store data. The communications device 1000 and the memory 1004 may be arranged separately or integrated together. The processor 1001, the transceiver 1002, and the memory 1004 can be connected via a communications bus. In one design, the communications device 1000 can be configured to perform the functions of the first AP of the first AP MLD in Mode 1 above. The processor 1001 can be configured to perform step S101 in Figure 6 and / or another process of the technology described herein. The transceiver 1002 can be configured to perform step S102 in Figure 6 and / or another process of the technology described herein. In one design, the communications device 1000 can be configured to perform the functions of the first non-AP MLD STA in Mode 1 above. The processor 1001 can be configured to perform step S104 in Figure 6 and / or another process of the technology described herein. The transceiver 1002 can be configured to perform step S103 in Figure 6 and / or another process of the technology described herein. In one design, the communications device 1000 can be configured to perform AP functions in the AP MLD in Mode 2 above. The processor 1001 can be configured to perform step S201 in Figure 9 and / or another process of the technology described herein. The transceiver 1002 can be configured to perform step S202 in Figure 9 and / or another process of the technology described herein. In one design, the communications unit 1000 can be configured to perform non-AP MLD STA functions in Mode 2 above. The processor 1001 can be configured to perform steps S203 and S204 in Figure 9 and / or another process of the technology described herein. The transceiver 1002 can be configured to perform step S205 in Figure 9 and / or another process of the technology described herein. In one design, the communications device 1000 can be configured to perform AP reporting functions for the AP MLD in Mode 3 above. The processor 1001 can be configured to perform step S1 in Figure 12 and / or another process of the technology described herein. The transceiver 1002 can be configured to perform step S2 in Figure 12 and / or another process of the technology described herein. In one design, the communications unit 1000 can be configured to perform yc / Rzn / eznz / a / YiAi functions of the non-AP MLD STA in mode 3 above. The processor 1001 can be configured to perform step S4 in FIGURE 12 and / or another process of the technology described herein. The transceiver 1002 can be configured to perform step S3 in FIGURE 12 and / or another process of the technology described herein. In any of the above designs, the 1001 processor can include a transceiver configured to perform receive and transmit functions. For example, the transceiver can be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit configured to perform receive and transmit functions can be separate or integrated. The transceiver circuit, interface, or interface circuit can be configured to read and write code / data. Alternatively, the transceiver circuit, interface, or interface circuit can be configured to transmit or transfer a signal. In any of the preceding designs, processor 1001 can store instructions. The instructions can be a computer program. The computer program runs on processor 1001, enabling communications device 1000 to perform the methods described in the previous method modalities. The computer program can be fixed within processor 1001. In this case, processor 1001 can be implemented in hardware. In one implementation, the 1000 communications apparatus may include a circuit, and the circuit may implement a transmit, receive, or communicate function in the modes of the preceding method. The processor and transceiver described in this application may be implemented on an integrated circuit (IC), an analog IC, a radio frequency integrated circuit (RFIC), a mixed-signal IC, an application-specific integrated circuit (ASIC), a printed circuit board (PCB), an electronic device, or the like.The processor and transceiver can be fabricated using various Cl technologies, for example, a complementary metal oxide semiconductor (CMOS), an N-type metal oxide semiconductor (n-Metal-oxide-semiconductor, NMOS), a positive channel metal oxide semiconductor (PMOS), a bipolar junction transistor (BJT), a bipolar CMOS (BiCMOS), silicon germanium (SiGe), and gallium arsenide (GaAs). The scope of the communications apparatus described in this application is not limited to it, and the structure of the communications apparatus may not be limited by FIGURE 17. The communications apparatus may be a standalone device or it may be part of a larger device. For example, the communications apparatus may be: (1) a stand-alone integrated circuit IC, a chip or a chip system or subsystem; (2) an assembly that includes one or more ICs (integrated circuits), where optionally, the IC assembly may further include a storage component configured to store data and a computer program; (3) an ASIC, for example, a modem (Modem); (4) a module that can be integrated into another device; (5) a receiver, a terminal, a smart terminal, a cell phone, a wireless device, a portable device, a mobile unit, a vehicle-mounted device, a network device, a cloud device, an artificial intelligence device or the like; or (6) another device or the like. In a possible product form, the AP MLD and the non-AP MLD in modalities of this application can be implemented by means of a general-purpose processor. A general-purpose processor implementing the AP MLD includes a processing circuit and an input / output interface that is internally connected to and communicates with the processing circuit. In one design, the general-purpose processor can be configured to perform functions of the first AP of the first AP MLD in Mode 1 above. Specifically, the processing circuit is configured to perform step S101 in Figure 6 and / or another process of the technology described herein. The input / output interface is configured to perform step S102 in Figure 6 and / or another process of the technology described herein. In another design, the general-purpose processor can be configured to perform AP functions in the AP MLD of Mode 2 described above. Specifically, the processing circuitry is configured to perform step S201 in Figure 9 and / or another process of the technology described herein. The input / output interface is configured to perform step S202 in Figure 9 and / or another process of the technology described herein. In another design, the general-purpose processor can be configured to perform AP reporting functions in the AP MLD mode 3 described above. Specifically, the processing circuitry is configured to perform step S1 in Figure 12 and / or another process of the technology described herein. The input / output interface is configured to perform step S2 in Figure 12 and / or another process of the technology described herein. A general-purpose processor implementing the non-AP MLD includes a processing circuit and an input / output interface that is internally connected to and communicates with the processing circuit. In one design, the general-purpose processor can be configured to perform functions of the first STA of the non-AP MLD in Mode 1 above. Specifically, the processing circuit is configured to perform the step S104 in FIGURE 6 and / or another process of the technology described in this description. The input / output interface is configured to perform step S103 in FIGURE 6 and / or another process of the technology described in this description. In another design, the general-purpose processor can be configured to perform functions of the noAP MLD STAdel in Mode 2 above. Specifically, the processing circuit is configured to perform steps S203 and S204 in Figure 9 and / or another process of the technology described herein. The input / output interface is configured to perform step S205 in Figure 9 and / or another process of the technology described herein. In another design, the general-purpose processor can be configured to perform functions of the noAP MLD STAdel in mode 3 above. Specifically, the processing circuit is configured to perform step S4 in FIGURE 12 and / or another process of the technology described herein. The input / output interface is configured to perform step S3 in FIGURE 12 and / or another process of the technology described herein. In a possible product form, the AP MLD and the nonAP MLD in the modalities of this application may be alternatively implemented using the following: one or more FPGAs (field-programmable gate arrays), a PLD (programmable logic device), a controller, a state machine, gate logic, a discrete hardware component, any other suitable circuit, or any combination of circuits that can perform various functions described in this application. It should be understood that the communication devices in the various forms of the above products have any function of the AP MLD or the non-AP MLD in the modes of the above methods. The details are not described again here. One form of this request also provides a computer-readable storage medium. The computer-readable storage medium stores computer program code. When the processor executes the computer program code, an electronic device performs the method in one of the above forms. One form of this request also provides a computer program product. When the computer program product is run on a computer, the computer is enabled to perform the method in any of the above forms. One modality of this application further provides a communications device. The device may exist in the form of a chip product. One device structure includes a processor and an interface circuit. The processor is configured to communicate with another device using a receiver circuit, to enable the device to perform the method in any of the above modalities. One version of this application further provides a wireless communications system, which includes an AP MLD and a non-AP MLD. The AP MLD and the non-AP MLD can implement the method in any of the above modes. The steps of the method or algorithm described in combination with the content disclosed in this application may be implemented using hardware, or they may be implemented using a processor by executing software instructions. The software instructions may include a corresponding software module. The software module may be stored in random access memory (RAM), flash memory, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), a register, a hard disk, a removable hard disk, a compact disc (CD-ROM), or any other form of storage medium known in the art.For example, a storage medium is coupled to a processor, so the processor can read information from the storage medium or write information to the storage medium. The storage medium can certainly be a component of the processor. The processor and the storage medium can be arranged in an ASIC. Furthermore, the ASIC can be located in a core network interface device. The processor and the storage medium can also exist as discrete components within the core network interface device. A person skilled in the art should be aware that in one or more of the preceding examples, the functions described in this application may be implemented by hardware, software, firmware, or any combination thereof. When the functions are implemented by software, they may be stored on a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. A computer-readable medium includes a computer-readable storage medium and a communication medium. A communication medium includes any means that facilitates the transmission of a computer program from one location to another. A storage medium may be any available medium accessible to a general-purpose or special-purpose computer. In the specific implementations above, the objectives, technical solutions, and beneficial effects of this application are described in more detail. It should be understood that the above descriptions are merely specific implementations of this application and are not intended to limit its scope of protection. Any modification, equivalent replacement, improvement, or similar action based on the technical solutions in this application will be included within its scope of protection.

Claims

1. A method of individually addressed traffic indication applicable to multiple links, characterized in that it comprises: generating, by means of a first access point (AP) of a first access point multilink device (AP MLD), individually addressed traffic indication information, wherein the individually addressed traffic indication information is used to indicate whether a first non-access point multilink device (non-AP MLD) associated with the first AP MLD has downlink individually addressed traffic and whether a second non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs, and the non-transmitting AP is in a set of multiple basic service set identifiers (BSSIDs) in which the first AP is located;and send, through the first AP of the first AP MLD, the individually addressed traffic indication information.; 2. A method of individually addressed traffic indication applicable to multiple links, characterized in that it comprises: receiving, by means of a first station (STA) of a non-AP multi-link device (non-AP MLD), individually addressed traffic indication information, and the non-AP MLD is a first non-AP MLD associated with a first AP MLD or a second non-AP MLD associated with a second AP MLD; and wherein the individually addressed traffic indication information is used to indicate whether the first non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether the non-AP MLD associated with the second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs, and the non-transmitting AP is in a multiple BSSID set in which a first AP of the first AP MLD is located;and determine, by means of the first STA of the non-AP MLD in accordance with the individually addressed traffic indication information, whether the non-AP MLD has downlink individually addressed traffic.

3. The method according to claim 1 or 2, characterized in that one bit of the individually addressed traffic indication information corresponds to an association identifier (AID), the bit of the individually addressed traffic indication information being used to indicate whether a non-AP MLD identified by a corresponding AID has downlink individually addressed traffic.

4. The method according to any of claims 1 to 3, characterized in that the association identifiers (AIDs) corresponding to bits of the individually addressed traffic indication information are different from each other.

5. The method according to any of claims 1 to 4, characterized in that the individually addressed traffic indication information is carried in a partial virtual bitmap field of a traffic indication map element (TIM).

6. The method in accordance with any of claims 1 to 4, characterized in that the individually addressed traffic indication information is contained in a beacon frame or a TIM frame.

7. The method according to claim 6, characterized in that the beacon frame comprises special fields, and one of the special fields corresponds to a non-AP MLD that has individually addressed downlink traffic, and is used to indicate one or more links on which the non-AP MLD receives individually addressed downlink traffic.

8. The method according to any of claims 1 to 7, characterized in that an AID space used by the first AP MLD to assign an AID to the non-AP MLD associated with the first AP MLD and an AID space used by the second AP MLD to assign an AID to the non-AP MLD associated with the second AP MLD are the same.

9. The method according to claim 1 or 2, characterized in that the individually addressed traffic indication information comprises a traffic indication map (TIM) block corresponding to the first AP MLD and a TIM block corresponding to a second AP MLD, a TIM block corresponding to the first AP MLD being used to indicate whether the non-AP MLD associated with the first AP MLD has individually addressed downlink traffic, and a TIM block corresponding to a second AP MLD being used to indicate whether a non-AP MLD associated with the second AP MLD has individually addressed downlink traffic.

10. The method according to claim 9, characterized in that the individually addressed traffic indication information further comprises an index of the second AP MLD, and the second AP MLD indices are in a one-to-one correspondence with the corresponding TIM blocks of the second AP MLD.

11. The method according to claim 9 or 10, characterized in that a non-AP MLD corresponds to a bit of one of the TIM blocks, and the bit of the TIM block is used to indicate whether the non-AP MLD has individually addressed downlink traffic.

12. The method according to any of claims 9 to 11, characterized in that an AID space used by the first AP MLD to assign an AID to the non-AP MLD associated with the first AP MLD and an AID space used by the second AP MLD to assign an AID to the non-AP MLD associated with the second AP MLD are independent of each other.

13. The method according to any of claims 1, and 3 to 8, characterized in that the method further comprises: generating, by the first AP of the first AP MLD, association identifier (AID) assignment information, wherein the AID assignment information carries an AID assigned to a respective non-AP MLD, and the AID is different from another AID of the non-AP MLD; and sending, by means of the first AP of the first AP MLD, the AID assignment information.

14. The method according to any of claims 2 to 8, characterized in that the method further comprises: receiving, by means of the first STA of the non-AP MLD, the AID allocation information; and analyzing, by means of the first STA of the non-AP MLD, the received AID allocation information, to learn that the AID allocation information carries the AID allocated to the non-AP MLD, wherein the AID is different from the AID of another non-AP MLD.

15. A method for assigning an Association Identifier (AID) to a multilink device, characterized in that it comprises: generating, by means of an AP of an AP MLD, Association Identifier (AID) assignment information, wherein the AID assignment information carries an AID assigned to a non-AP MLD, the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a co-located AP MLD set of the AP, or the target AP MLD is any AP MLD in a group of sets in which the co-located AP MLD set of the AP is located; and sending, by means of the AP of the AP MLD, an Association Response Frame.

16. A method for assigning an Association Identifier (AID) to a multilink device, characterized in that it comprises: receiving, by means of a station of a non-AP MLD, AID assignment information sent by an AP of an AP MLD; and analyzing, by means of the station of the non-AP MLD, the received AID assignment information, to learn that the AID assignment information carries an AID assigned to the non-AP MLD, wherein the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a set of AP MLDs colocated by the AP, or the target AP MLD is any AP MLD in a group of sets in which the AP's colocated AP MLD set is located.

17. The method according to claim 15 or 16, characterized in that the AID assignment information is carried in an association response frame.

18. The method according to any of claims 15 to 17, characterized in that both the AP MLD and the target AP MLD belong to the set of colocated AP MLDs of AP; or both the AP MLD and the target AP MLD belong to the group of sets in which the colocated AP MLD set of AP is located, and the group of sets comprises the colocated AP MLD set of AP and a set of colocated AP MLDs of any AP other than AP1 in the colocated AP MLD set of AP1.

19. The method according to any of claims 15 to 18, characterized in that multiple stations included in a non-AP MLD share the same AID.

20. The method according to any of claims 15 to 19, characterized in that an AID space used by the AP MLD to assign an AID to a non-AP MLD associated with the AP MLD and an AID space used by the target AP MLD to assign an AID to the non-AP MLD associated with the target AP MLD are the same.

21. A method of individually addressed traffic indication applicable to multiple links, characterized in that it comprises: generating, by means of a reporting AP of an AP MLD, a management frame, wherein the management frame comprises a TIM element, and a partial virtual bitmap field of the TIM element is used to indicate whether a non-AP MLD associated with the AP MLD has individually addressed downlink traffic; and sending, by means of the reporting AP of the AP MLD, the management frame on a working link of the reporting AP.

22. A method of indicating individually addressed traffic applicable to multiple links, characterized in that it comprises: receiving, by a non-AP MLD, management frames on one or more links, wherein the one or more links comprise a first link, the first link being a link on which an AP, in a set of multiple BSSIDs, transmits from an AP MLD associated with the non-AP MLD or an AP not belonging to the set of multiple BSSIDs, the management frame comprising a TIM element, and a partial virtual bitmap field of the TIM element being used to indicate whether the non-AP MLD associated with the AP MLD has downlink individually addressed traffic; and analyzing, by the non-AP MLD, the management frame, to determine whether the non-AP MLD has downlink individually addressed traffic.

23. A communications apparatus, applied to a first AP MLD and characterized in that it comprises: a processing unit, configured to generate individually addressed traffic indication information, wherein the individually addressed traffic indication information is used to indicate whether a first non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a second non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs, and the non-transmitting AP is in a multiple BSSID set in which a first AP is located; and a transceiver unit, configured to send the individually addressed traffic indication information on a first link, wherein the first link is a working link of the first AP.

24. A communications apparatus, applied to a non-AP MLD, the non-AP MLD being the non-AP MLD associated with a first AP MLD or the non-AP MLD associated with a second AP MLD, and characterized in that it comprises: a transceiver unit, configured to receive individually addressed traffic indication information on a first link on which the communications apparatus operates, wherein the individually addressed traffic indication information is used to indicate whether the first non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether the second non-AP MLD associated with the second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs, and the non-transmitting AP is in a multiple BSSID set in which a first AP of the first AP MLD is located;and a processing unit, configured to determine, according to individually addressed traffic indication information, whether the non-AP MLD has downlink individually addressed traffic.

25. The communications apparatus according to claim 23 or 24, characterized in that one bit of the individually addressed traffic indication information corresponds to an association identifier (AID), the bit of the individually addressed traffic indication information being used to indicate whether a non-AP MLD identified by a corresponding AID has downlink individually addressed traffic.

26. The communications apparatus according to any of claims 23 to 25, characterized in that the association identifiers (AIDs) corresponding to bits of the individually addressed traffic indication information are different from each other.

27. The communications apparatus according to any of claims 23 to 26, characterized in that the individually addressed traffic indication information is carried in a partial virtual bitmap field of a TIM element.

28. The communications apparatus according to any of claims 23 to 26, characterized in that the individually addressed traffic indication information is contained in a beacon frame or a TIM frame.

29. The communications apparatus according to claim 28, characterized in that the beacon frame comprises special fields, and one of the special fields corresponds to a non-AP MLD having individually addressed downlink traffic, and is used to indicate one or more links on which the non-AP MLD receives individually addressed downlink traffic.

30. The communications apparatus according to any of claims 23 to 29, characterized in that an AID space used by the first AP MLD to assign an AID to the non-AP MLD associated with the first AP MLD and an AID space used by the second AP MLD to assign an AID to the non-AP MLD associated with the second AP MLD are the same.

31. The communications apparatus according to claim 23 or 24, characterized in that the individually addressed traffic indication information comprises a TIM traffic indication map block corresponding to the first AP MLD and a TIM block corresponding to a second AP MLD, a TIM block corresponding to the first AP MLD being used to indicate whether the non-AP MLD associated with the first AP MLD has individually addressed downlink traffic, and a TIM block corresponding to a second AP MLD being used to indicate whether a non-AP MLD associated with the second AP MLD has individually addressed downlink traffic.

32. The communications apparatus according to claim 31, characterized in that the individually addressed traffic indication information further comprises an index of the second AP MLD, and the second AP MLD indices are in a one-to-one correspondence with the corresponding TIM blocks of the second AP MLD.

33. The communications apparatus according to claim 30 or 32, characterized in that a non-AP MLD corresponds to a bit of one of the TIM blocks, and the bit of the TIM block is used to indicate whether the non-AP MLD has individually addressed downlink traffic.

34. The communications apparatus according to any of claims 31 to 33, characterized in that an AID space used by the first AP MLD to assign an AID to the non-AP MLD associated with the first AP MLD and an AID space used by the second AP MLD to assign an AID to the non-AP MLD associated with the second AP MLD are independent of each other.

35. The communications apparatus according to any of claims 23 and 25 to 30, characterized in that the processing unit is further configured to generate Association Identifier (AID) assignment information, wherein the AID assignment information carries an AID assigned to a respective non-AP MLD, and the AID is different from another AID of another non-AP MLD; and the transceiver unit is further configured to send the AID assignment information.

36. The communications apparatus according to any of claims 26 to 30, characterized in that the transceiver unit is further configured to receive AID assignment information; and the processing unit is further configured to analyze the received AID assignment information, to learn that the AID assignment information carries the AID assigned to the non-AP MLD, wherein the AID is different from the AID of the non-AP MLD associated with the second AP MLD.

37. A communications apparatus, applied to an AP MLD and characterized in that it comprises: a processing unit, configured to generate Association Identifier (AID) assignment information, wherein the AID assignment information carries an AID assigned to a non-AP MLD, the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a co-located AP MLD set of an AP, or the target AP MLD is any AP MLD in a group of sets in which the AP's co-located AP MLD set is found; and a transceiver unit, configured to send an association response frame.

38. A communications apparatus, applied to a non-AP MLD and characterized in that it comprises: a transceiver unit, configured to receive AID assignment information; and a processing unit, configured to analyze the received AID assignment information, to learn that the AID assignment information carries an AID assigned to the non-AP MLD, wherein the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a set of AP MLDs colocated from an AP, or the target AP MLD is any AP MLD in a group of sets in which the AP's colocated AP MLD set is located.

39. The communications apparatus according to claim 37 or 38, characterized in that the AID assignment information is carried in an association response frame.

40. The communications apparatus according to any of claims 37 to 39, characterized in that both the AP MLD and the target AP MLD belong to the co-located AP MLD set of AP1; or both the AP MLD and the target AP MLD belong to the group of sets in which the co-located AP MLD set of AP1 is located, and the group of sets comprises the co-located AP MLD set of AP1 and a co-located AP MLD set of any AP other than AP1 in the co-located AP MLD set of AP1.

41. The communications apparatus according to any of claims 37 to 40, characterized in that multiple stations included in a non-AP MLD share the same AID.

42. The communications apparatus according to any of claims 37 to 41, characterized in that an AID space used by the AP MLD to assign an AID to a non-AP MLD associated with the AP MLD and an AID space used by the target AP MLD to assign an AID to the non-AP MLD associated with the target AP MLD are the same.

43. A first access point multilink device (AP MLD), characterized in that it includes a first AP and a second AP, the first AP comprising a processor and a transceiver, wherein the processor is configured to generate individually addressed traffic indication information, wherein the individually addressed traffic indication information is used to indicate whether a first non-AP MLD associated with the first AP MLD has downlink individually addressed traffic and whether a second non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs, and the non-transmitting AP is in a set of multiple basic service set identifiers (BSSIDs) in which the first AP is located;and the transceiver is configured to send individually addressed traffic indication information on a first link, where the first link is a working link of the first AP.; 44. A non-access point multilink device (non-AP MLD), characterized in that it includes a first station (STA) and a second STA, the non-AP MLD being the non-AP MLD associated with a first AP MLD or the non-AP MLD associated with a second AP MLD, and the first STA comprising a processor and a transceiver, wherein the transceiver is configured to receive individually addressed traffic indication information on a first link on which the first STA operates, wherein the individually addressed traffic indication information is used to indicate whether a non-AP MLD associated with a first AP MLD has downlink individually addressed traffic and whether a non-AP MLD associated with a second AP MLD has downlink individually addressed traffic, and the second AP MLD is an AP MLD to which a non-transmitting AP belongs,and the non-transmitting AP is in a multiple BSSID set in which there is a first AP of the first AP MLD; and the processor is configured to determine, according to individually addressed traffic indication information, whether the non-AP MLD has downlink individually addressed traffic.

45. A first access point multilink device (AP MLD), characterized in that it includes a first AP and a second AP, the first AP comprising a processor and a transceiver, wherein the processor is configured to generate AID assignment information, wherein the AID assignment information carries an AID assigned to a non-AP MLD, the AID being different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD being any AP MLD in a co-located AP MLD set of an AP, or the target AP MLD being any AP MLD in a group of sets in which the co-located AP MLD set of the AP is located; and the transceiver is configured to send an association response frame.

46. ​​A non-access point multilink device (non-AP MLD), characterized in that it includes a first station (STA) and a second STA, the non-AP MLD being the non-AP MLD associated with a first AP MLD or the non-AP MLD associated with a second AP MLD, and the first STA comprising a processor and a transceiver, wherein the transceiver is configured to receive AID assignment information; and the processor is configured to analyze the received AID assignment information to learn that the AID assignment information carries an AID assigned to a non-AP MLD, wherein the AID is different from an AID of a non-AP MLD associated with a target AP MLD, and the target AP MLD is any AP MLD in a co-located AP MLD set of an AP, or the target AP MLD is any AP MLD in a group of sets in which the co-located AP MLD set of the AP is located.

47. A computer-readable storage medium, characterized in that the computer-readable storage medium stores instructions, and when the instructions are executed on a computer, the computer is enabled to perform the method in accordance with any one of claims 1 to 22.

48. A computer program product, characterized in that it comprises instructions, wherein when the instructions are executed on a computer, the computer is enabled to perform the method in accordance with any one of claims 1 to 22.

49. A chip or chip system, characterized in that it comprises an input / output interface and a processing circuit, wherein the input / output interface is configured to receive code instructions and transmit the code instructions to the processing circuit, and the processing circuit is configured to execute the code instructions to perform the method in accordance with any one of claims 1 to 22.

50. A system, characterized in that it comprises a first access point multilink device (AP MLD), a second access point multilink device (AP MLD), and a first non-access point multilink device (non-AP MLD), a second non-access point multilink device (non-AP MLD); and a first AP of the first AP MLD is configured to perform the method in accordance with any one of claims 1, 3 to 13, 15, 17 to 20, 21; and a first station of the first non-AP MLD or of the second non-AP MLD is configured to perform the method in accordance with any one of claims 2 to 14, 16 to 20, 22.

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