METHOD AND APPARATUS FOR TRANSMITTING RADIO FRAMES, AND METHOD AND APPARATUS FOR RECEIVING RADIO FRAMES.

Abstract

This application provides a method and apparatus for sending radio frames, and a method and apparatus for receiving radio frames. The first information to identify a first MLD in an MLE is included in a radio frame, so that a receiver of the radio frame obtains the first MLD information from the MLE based on this first information after receiving the radio frame. In the method, a first AP generates the radio frame including the MLE; the MLE carries the first MLD information; the MLE includes the first information, and this first information identifies the first MLD; and the first AP sends the radio frame. This application applies to a wireless local area network system compatible with next-generation IEEE 802.11ax Wi-Fi protocols, such as 802.11be (also known as the EHT protocol) and other protocols in the 802.11 family.

Description

This application relates to the field of wireless technologies and, in particular, to a method and apparatus for sending radio frames and a method and apparatus for receiving radio frames. BACKGROUND OF THE INVENTION With the development of wireless technologies, more and more wireless devices support multi-link communication. For example, devices support simultaneous communication on 2.4 gigahertz (GHz), 5 GHz, and 6 GHz frequency bands, or they support communication on different channels within the same frequency band. This improves communication speed between devices. These devices are often called multi-link devices (MLDs). Multi-link devices can be multi-link access point devices or multi-link station devices. Currently, during communication between multilink devices, one multilink device can send a radio frame containing a multilink element (MLE) to another multilink device. For example, the sender of a radio frame might be an access point (AP) on a multilink access point device. The AP might return a probe response frame in response to a probe request frame from a station (STA). By default, the MLE included in the probe response frame corresponds to the multilink access point device to which the sending AP is affiliated. This means that the information carried in the MLE is station information from the multilink access point device to which the sending AP is affiliated. However, since the AP only sends back information from the MLD where it is located within the radio frame, communication efficiency is low. If the AP needs to send back information from another MLD within the radio frame—for example, if the STA probe request frame requests information from an MLD that includes an AP corresponding to a non-transmitted Basic Service Set Identifier (BSSID) on a link where the AP is located—the way the AP sends back the radio frame is a technical problem that needs to be resolved urgently. BRIEF DESCRIPTION OF THE INVENTION This application provides a method and apparatus for sending radio frames, and a method and apparatus for receiving radio frames. The first information for identifying a first MLD in an MLE is included in a radio frame, so that a receiver of the radio frame obtains the information of the first MLD of the MLE based on the first information after receiving the radio frame. A first aspect of this application provides a method for sending radio frames, applied to WLAN communication. The method is carried out by a first access point (AP), or the method is carried out by a component (for example, a processor, a chip, or a system-on-a-chip) of a first AP. In the first aspect and possible implementations of the first aspect, an example is used for the description in which the first AP carries out the method. In the method, the first AP generates a radio frame that includes an MLE, where the MLE carries information from a first MLD, the MLE includes first information, and the first information identifies the first MLD; and the first AP sends the radio frame. Based on the technical solution described above, in the WLAN communication process, the radio frame sent by the first AP includes the MLE (Multiple Link Entity) to carry the information of the first MLD (Multiple Link Device). The MLE contains the first piece of information to identify the first MLD. Therefore, a radio frame receiver can obtain the information of the first MLD from the MLE based on this first piece of information after receiving the radio frame. In other words, after receiving the radio frame, the receiver can determine, based on this first piece of information, that the MLE corresponds to the first MLD. Therefore, the receiver can obtain, based on the MLE, information about the stations on multiple links where the first MLD is located, thus enabling the receiver to communicate with the first MLD. Furthermore, compared to an implementation where a field indirectly indicating an MLD corresponding to the MLE is carried in a location other than the MLE in the radio frame (e.g., a Basic Service Set Identifier (BSSID Index) is carried in a Multiple BSSID-Index element in a Multiple BSSID element of the radio frame, to indirectly indicate an MLD to which an AP / STA corresponding to the MLE is affiliated in the Multiple BSSID element, where the AP / STA is indicated by an SSID), in the former implementation, because the MLE includes the first information (in other words, the first information is RI 7Pnn / C7n7 / R / VIAI (carried within the MLE), the radio frame receiver can determine, based on the MLE, the MLD corresponding to the MLE, without needing an indirect indication from outside the MLE, so the radio frame receiver obtains information from stations in the first MLD. This improves communication efficiency. A second aspect of the features of this application provides a method for receiving radio frames, applied to WLAN communication. The method is carried out by a station (STA), or the method is carried out by a component (for example, a processor, a chip, or a system-on-a-chip) of an STA. In the second aspect and the possible implementations of the second aspect, an example is used for the description in which the STA carries out the method. In the method, the STA receives a radio frame from a first access point (AP), where the radio frame includes a multilink element (MLE), the MLE carries information from a first multilink device (MLD), the MLE includes the first information, and the first information identifies the first MLD; and the STA obtains the information of the first MLD from the MLE based on the first information. Based on the previous technical solution, in the WLAN communication process, the STA acts as a receiver of a radio frame. The radio frame received by the STA from the first AP includes the MLE (Multiple Link Entity) to carry the information of the first MLD (Multiple Link Device), and the MLE contains the first piece of information to identify the first MLD. Therefore, the radio frame receiver can obtain the information of the first MLD from the MLE based on the first piece of information after receiving the radio frame. In other words, after receiving the radio frame, the receiver can determine, based on the first piece of information, that the MLE corresponds to the first MLD. Therefore, the radio frame receiver can obtain, based on the MLE, information about the stations on multiple links where the first MLD is located, thus enabling the radio frame receiver to communicate with the first MLD. Furthermore, compared to an implementation where a field indirectly indicating an MLD corresponding to the MLE is carried in a location other than the MLE in the radio frame (for example, a Basic Service Set Identifier (BSSID Index) is carried in a Multiple BSSID-Index element in a Multiple BSSID element of the radio frame, to indirectly indicate an MLD to which an AP / STA corresponding to the MLE is affiliated in the Multiple BSSID element, where the AP / STA is indicated by an SSID), in the former implementation, because the MLE includes the first information (in other words, the first information is carried within the MLE), the receiver of the radio frame can determine, based on the MLE, the MLD corresponding to the MLE, without needing to obtain an indirect indication from outside the MLE.so the radio frame receiver obtains information from stations in the first MLD. This improves communication efficiency. A third aspect of the modalities of the present application provides a radio frame transmitting apparatus for WLAN communication. The apparatus may be specifically a first access point (AP) or a component (e.g., a processor, a chip, or a system-on-a-chip) of the first AP. The first AP includes a transceiver unit and a processing unit. The processing unit is configured to generate a radio frame, where the radio frame includes a multilink element (MLE), the MLE carries information from a first multilink device (MLD), the MLE includes first information, and the first information identifies the first MLD. The transceiver unit is configured to transmit the radio frame for the first AP. Based on the previous technical solution, in the WLAN communication process, the radio frame sent by the transceiver includes the MLE (Multiple Link Element) to carry the information of the first MLD (Multiple Link Device). The MLE contains the initial information to identify the first MLD. Therefore, a radio frame receiver can obtain the information of the first MLD from the MLE based on this initial information after receiving the radio frame. In other words, after receiving the radio frame, the receiver can determine, based on this initial information, that the MLE corresponds to the first MLD. Therefore, the receiver can obtain, based on the MLE, information about stations on multiple links where the first MLD is located, thus enabling the receiver to communicate with the first MLD. Furthermore, compared to an implementation where a field indirectly indicating an MLD corresponding to the MLE is carried in a location other than the MLE in the radio frame (for example, a Basic Service Set Identifier (BSSID Index) is carried in a Multiple BSSID-Index element in a Multiple BSSID element of the radio frame, to indirectly indicate an MLD to which an AP / STA corresponding to the MLE is affiliated in the Multiple BSSID element, where the AP / STA is indicated by an SSID), in the former implementation, because the MLE includes the first information (in other words, the first information is carried within the MLE), the receiver of the radio frame can determine, based on the MLE, the MLD corresponding to the MLE, without needing to obtain an indirect indication from outside the MLE.so the radio frame receiver obtains information from stations in the first MLD. This improves communication efficiency. A fourth aspect of the modalities of this application provides a radio frame receiving apparatus used in WLAN communication. The apparatus may specifically be an STA, or a component (for example, a processor, a chip, or a system-on-a-chip) of an STA. The apparatus includes a transceiver unit and a unit of RI 7Pnn / C7n7 / R / VIAI processing. The transceiver unit is configured to receive a radio frame from a first access point (AP), where the radio frame includes a multilink element (MLE). The MLE carries information from a first multilink device (MLD). The MLE includes first information, and the first information identifies the first MLD. The processing unit is configured to obtain the first MLD information from the MLE based on the first information. Based on the above technical solution, in the WLAN communication process, the radio frame receiver acts as the radio frame receiver. The radio frame received by the transceiver in the receiver includes the MLE (Multiple Link Element) to carry the information of the first MLD (Multiple Link Device), and the MLE contains the first piece of information to identify the first MLD. Therefore, the radio frame receiver can obtain the information of the first MLD from the MLE based on the first piece of information after receiving the radio frame. In other words, after receiving the radio frame, the radio frame receiver can determine, based on the first piece of information, that the MLE corresponds to the first MLD. Therefore, the radio frame receiver can obtain, based on the MLE, information about the stations on multiple links where the first MLD is located, so that the radio frame receiver can communicate with the first MLD. Furthermore, compared to an implementation where a field indirectly indicating an MLD corresponding to the MLE is carried in a location other than the MLE in the radio frame (for example, a Basic Service Set Identifier (BSSID Index) is carried in a Multiple BSSID-Index element in a Multiple BSSID element of the radio frame, to indirectly indicate an MLD to which an AP / STA corresponding to the MLE is affiliated in the Multiple BSSID element, where the AP / STA is indicated by an SSID), in the former implementation, because the MLE includes the first information (in other words, the first information is carried within the MLE), the receiver of the radio frame can determine, based on the MLE, the MLD corresponding to the MLE, without needing to obtain an indirect indication from outside the MLE.so the radio frame receiver obtains information from stations in the first MLD. This improves communication efficiency. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the first AP is not affiliated with the first MLD. Based on the previous technical solution, the MLE included in the radio frame is the information of the first MLD, and the first AP serves as the sender of the radio frame and is not affiliated with the first MLD. In other words, a device (which can be a single-link device or a multi-link access point device) where the first AP is located is a different device from the first MLD. Therefore, this solution can be applied to a RI 7Pnn / C7n7 / R / VIAI scenario in which the first AP sends information from another MLD (the first MLD). The radio frame receiver can also obtain, in a case where the radio frame receiver is not associated with the first AP, the information from the first MLD based on the radio frame sent by the first AP. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the first MLD is an MLD in which a second AP is located in the same BSSID set as the first AP. The radio frame further includes a multiple BSSID element, and the multiple BSSID element includes index information for a BSSID of the second AP, where a value of the index information for the BSSID of the second AP is the same as a value of the first information. Optionally, the description that the first MLD is an MLD in which there is a second AP in the same BSSID set as the first AP can also be expressed as: the first MLD includes a second AP in the same multiple BSSID Basic Service Set Identifier set as the first AP. Based on the previous technical solution, when the first AP is not affiliated with the first MLD, the first MLD can be specifically an MLD in which the second AP is located within the same BSSID set as the first AP. Thus, a Multiple Basic Service Set Identifier Element (referred to as a multiple BSSID element) in the radio frame sent by the first AP can carry information about the second AP. The multiple BSSID element can carry the BSSID index information of the second AP. Therefore, if the first MLD corresponding to the MLE in the radio frame includes the second AP, the BSSID index information value of the second AP in the multiple BSSID element is the same as the index information value in the MLE, indicating that the information of the second AP in the multiple BSSID element and the information carried in the MLE correspond to the same MLD (the first MLD). In a possible implementation of any of the first through fourth aspects of the modalities of this application, the MLE includes a first per-STA profile element, the first per-STA profile carries information from a third AP, and the third AP is affiliated with the first MLD. A value of a first element of the third AP is the same as a value of a first element of the second AP when the first per-STA profile element does not include the first element of the third AP. Optionally, a non-inheritance element in the first profile element by STA does not include the first element. Optionally, the first profile element per STA is a fully configured element. In other words, a Complete Profile field value in the first profile element per STA is 1. Optionally, the description that a first element value of the third AP is the same as a first element value of the second AP when the first profile element per STA does not include the first element of the third AP can also be expressed as follows: When a first element of a station (the second AP) in a multiple BSSID element carried in a radio frame sent by a reporting station (the first AP) is not present in a complete profile element of a reported station (the third AP), the first element is considered to be a portion of the reported station's complete profile element, and a first element value in the multiple BSSID element is the same as a first element value in the reported station's complete profile element.unless the reported station's full profile element contains a non-inherited element and the first element is present in the non-inherited element. Based on the previous technical solution, the first MLD can also include a third AP, different from the second AP, where the MLE includes the first profile element per STA to carry the third AP's information. Because some information from different APs within the same MLD is the same, when the first profile element per STA does not include the third AP's first element, the value of the third AP's first element is the same as the value of the second AP's first element. Therefore, the third AP's first element can inherit the second AP's first element. This makes it easier for the radio frame receiver to determine the third AP's first element based on the second AP's first element carried in the multiple BSSID element. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the MLE also includes a first field. A first value of the first field indicates that the value of the first element of the third AP is the same as the value of the first element of the second AP. Based on the previous technical solution, the MLE can also carry the first field. The first value of the first field indicates that the value of the first element of the third AP is the same as the value of the first element of the second AP. Thus, the radio frame receiver determines, based on the first field of the MLE, that the first element of the third AP can inherit the first element of the second AP. In other words, the radio frame receiver determines, based on the first field in the MLE, that the value of the first element of the third AP is the same as the value of the first element of the second AP. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the first field is located in a Multi-Link Control field in the MLE, or the first field is located in a Common Info field in the MLE. In a possible implementation of any of the first to fourth aspects of the modalities of this application, the value of the first element of the second AP is the same as the value of a first element of the first AP. Optionally, a first element of an AP in the first MLD is located in a frame body of the radio frame. Optionally, a non-inheritance element in a second AP element in the multiple BSSID element does not include the first element. Optionally, the second AP element in the multiple BSSID element is a fully configured element. In other words, a Complete Profile field value in the second AP element of the multiple BSSID element is 1. Optionally, the description that the value of the first element of the second AP is the same as the value of a first element of the first AP can also be expressed as follows: When the element of the second AP in the multiple BSSID element does not include the first element of the second AP, the value of the first element of the second AP is the same as the value of the first element of the first AP.Alternatively, the description can be expressed as: when a first carried element (information indicating the first element of the first AP) in a radio frame sent by an reporting station (the first AP) is not present in the full profile element of the second AP in the multiple BSSID element, the first element is deemed to be a portion of the full profile element of the second AP in the multiple BSSID element, and the value of the first element in the full profile element of the second AP in the multiple BSSID element is the same as the value of the first element in the radio frame, unless the full profile element of the second AP in the multiple BSSID element contains a non-inherited element and the first element is present in the non-inherited element. Based on the previous technical solution, because certain information from different APs within the same multiple BSSID set is the same, when the multiple BSSID element does not include the first element of the second AP, the value of the first element of the second AP is the same as the value of the first element of the first AP. Therefore, the first element of the second AP can inherit the first element of the first AP. This makes it easier for the receiver of the radio frame to determine the first element of the third AP based on the first element of the first AP carried in the radio frame. In a possible implementation of any of the first through fourth aspects of the modalities in this application, the first MLD includes a fourth AP. The radio frame also includes a reduced neighbor report (RNR) element. The RNR element includes information about the fourth AP and includes a second piece of information to identify the first MLD. The value of the first piece of information is the same as the value of the second piece of information. Based on the previous technical solution, the radio frame also includes the RNR element to communicate the information of the fourth AP. The RNR element includes the second piece of information to identify the first MLD to which the fourth AP is affiliated, and the value of the first piece of information is the same as the value of the second piece of information. Therefore, if the first MLD corresponding to the MLE in the radio frame includes the fourth AP, the value of the second piece of information in the RNR element to identify the first MLD to which the fourth AP is affiliated is the same as the value of the first piece of information in the MLE. This indicates that the information of the fourth AP in the RNR element and the information carried in the MLE correspond to the same MLD (the first MLD). In a possible implementation of any of the first through fourth aspects of the modalities of this application, the MLE includes a second profile element per STA, and the second profile element per STA carries information from an AP in the first MLD. A value of a first element of the AP in the first MLD is the same as the value of the first element of the first AP when the second profile element per STA does not include the first element of the AP in the first MLD. Optionally, the first MLD may include at least one of the following APs: the second AP, the third AP, and the fourth AP; or the first MLD may include another AP (for example, another neighboring AP); or the first MLD may include an AP corresponding to any profile element per STA carried in the MLE. This is not limited herein. Optionally, the first AP element in the first MLD is located in the frame body of the radio frame. Optionally, a non-inheritance element in the second profile element by STA does not include the first element. Optionally, the second profile element per STA is a fully configured element. In other words, a Complete Profile field value in the second profile element per STA is 1. Optionally, the description that a value of a first element of the AP in the first MLD is the same as the value of the first element of the first AP when the second profile element per STA does not include the first element of the AP in the first MLD can also be expressed as follows: When a first carried element (information indicating the first element of the first AP) in a radio frame sent by a notifying station (the first AP) is not present in a complete profile element of a notifying station (the AP in the first MLD), the first element is considered to be a portion of the complete profile element of the notifying station, and a value of the first element in the radio frame is the same as a value of the first element in the complete profile element of the notified station.unless the reported station's full profile element contains a non-inherited element and the first element is present in the non-inherited element. Based on the previous technical solution, the MLE includes the second profile element per STA to carry AP information in the first MLD. Because some information from the first MLD and the first AP (or an MLD containing the first AP) is the same, when the second profile element per STA does not include a first element for an AP in the first MLD, the value of the first AP element in the first MLD is the same as the value of the first AP element. Therefore, the first AP element in the first MLD can inherit the first AP element. This makes it easier for the radio frame receiver to determine the first AP element in the first MLD based on the first AP element carried in the radio frame. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the MLE also includes the first field. A second value for the first field indicates that the value of the first element of the AP in the first MLD is the same as the value of the first element of the first AP. Based on the previous technical solution, the MLE can also carry the first field. The second value of the first field indicates that the value of the first element of the AP in the first MLD is the same as the value of the first element of the first AP. Thus, the radio frame receiver determines, based on the first field of the MLE, that the first element of the AP in the first MLD can inherit the first element of the first AP. In other words, the radio frame receiver determines, based on the first field in the MLE, that the value of the first element of the AP in the first MLD is the same as the value of the first element of the first AP. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the first AP is affiliated with the first MLD. Based on the previous technical solution, the MLE included in the radio frame is the information of the first MLD, and the first AP serves as the sender of the radio frame and is affiliated with the first MLD. In other words, the first AP is one of the APs in the first MLD. Therefore, this solution can be applied to a scenario where the first AP sends the information of the MLD (the first MLD) in which the first AP is located. The receiver of the radio frame can obtain, in a case where the receiver is associated with the first AP, the information of the first MLD based on the radio frame sent by the first AP. Furthermore, compared to an implementation where the MLE of the radio frame carries, by default, the information of the MLD containing the radio frame sender and does not carry any indication information, in this solution, because the first piece of information in the MLE indicates the corresponding MLD, the radio frame receiver can determine, based on this first piece of information, that the MLD corresponding to the first MLE is the MLD containing the first AP. Additionally, the solution can also be used in a scenario where the radio frame carries MLEs corresponding to MLDs other than the radio frame sender. In other words, based on the configuration of the first piece of information, the solution is applicable to a scenario where the radio frame carries a plurality of MLEs corresponding to a plurality of MLDs (including the MLD containing the radio frame sender, i.e., the first MLD). In a possible implementation of any of the first through fourth aspects of the modalities of this application, the MLE includes the common information field, and the first information is found in the common information field. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the first piece of information is a multi-link device identifier (MLD ID) field. Optionally, the first piece of information can be another field name, for example, a multilink identifier, a multilink device index, or a multilink index. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the radio frame further includes a fragment element adjacent to the MLE. The MLE carries a first portion of the information from the first MLD, and the fragment element carries a second portion of the information from the first MLD. Based on the previous technical solution, in the WLAN communication process, a data length limit can be established for a single MLE (e.g., 255 bytes). Therefore, a case where an MLE is insufficient to carry the data of the first MLD can occur due to this length limitation. In this case, different portions of the data from the first LDM can be carried individually within the MLE, along with one or more fragment elements adjacent to the MLE, so that the data from the first MLD is transmitted completely. Furthermore, compared to an implementation where different portions of MLD information are carried in a plurality of non-adjacent subelements, i.e., carried in different locations of the MLE in the radio frame (e.g., information from the same MLD is carried in different subelements of data portions of a plurality of non-transmitted BSSID profile subelements) BSSID Profile subelement) in the multiple BSSID element of the radio frame), in the above solution, because the MLE and one or more fragment information segments are adjacent in the radio frame, the radio frame receiver can obtain information from the same MLD from the MLE and from the one or more fragment information segments adjacent to the MLE, instead of individually reading information from a plurality of non-adjacent subelements, so that the radio frame receiver obtains station information from the first MLD. This improves communication efficiency. Optionally, the number of information items included in the fragment item is 1, the fragment item includes a length field, and the length field value is less than or equal to 255. Optionally, the fragment element includes n information elements, a length field value for each information element except for the last information element in the n information elements is 255, where n is an integer greater than 1. In a possible implementation of any of the first through fourth aspects of the modalities of this application, the radio frame is a multilink probe response (ML Probe Response) frame. Based on the previous technical solution, the communication method can be applied to a multi-link probing process. After receiving a multi-link probe request (ML Probe Request) frame, the first access point (AP) can generate and send the multi-link probe response frame to execute the multi-link probing process. A fifth aspect of the modalities of this application provides a communication apparatus, including at least one processor. The at least one processor is coupled to a memory, the memory being configured to store a program or instructions. The at least one processor is configured to execute the program or instructions, such that the apparatus implements the method according to any of the first aspects or possible implementations of the first aspect, or the apparatus implements the method according to any of the second aspects or possible implementations of the second aspect. A sixth aspect of the features of this application provides a computer-readable storage medium that stores one or more computer-executable instructions. When the computer-executable instructions are executed by a processor, the processor carries out the method in accordance with any of the first aspects or possible implementations of the first aspect, or the processor carries out the method in accordance with any of the second aspects or possible implementations of the second aspect. A seventh aspect of the features of this application provides a computer program product (or referred to as a computer program) that stores one or more computer instructions. When the computer program product is executed by a processor, the processor carries out the method in accordance with either the first aspect or possible implementations of the first aspect, or the processor carries out the method in accordance with either the second aspect or possible implementations of the second aspect. An eighth aspect of the features of this application provides a system-on-a-chip. The system-on-a-chip includes at least one processor, configured to support a communication apparatus in the implementation of functions in any of the first aspect or possible implementations of the first aspect, or configured to support a communication apparatus in the implementation of functions in any of the second aspect or possible implementations of the second aspect. In one possible design, the system-on-a-chip also includes memory. The memory is configured to store computer instructions and data required by the communication device. The system-on-a-chip may consist of a single chip, or it may consist of a chip and another discrete component. Optionally, the system-on-a-chip also includes an interface circuit, which provides computer instructions and / or data to at least one processor. A ninth aspect of the modalities of this application provides a communication system. The communication system includes the communication apparatus in the third aspect and the communication apparatus in the fourth aspect, and / or the communication system includes the communication apparatus in the fifth aspect. For the technical aspects of any design from the fifth to the ninth aspect, refer to the technical aspects of the different implementations from the first to the fourth aspect. The details are not described again in this document. It can be learned from the previous technical solutions that, in the WLAN communication process, the radio frame sent by the first AP includes the MLE to carry the information of the first MLD, where the MLE contains the initial information to identify the first MLD. Therefore, the receiver of the radio frame can obtain the information of the first MLD from the MLE based on this initial information after receiving the radio frame. In other words, after receiving the radio frame, the receiver can determine, based on this initial information, that the MLE corresponds to the first MLD. Therefore, the receiver can obtain, based on the MLE, information about the stations on multiple links where the first MLD is located, thus enabling the receiver to communicate with the first MLD. Furthermore, compared to an implementation where a field indirectly indicating an MLD corresponding to the MLE is carried in a location other than the MLE in the radio frame (for example, a Basic Service Set Identifier (BSSID Index) is carried in a Multiple BSSID-Index element in a Multiple BSSID element of the radio frame, to indirectly indicate an MLD to which an AP / STA corresponding to the MLE is affiliated in the Multiple BSSID element, where the AP / STA is indicated by an SSID), in the former implementation, because the MLE includes the first information (in other words, the first information is carried within the MLE), the receiver of the radio frame can determine, based on the MLE, the MLD corresponding to the MLE, without needing to obtain an indirect indication from outside the MLE.so the radio frame receiver obtains information from stations in the first MLD. This improves communication efficiency. BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic diagram of a communication system according to one modality of this request. FIGURE 2 is a schematic diagram of multilink association according to one modality of this application. FIGURE 3 is a schematic diagram of a radio frame according to one modality of this application. FIGURE 4A is another schematic diagram of a radio frame according to one modality of this application. FIGURE 4B is another schematic diagram of a radio frame according to one modality of this application. FIGURE 5 is another schematic diagram of a communication system according to one modality of this request. FIGURE 6 is a schematic diagram of a communication method according to one modality of this request. FIGURE 7 is another schematic diagram of a radio frame according to one modality of this application. FIGURE 8 is another schematic diagram of a radio frame according to one modality of this application. FIGURE 9 is another schematic diagram of a radio frame according to one modality of this application. FIGURE 10 is another schematic diagram of a radio frame according to one modality of this application. FIGURE 11 is another schematic diagram of a radio frame according to one modality of this application. FIGURE 12 is another schematic diagram of a radio frame according to one modality of this application. FIGURE 13 is another schematic diagram of a radio frame according to one modality of this application. FIGURE 14 is another schematic diagram of a radio frame according to one modality of this application. FIGURE 15 is a schematic diagram of a communication apparatus according to one modality of this application. FIGURE 16 is another schematic diagram of a communication apparatus according to one modality of this application. DETAILED DESCRIPTION OF THE INVENTION For identical or similar parts within the modalities of this application, cross-references may be made between the modalities. Within the modalities of this application and the implementations / methods of implementation within the modalities, unless otherwise specified or a logical conflict arises, the terms and / or descriptions are consistent and may be cross-referenced between different modalities and between the implementations / methods of implementation within the modalities. Technical features in different modalities and implementations / methods of implementation within modalities may be combined to form a new modality, implementation, or method of implementation in accordance with an internal logical relationship between them. The following descriptions of modalities in this application do not constitute any limitation of the scope of protection of this application. It may be understood that, in some scenarios, certain optional features in the modalities of this application can be implemented independently without relying on another feature, such as a solution upon which the optional features are currently based, to resolve a corresponding technical problem and achieve the corresponding effects. Alternatively, in some scenarios, the optional features are combined with other features as required. Consequently, the devices provided in the modalities of this application may also implement these features or functions. Details are not described herein. In the description of this application, the term “a plurality of” means two or more of the following, unless otherwise specified. “At least one of the following items” or a similar expression thereof refers to any combination of these items, including any combination of singular items or plural items. For example, at least one item of a, b, c may mean: a, b, c, a and b, a and c, by and c, or a, by and c, where a and by and c may be singular or plural. Furthermore, to clearly describe the technical solutions in the modalities of this request, terms such as “first” and “second” are used to distinguish between the same or similar elements that provide essentially the same functions or purposes. A person skilled in the art can understand that the terms “first” and “second” do not limit a quantity or sequence of execution, and that the terms “first” and “second” do not indicate a definitive difference. Additionally, in the modalities of this request, the expressions “example” or “for example” are used to provide an example, illustration, or description. Any modality or implementation described as “example” or “for example” in the modalities of this request should not be explained as being more preferred or having more advantages than any other modality or implementation.Likewise, the use of expressions such as "example" and "for example" is intended to present a relative concept in a specific way to facilitate understanding. To facilitate understanding of the method provided in the modalities of this request, the following describes a system architecture of the method provided in the modalities of this request. It is understood that the system architecture described in the modalities of this request is intended to describe the technical solutions of the modalities of this request more clearly and does not constitute any limitation of the technical solutions provided in the modalities of this request. The technical solutions provided in this application are applicable to a WLAN scenario, for example, they are applicable to standards of an IEEE 802.11 system, for example, 802.11a / b / g, 802.11η, 802.11ac, 802.11ax, or a next generation of 802.11ax, for example, 802.11be or another next generation standard. Although the features of this application are described primarily using an example of a deployed WLAN, specifically one that implements the IEEE 802.11 standard, a person skilled in the art readily understands that aspects of this application can be extended to other networks using various standards or protocols, such as Bluetooth, high-performance wireless LAN (HIPERLAN) (a wireless standard similar to IEEE 802.11, primarily used in Europe), a wide area network (WAN), a personal area network (PAN), or other known or future networks. Therefore, the various aspects provided in this application are applicable to any suitable wireless network, regardless of coverage and wireless access protocols. Alternatively, the modalities of this application can be applied to a wireless local area network system, for example, an Internet of Things (Internet of Things) network. IoT) or a vehicle-to-everything (V2X) network. Certainly, the terms of this application are applicable to other possible communication systems, for example, a long-term evolution (LTE) system, a frequency-division duplex (FDD) LTE system, a time-division duplex (TDD) LTE system, a universal mobile telecommunications system (UMTS), a worldwide interoperability for microwave access (WiMAX) communication system, a fifth-generation (5G) communication system, and a future sixth-generation (6G) communication system. The communication systems mentioned above in this application are merely descriptive examples and are not limited to them. A general description is provided herein. Details are not described again in this document. A method and apparatus for transmitting radio frames and a method and apparatus for receiving radio frames provided in the modalities of this application may be applied to a wireless communication system. The wireless communication system may be a wireless local area network (WLAN) or a cellular network. The method may be implemented by a communication device in the wireless communication system or by a chip or processor in the communication device. The communication device may be a wireless communication device capable of transmitting in parallel over a plurality of links. For example, the communication device is called a multi-link device (MLD) or a multi-band device.Compared to a device that supports transmission through a single link, the multi-link device has higher transmission efficiency and higher throughput. FIGURE 1 is a schematic diagram of a communication system according to one modality of this request. As shown in Figure 1, the communication system primarily includes at least one multi-link access point (AP) device and at least one multi-link non-AP STA device (multi-link station device for short). The multi-link access point device and the multi-link station device may be collectively referred to as multi-link devices. The multi-link devices are described below. The multi-link device includes one or more affiliated stations (affiliated station, referred to as an affiliated STA). The affiliated STA is a logical station and can operate over a single link. The affiliated station can be an access point (AP) or a non-access point station (non-AP STA). For ease of description, in this application, a multi-link device whose affiliated station is an AP may be referred to as a multi-link AP, multi-link AP device, or multi-link AP device; and a multi-link non-AP STA device whose affiliated station is a non-AP STA may be referred to as a multi-link STA, multi-link STA device, or multi-link STA device.For ease of description, “a multilink device includes an affiliated STA” is also briefly described as “a multilink device includes an STA” in the modalities of this application. It should be noted that a multi-link device includes a plurality of logical stations, and each logical station operates on a single link, but a plurality of logical stations are permitted to operate on the same link. A link identifier mentioned below 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 is used to represent the more than one station. A link mentioned later sometimes also represents a station operating on the link. During data transmission between a multi-link AP and a multi-link STA, a link identifier can be used to identify a link or a station on a link. Before communication, the multi-link AP and the multi-link STA can negotiate or communicate with each other regarding a mapping between a link identifier and a link or station on a link. Therefore, during data transmission, a link identifier is carried to indicate a link or station on a link, instead of transmitting a large amount of signaling information for the same purpose. This reduces signaling overhead and improves transmission efficiency. In one example, a multi-link AP device might send a management frame, for instance, a beacon frame, during the establishment of a Basic Service Set (BSS). The management frame carries an element that includes a plurality of link identifier information fields, and each link identifier information field can be used to map a link identifier to a station operating on a link. Each link identifier information field includes a link identifier and further includes one or more of the following: a medium access control (MAC) address, an operation class, and a channel number, where one or more of the MAC address, the operation class, and the channel number can indicate a link.In another example, during a multilink association establishment process, the multilink AP and the multilink station negotiate multiple fields of link identifier information. In subsequent communication, the multilink AP or the multilink station can represent a station on the multilink device using a link identifier, and the link identifier can further represent one or more attributes of a station's MAC address, an operational class, and a channel number. The MAC address can alternatively be replaced by an association identifier of the multilink AP associated with the station. If a plurality of stations operate on a link, the link identifier (which is a numeric ID) represents an operational class and a corresponding channel number for the link, and also represents an identifier of a station operating on the link, for example, a MAC address or an association identifier (AID) of the station. A multi-link device can implement wireless communication using the 802.11 standard family. For example, a station that supports Extremely High Performance (EHT), or a station that supports 802.11be, or a station that supports a standard other than 802.11be, can communicate with another device. This other device may or may not be a multi-link device. The MLD without an AP in this application can be a wireless communication chip, a wireless sensor, or a wireless communication terminal. Examples of MLDs without an AP include a user terminal, a user device, an access device, a subscriber station, a subscriber unit, a mobile station, a user agent, and a user device capable of Wi-Fi communication.The user terminal can be any of various devices capable of wireless communication, such as a handheld device, a vehicle-mounted device, a portable device, an Internet of Things (IoT) device, a computing device, another processing device connected to a wireless modem, and user equipment (UE) of various forms, a mobile station (EM), a terminal, terminal equipment, a portable communication device, a handheld device, a portable computing device, an entertainment device or system, a gaming device or system, a global positioning system device, any other suitable device configured for network communication via a wireless medium, and the like. Furthermore, the MLD without an AP can support the 802.11be standard or a next-generation 802 WLAN standard.11 be. The MLD without AP can also support a plurality of WLAN standards such as 802.11ax, 802.11ac, 802.11n, 802.11g, 802.11b, and 802.11a. The AP MLD in the configurations of this application can be a device deployed in a wireless communication network to provide wireless communication functionality to a non-AP associated with the AP MLD. The AP MLD is primarily deployed in homes, within buildings, and on campuses, with a typical coverage radius of tens to hundreds of meters. However, the AP MLD can also be deployed outdoors. The AP MLD, equivalent to a bridge connecting a wired and a wireless network, is primarily configured to connect wireless network clients to each other and subsequently connect the wireless network to Ethernet. Specifically, the AP MLD can be a communication device with a Wi-Fi chip, such as a base station, router, gateway, repeater, communications server, switch, or bridge.The base station can take various forms, such as a macro base station, a micro base station, a repeater station, and so on. Furthermore, the MLD access point (AP MLD) can support the 802.11be standard or a next-generation 802.11be WLAN standard. The AP MLD can also support WLAN standards such as 802.11ax, 802.11ac, 802.11n, 802.11g, 802.11b, and 802.11a. As described above, the multi-link access point device and the multi-link station device can communicate with each other using multiple radio frames, such as an association request frame, a re-association request frame, an association response frame, a re-association response frame, and a polling response frame. Different radio frames can carry a multi-link element (MLE) to transport information from a station to a multi-link device. The MLE can also be called a multi-link information unit. The following uses a multilink device association process as an example to describe the specific implementation of an association request frame used in the association process. As shown in FIGURE 2, in a multilink establishment (or multilink association) process, a station on a multilink station device can send an association request frame to an access point on a multilink access point device, where the association request frame carries an MLE to carry information from one station on the multilink station device and information from another station on the multilink device.Similarly, an association response frame returned by the access point to the station can also carry an MLE to carry information from one current access point on the multi-link access point device and information from another access point on the multi-link device. The preceding content briefly describes the system architecture in the modalities of this request. To better understand the technical solutions of the modalities of this request, the following content is related to the modalities of this request. I. Format of an MLE Figure 3 is a schematic diagram of the format of an MLE. The MLE includes an Element ID field (for example, a value for this field might be 255, as shown in Figure 3), a Length field, an Element ID Extension field, a Multi-Link Control field, a Common Info field, and a Link Info field. The Common Info field contains common information for multiple stations on a multi-link device and information about the multi-link device itself. The Link Info field contains information for one station on each link of the multi-link device. The Multi-Link Control field contains a multi-link element type and indication information that specifies which fields are present and which are not present in the Common Info field. Furthermore, as shown in Figure 3, the link information field can also include one or more Per-STA Profile fields. Figure 3 uses an example where the number of Per-STA Profile fields is x (x is greater than 1). Each Per-STA Profile field can also include a Subelement ID field (for example, a Subelement ID field value can be 0, as shown in Figure 3), a Length field, and a Data field. In addition, as shown in FIGURE 3, the data field may also include a station control field (STA Control), a station information field (STA Info), and a station profile field (STA Profile). Furthermore, as shown in FIGURE 3, the STA profile field includes a plurality of fields. For example, the number of fields is m (x is greater than 1) in FIGURE 3. The STA profile field also includes a plurality of elements. For example, in FIGURE 3, the number of elements is n (n is greater than 1). Additionally, the STA profile field includes a non-inheritance element (if present). However, as shown in Figure 3, the length of content that the MLE can carry is limited, and the specific length of the MLE is indicated by its length field. Specifically, the length field indicates a number of octets following the length field in the MLE. For example, the length of the length field in the MLE is 8 bits, indicating a length from 0 to 255 octets. However, the length of the information to be carried in the MLE can exceed 255 octets, so a single MLE is insufficient to carry the information for the multilink device. Furthermore, the information for a station on each link of the multilink device is carried in the profile subelement per STA within the link information field, and the length of each profile per STA is also limited. For example, the length of the profile length field per STA is 8 bits, so the data field can contain a maximum of 255 bytes. However, the information for a station on each link can exceed 255 bytes, so a single profile per STA is insufficient to carry the information for one station on each link. II. Multiple BSSIDs The current 802.11 standard supports the multiple Basic Service Set Identifier Set (BSSID) feature (also known as multiple BSSID sets). A key function of multiple BSSID sets is to create multiple virtual access points (APs) on a single device to serve different types of STAs. Multiple virtual APs can be managed centrally to reduce management costs. A multiple BSSID set can be a combination of several cooperative access points (APs), all of which use the same operating class, channel number, and antenna port. Typically, within a multiple BSSID set, there is one AP corresponding to a transmitted BSSID and several APs corresponding to non-transmitted BSSIDs. Information about a multiple BSSID set (i.e., a multiple BSSID element) is carried in a management frame (such as a beacon frame, probe response frame, or neighbor report) sent by an AP with a transmitted BSSID. Information about a non-transmitted BSSID AP is derived from the multiple BSSID element or similar information in the received beacon frame, probe response frame, or neighbor report. Furthermore, in a multi-BSSID technology, a physical AP can be virtualized into a plurality of logical APs. Each virtual AP manages a BSSID. The different virtual APs typically have different SSIDs and permissions, such as security mechanisms or transmission opportunities. A BSSID corresponding to a virtual AP among the plurality of APs obtained through virtualization is configured as a Transmitted BSSID. The virtual AP can be referenced as a Transmitted AP. The BSSIDs corresponding to other virtual APs are configured as Non-Transmitted BSSIDs. These virtual APs can be referred to as Non-Transmitted APs. In general, a plurality of APs in a multi-BSSID can also be understood as a plurality of cooperative AP devices obtained by virtualizing a single AP device. Only an AP whose BSSID is a Transmitted BSSID can send a beacon frame and a probe response frame.If a probe request frame. RI 7Pnn / C7n7 / R / YIAI sent by a STA is intended for an AP whose BSSID is not a broadcast BSSID in a multiple BSSID set. The AP whose BSSID is the broadcast BSSID needs to respond with a probe response frame. The beacon frame sent by the AP whose BSSID is the broadcast BSSID includes a multiple BSSID element, and APs whose BSSIDs are not broadcast BSSIDs cannot send a beacon frame. The association identifiers (AIDs) assigned by multiple virtual APs to stations managed by those same virtual APs share a space, meaning that the AIDs assigned to stations managed by multiple virtual BSSIDs cannot be the same. Optionally, as shown in Table 1, the multiple BSSID element includes the following fields: Element ID, Length, Maximum BSSID Indicator, and Subelements. A value (n) in the Maximum BSSID Indicator field is used to calculate a maximum of 2Λη (i.e., 2 to the power of n) BSSIDs included in the multiple BSSID set. The optional subelements include information for each untransmitted BSSID. A receiving end can calculate a value for each BSSID in the multiple BSSID set based on a reference BSSID, the Maximum BSSID Indicator, and a BSSID Index. Each BSSID comprises 48 bits.The most significant bit (48-n) value of each BSSID in the multiple BSSID set is equal to the most significant bit (48-n) value of the reference BSSID, and the least significant bit (n) value of each BSSID in the multiple BSSID set is obtained by performing a modulo operation on the sum of the least significant bit (n) value of the reference BSSID and the BSSID index value x multiplied by 2Λη. The reference BSSID (the transmitted BSSID) is carried in a BSSID field in a MAC header of a frame (for example, a beacon frame) that includes the multiple BSSID element. For the specific calculation method, refer to the 802.11-2016 standard. Table 1 Element ID Length Indicator BSSID Maximum Optional Subelements Octet 1 1 1 Variable Table 2 shows the “optional sub-elements” listed in Table 1. Table 2 Subelement ID Extensible Name 0 Profile BSSID not transmitted Non-extensible 1-220 Reserved Subelement ID Extensible Name 221 Provider-Specific Defined by Provider 222-255 Reserved Optionally, in Table 2, the non-broadcast basic service set identifier profile (non-broadcast BSSID profile) includes a list of items for one or more APs or directional multi-gigabit stations (DMG STA) that have non-broadcast BSSIDs. Optionally, in Table 2, the non-transmitted BSSID profile includes, among others, the following elements. 1. For each non-transmitted BSSID, a non-transmitted BSSID capacity element and a variable number of elements are included in a beacon frame. 2. A service set identifier (SSID) element and a multiple BSSID index element are included. The multiple BSSID index element includes a BSSID index field. 3. If the multiple BSSID element is carried in the beacon frame, a First Missing PDCP Sequence Number (FMS Descriptor) element is also included. 4. The following elements are not included: the Timestamp and Beacon Interval fields, the Direct Sequence Spread Spectrum Parameter Set (DSSS), the Independent Basic Service Parameter Set (IBSS), Country, Channel Switch Announcement, Extended Channel Switch Announcement, Wide Bandwidth Channel Switch, Transmit Power Envelope, and Supported Operating Classes, IBSS DFS, ERP Information, High Throughput Capabilities (HT Capabilities), HT Operation, VHT Capabilities, VHT OperationGIS beacon compatibility, short beacon interval, GIS capabilities, GIS operation (11 ah), and similar elements. These elements have the same values ​​as those of the transmitted AP BSSID. 5. An optional non-inherited element is included as the last element. This non-inherited element includes the Element ID and Element ID Extension numbers for a series of elements that the non-passed BSSID cannot inherit from the passed BSSID. The specific content of these elements is omitted here. Specifically, as shown in Table 3, the non-inherited element includes the following fields: Element ID, Length, Element ID Extension, Element ID List, and Element ID Extension List. The Element ID Extension number is present only when the Element ID field value is 255. Table 3 Non-inherited element 1 octet 1 octet 1 octet One or more octets One or more octets Element ID Length Element ID Extension Element ID List Element ID Extension List One example of implementing the multiple BSSID element frame format to transport the multiple BSSID set can be shown in FIGURE 4A. As shown in FIGURE 4A, the radio frame structure includes two adjacent multiple Basic Service Set Identifier (multiple BSSID) elements. Each multiple BSSID element includes the following fields: an Element ID field (for example, an Element ID field value of 71, as shown in FIGURE 4A), a Length field, a Max BSSID Indicator field, and a Nontransmitted BSSID Profile subelement (or Nontransmitted BSSID Profile). There are zero or more Nontransmitted BSSID Profile subelement fields. In FIGURE 4A, an example is used where the number of Nontransmitted BSSID Profile subelement fields is i (where i is greater than 1). Furthermore, as shown in FIGURE 4A, the untransmitted BSSID profile subelement i (BSS i) includes a subelement ID field (e.g., a subelement ID field value of 0), a length field, and a data field. Additionally, as shown in FIGURE 4A, the data field includes a Nontransmitted BSSID Capability element, a Service Set Identifier (SSID) element, a Multiple BSSID-Index element, one or more elements, and a noninherited element (if present). In the example shown in FIGURE 4A, the Nontransmitted BSSID Profile subelement i in the first Multiple BSSID element includes elements 1 through L (L is greater than 1), and the Nontransmitted BSSID Profile subelement i in the second Multiple BSSID element includes element (L+1) through element Y (Y is greater than L). In the implementation example shown in FIGURE 4A, in the Data portion of the non-transmitted BSSID profile sub-element, the stations (STA / AP) corresponding to “Element 1” to “Element L” in the Data portion can be identified by the Basic Service Set Identifier Index (BSSID Index) in the Multiple BSSID-Index element. Specifically, the multiple BSSID element carries information from a plurality of virtual APs within a multiple BSSID set to which an AP belongs. The length field occupies 8 bits, indicating that a maximum of 255 bytes can be carried. However, the length of the information for the plurality of virtual APs can exceed 255 bytes. Therefore, a plurality of multiple BSSID elements is used to carry the information for the plurality of virtual APs. As shown in Figure 4A, the first multiple BSSID element carries the first portion of information from BSS 1 to BSS i, and the second multiple BSSID element carries the remaining portion of information from BSS i to BSS (i+1). The contents of the two multiple BSSID elements can be concatenated to obtain the information from BSS 1 to BSS (i+1). The information for each BSS begins with an untransmitted BSSID capacity element. III. Combination of multiple BSSIDs and multi-link In the case of a device that supports both multi-link communication and a multiple BSSID set, there can be a multiple BSSID on each link, and APs from different multiple BSSID sets can form an MLD, but the transmitted BSSIDs are not necessarily in the same MLD. For example, FIGURE 5 shows an example of a device structure implementation. For example, in the scenario shown in FIGURE 5, four MLD APs are included. MLD AP1 includes one AP numbered BSSID-1x (corresponding to link L1), one AP numbered BSSID-2y (corresponding to link L2), and one AP numbered BSSID-3 (corresponding to link L3). MLD AP2 includes one AP numbered BSSID-1z (corresponding to link L1), one AP numbered BSSID-2x (corresponding to link L2), and one AP numbered BSSID-4y (corresponding to link L4). MLD AP3 includes one AP numbered BSSID-1y (corresponding to link L1), one AP numbered BSSID-2z (corresponding to link L2), and one AP numbered BSSID-4x (corresponding to link L4). MLD AP4 includes one AP numbered BSSID-4z (corresponding to link L4). It should be noted that a link number and a link identifier in the figure are not the same concept.The link identifier represents a group of the following elements to identify a specific AP: an operational set, a channel number, and a MAC address (or a BSSID) of an AP. For example, an AP ending with the number “x” corresponds to a broadcast BSSID, and an AP not ending with “x” (e.g., “y” or “z”) corresponds to a non-broadcast BSSID. Specifically, multiple BSSID set 1 on link 1 includes one broadcast BSSID BSSID-1x and the non-broadcast BSSIDs BSSID-1z and BSSID-1y; multiple BSSID set 2 on link 2 includes one broadcast BSSID BSSID-2x and the non-broadcast BSSIDs BSSID-2z and BSSID-2y; link 3 includes BSSID-3 (which is considered not to belong to any multiple BSSID set, without needing to distinguish between a broadcast BSSID and a non-broadcast BSSID). and the multiple set of BSSID 4 on link 4 includes one transmitted BSSID BSSID-4x and the non-transmitted BSSIDs BSSID-4z and BSSID-4y. For ease of description, an “AP corresponding to BSSID-n” is referred to hereafter as “AP-n” for short. In the scenario shown in FIGURE 5, n can be 1x, 1y, 1z, 2x, 2y, 2z, 3, 4x, 4y, 4z, or similar. In some implementation processes, in the implementation scenario shown in FIGURE 5, if AP-1x serves as the reporting AP (a sender of a radio frame), the radio frame sent by AP-1x can carry an MLE corresponding to an MLD (AP MLD1) in which AP-1x is located. The MLE carries station information for a plurality of stations (including AP-2 and AP-3) on AP MLD1. A frame format for the MLE carried in the radio frame can be the same as in the implementation process shown in FIGURE 3. Generally, the MLE carried in the radio frame is, by default, an MLE corresponding to an MLD in which the reporting AP is located. Therefore, a receiver of the radio frame determines (without needing to include additional indication information) that the MLE carried in the radio frame corresponds to the MLD in which the reporting AP is located. For example, AP-1x can return a probe response frame in response to a probe request frame from a station (STA). By default, an MLE included in the probe response frame corresponds to a multilink access point device (AP MLD1) to which the AP-1x sending the probe response frame is affiliated. This means that the information carried in the MLE is station information from the multilink access point device to which the AP sending the radio frame is affiliated (information from stations AP-2y and AP-3). However, in this scenario, it is possible for AP-1x to feed back information from another MLD in the radio frame. For example, the STA polling request frame requests information from an MLD (AP MLD2 or AP MLD3) to which an AP corresponding to a non-transmitted Basic Service Set Identifier (non-transmitted BSSID) is affiliated on a link where AP-1x is located. In this case, the way in which AP-1x feeds back the radio frame is an urgent technical issue that needs to be resolved. ri zcnn / cznz / R / YiAi Figure 6 is a schematic diagram of a communication method according to this request. The method includes the following steps. As shown in Figure 6, the communication method refers to the transmission of a radio frame. Therefore, the communication method can also be referred to as a radio frame sending method or a radio frame receiving method. S101: A radio frame transmitter generates a radio frame. In this mode, the radio frame sending device generates the radio frame in step S101. The radio frame includes an MLE, the MLE carries information from a first MLD, the MLE includes the first information, and the first information identifies the first MLD. The radio frame emitter can be a first AP, or a component (e.g., a processor, a chip, or a system of chips) of the first AP. S102: The radio frame transmitter sends the radio frame. In this mode, after generating the radio frame in step S101, the radio frame transmitter sends the radio frame in step S102. Consequently, a radio frame receiver receives the radio frame in step S102. The radio frame emitting device can be an STA or a component (e.g., a processor, a chip, or a chip system) of the STA. Optionally, the first AP can perform pre-transmission processing on the radio frame and send, in step S102, a processing result obtained through pre-transmission processing. For example, pre-transmission processing could include encryption, encoding, and similar operations. Consequently, the STA can receive the processing result (obtained by the first AP using pre-transmission processing on the radio frame) and perform pre-reception processing on the processing result in step S102 to obtain the radio frame. For example, pre-reception processing could include decryption, decoding, and similar operations. S103: The radio frame receiving apparatus obtains the information from the first MLD of the MLE based on the first information. In one possible implementation, the radio frame is a Multi-Link Probe Response (ML Probe Response) frame. Specifically, the communication method shown in Figure 6 can be applied to a multi-link probing process. After receiving a Multi-Link Probe Request (ML Probe Request) frame, the first AP can generate and send the Multi-Link Probe Response frame to execute the multi-link probing process. In one possible implementation, in the MLE included in the radio frame sent by the first AP in step S102, the first piece of information is a Multi-Link Device Identifier (MLD ID) field. Specifically, the first piece of information could alternatively be another field name, for example, a Multi-Link Identifier, a Multi-Link Device Index, or a Multi-Link Index. For example, the MLE included in the radio frame sent by the first AP in step S102 includes a common information field, and the first piece of information can be located in this common information field. Figure 7 is an example of an MLE format implementation in the radio frame. For definitions of the elements / fields included in Figure 7, refer to the descriptions above on Figure 3. The first piece of information can be located in the "Common Info" field of a "Multi-Link Element" within a "Frame Body" in the radio frame. In Figure 7, an example is used where the first piece of information is called the "Multi-Link Identifier (MLD ID)." In one possible mode, at step S102, the MLE carried in the radio frame corresponds to the first MLD identified by the first information. The first AP serves as a notifying AP (a sender) of the radio frame, and an association relationship between the first AP and the first MLD can be implemented differently. For example, a first information value (MLD ID field) of 0 indicates that the MLE in the radio frame carries information from the MLD in which the first AP is located. A first information value (MLD ID field) of any other value indicates that the MLE in the radio frame carries information from a different MLD. Optionally, “another MLD” can be an MLD co-located with the first AP. The “MLD co-located” with the first AP can indicate an MLD located on the same physical device as the first AP. Furthermore, the first AP can know, without needing to perform signal detection or measurement, an attribute of the MLD co-located with the first AP. Optionally, the “other MLD” can be an MLD to which another AP in the same multiple BSSID set as the first AP is affiliated, or it can be an MLD to which another AP carried in an RNR element in the radio frame by the first AP is affiliated, or it can be another implementation. This is not limited herein. The following descriptions use specific examples. Implementation 1: The first AP is not affiliated with the first MLD. Specifically, the MLE included in the radio frame sent by the first AP in step S102 is the information of the first MLD, and the first AP serves as the sender of the radio frame and is not affiliated with the first MLD. In other words, a device (which can be a single-link device or a multi-link access point device) where the first AP is located is a different device from the first MLD. Therefore, this solution can be applied to a scenario where the first AP sends information from another MLD (the first MLD). The receiver of the radio frame can also obtain the information of the first MLD in step S103, in the case where the receiver of the radio frame is not associated with the first AP, based on the radio frame sent by the first AP. For example, the scenario shown in FIGURE 5 is used as an implementation example. For example, AP-1x serves as the notifying AP (the first AP to send the radio frame in step S102). When the first AP is not affiliated with the first MLD, the first MLD can be an AP MLD other than AP MLD1, for example, AP MLD2, AP MLD3, and AP MLD4. Furthermore, if the first AP is not affiliated with the first MLD, the first MLD may have multiple implementations. Descriptions using specific examples are provided below. In one possible Implementation 1 mode, the first MLD is an MLD in which there is a second AP in the same BSSID set as the first AP. For example, the scenario shown in Figure 5 is used as an implementation example. For instance, AP-1x serves as the notifying AP (the first AP to send the radio frame in step S102). When the first AP is not affiliated with the first MLD, the first MLD can be an MLD to which an AP is affiliated, where the AP and AP-1x are located on the same link. In other words, the first MLD is either AP MLD2, to which AP-1z is affiliated, or AP MLD3, to which AP-1y is affiliated. In this implementation, the radio frame sent by the first AP in step S102 also includes a multiple BSSID element. The multiple BSSID element includes index information for one BSSID of the second AP, and a value in the index information for the second AP's BSSID is the same as a value in the first BSSID. Optionally, the description that the first MLD is an MLD in which a second AP is located in the same BSSID set as the first AP can also be expressed as: The first MLD includes a second AP in the same multiple BSSID Basic Service Set Identifier set as the first AP. Specifically, when the first AP is not affiliated with the first MLD, the first MLD may be the same MLD with which the second AP is located in the same BSSID set as the first AP. Therefore, the Multiple Basic Service Set Identifier (Multiple BSSID Element, or multiple BSSID Element) in the radio frame sent by the first AP may carry information about the second AP. The multiple BSSID Element may carry the BSSID index information of the second AP. Thus, if the first MLD corresponding to the MLE in the radio frame includes the second AP, the BSSID index information value of the second AP in the multiple BSSID Element is the same as the index information value in the MLE, indicating that the information of the second AP in the multiple BSSID Element and the information carried in the MLE correspond to the same MLD (the first MLD). The format shown in FIGURE 8 is an example implementation of the multiple BSSID element included in the radio frame sent by the first AP in step S102. For definitions of the elements / fields included in FIGURE 8, refer to the descriptions above on FIGURE 4A. Specifically, when a non-transmitted BSSID profile subelement (BSS 1) shown in FIGURE 8 corresponds to a BSS of the second AP, a multiple BSSID-Index element in a data portion of the non-transmitted BSSID profile subelement (BSS 1) carries a Basic Service Set Identifier (BSSID Index) to identify a BSSID index of the second AP.In this case, in the radio frame sent in step S102, the first AP sets the value of the BSSID index information of the second AP in the multiple BSSID element to be the same as the value of the first information in the MLE, to indicate that the information of the second AP in the multiple BSSID element and the information carried in the MLE correspond to the same MLD (the first MLD). A format shown in FIGURE 9 is another example of the implementation of the Multiple BSSID element and the Multi-Link element (MLE) included in the radio frame sent by the first AP in step S102. For definitions of the elements / fields included in FIGURE 9, see the descriptions in FIGURE 3 and FIGURE 4A. Specifically, as shown in FIGURE 9, the two fields denoted by dashed boxes have the same value, meaning that a value in the “BSSID Index” field in the Multiple BSSID element is the same as a value in the “MLD ID” field in the Multi-Link element. In one possible implementation, the MLE included in the radio frame sent by the first AP in step S102 includes a first profile element per STA. This first profile element per STA carries information from a third AP, and the third AP is affiliated with the first MLD. The value of a first element for the third AP is the same as the value of a first element for the second AP when the first profile element per STA does not include the first element of the third AP. For example, the scenario shown in Figure 5 is used as an implementation example. For instance, AP-1x serves as the notifying AP (the first AP to send the radio frame in step S102). When the first AP is not affiliated with the first MLD, the first MLD can be an MLD to which an AP is affiliated, where the AP and AP-1x are located on the same link. In other words, the first MLD is either AP MLD2, to which AP-1z is affiliated, or AP MLD3, to which AP-1y is affiliated. Assuming the first MLD is AP MLD2, to which AP-1z is affiliated, the second AP can be AP-1z, and the third AP can be either AP-2x or AP-4y. Optionally, a non-inheritance element in the first profile element by STA does not include the first element. Optionally, the first profile element per STA is a fully configured element. In other words, a Complete Profile field value in the first profile element per STA is 1. Optionally, the description that a first element value of the third AP is the same as a first element value of the second AP when the first profile element per STA does not include the first element of the third AP, can also be expressed as follows: When a first element of a station (the second AP) in the multiple BSSID element carried in a radio frame sent by a reporting station (the first AP) is not present in a complete profile element of a reported station (the third AP), the first element is considered to be a portion of the reported station's complete profile element, and a first element value in the multiple BSSID element is the same as a first element value in the reported station's complete profile element.unless the reported station's full profile element contains a non-inherited element and the first element is present in the non-inherited element. Specifically, the first MLD can also include a third AP, different from the second AP, where the MLE includes the first profile element per STA to carry the third AP's information. Because some information from different APs within the same MLD is the same, when the first profile element per STA does not include the third AP's first element, the value of the third AP's first element is the same as the value of the second AP's first element. Therefore, the third AP's first element can inherit the second AP's first element. This makes it easier for the radio frame receiver to determine the third AP's first element in step S103 based on the second AP's first element carried in the multiple BSSID element. Furthermore, the MLE included in the radio frame sent by the first AP in step S102 may also include a first field. A first field value indicates that the first element value of the third AP is the same as the first element value of the second AP. Specifically, the MLE may also carry the first field. The first field value indicates that the first element value of the third AP is the same as the first element value of the second AP. Thus, the radio frame receiver determines, based on the first field of the MLE in step S103, that the first element of the third AP can inherit the first element of the second AP. In other words, the radio frame receiver determines, based on the first field in the MLE in step S103, that the first element value of the third AP is the same as the first element value of the second AP. Additionally, the first field is located in a Multi-Link Control field in the MLE, or the first field is located in the Common Info field in the MLE. The format shown in FIGURE 10 is an example implementation of the Multiple BSSID element and the Multi-Link element (MLE) included in the radio frame sent by the first AP in step S102. For definitions of the elements / fields included in FIGURE 10, see the descriptions in FIGURE 3 and FIGURE 4A. In FIGURE 10, for example, the first field is labeled “Inheritance Mode” (whereas the first field may be labeled differently). The first field is located in the “Common Info” field of the “Multi-Link element (MLE)”. The format shown in FIGURE 11 is another implementation example. Unlike the format shown in FIGURE 10, the first field in the format shown in FIGURE 11 is located in the “Multi-Link Control” field of the “Multi-Link Element (MLE)”. In a possible implementation, the value of the first element of the second AP is the same as the value of the first element of the first AP. Optionally, the first AP element in the first MLD is located in the frame body of the radio frame. Optionally, a non-inheritance element in a second AP element in the multiple BSSID element does not include the first element. Optionally, the second AP element in the multiple BSSID element is a fully configured element. In other words, a Complete Profile field value in the second AP element of the multiple BSSID element is 1. Optionally, the description that the value of the first element of the second AP is the same as the value of the first element of the first AP can also be expressed as follows: When the element of the second AP in the multiple BSSID element does not include the first element of the second AP, the value of the first element of the second AP is the same as the value of the first element of the first AP.Alternatively, the description can be expressed as: when a first carried element (information indicating the first element of the first AP) in a radio frame sent by an reporting station (the first AP) is not present in the full profile element of the second AP in the multiple BSSID element, the first element is considered to be a portion of the full profile element of the second AP in the multiple BSSID element, and the value of the first element in the full profile element of the second AP in the multiple BSSID element is the same as the value of the first element in the radio frame, unless the full profile element of the second AP in the multiple BSSID element contains a non-inherited element and the first element is present in the non-inherited element. Based on the previous technical solution, because certain information from different APs within the same multiple BSSID set is the same, when the multiple BSSID element does not include the first element of the second AP, the value of the first element of the second AP is the same as the value of the first element of the first AP. Therefore, the first element of the second AP can inherit the first element of the first AP. This makes it easier for the radio frame receiver to determine the first element of the third AP in step S103 based on the first element of the first AP carried in the radio frame. In another possible implementation of Implementation 1, the first MLD includes a fourth AP, where the information from the fourth AP is carried in an RNR element in the radio frame. The radio frame sent by the first AP in step S102 also includes the RNR element, where the RNR element contains information about the fourth AP and includes the second piece of information to identify the first MLD. The value of the first piece of information is the same as the value of the second piece of information. Specifically, the radio frame also includes the RNR element to communicate information about the fourth AP. The RNR element includes the second piece of information to identify the first MLD to which the fourth AP is affiliated, and the value of the first piece of information is the same as the value of the second piece of information.Therefore, in the case where the first MLD corresponding to the MLE in the radio frame includes the fourth AP, the value of the second piece of information in the RNR element to identify the first MLD to which the fourth AP is affiliated is the same as the value of the first piece of information in the MLE, to indicate that the information of the fourth AP in the RNR element and the information carried in the MLE correspond to the same MLD (the first MLD). Optionally, the first MLD may include at least one of the following APs: the second AP, the third AP, and the fourth AP; or the first MLD may include another AP (for example, another neighboring AP); or the first MLD may include an AP corresponding to any profile element per STA carried in the MLE. This is not limited herein. FIGURE 12 shows an example of RNR element implementation. Specifically, for an AP, the reduced neighbor report element is carried in a management frame, for example, a beacon frame or a probe response frame. During this scan, a STA station receives an association frame sent by the AP to obtain information about surrounding APs and subsequently selects a suitable AP for association. It should be noted that, in this and subsequent modes, a neighbor access point can specifically be an access point around an access point (referred to in this description as the target access point) that sends the Reduced Neighbor Report element (RNR element). For example, the neighbor AP is an AP on a different link in an MLD AP where the target AP is located. In another example, the neighbor AP is an AP adjacent to the target AP. Another example is that the neighbor AP is an AP detected in the target AP's operational area. Yet another example is that the neighbor AP is an AP co-located with the target AP. Alternatively, the AP can be defined in other ways. This is not specifically limited herein. Specifically, the RNR element carries information about one or more neighboring APs on a specific channel. Figure 12 shows a frame format for the RNR element, which includes an Element ID field and a Length field indicating the length of the information carried. Additionally, each RNR element carries one or more Neighbor AP info fields. The Neighbor AP info field can also be called the Neighbor AP info field for short. The information included in each Neighbor AP info field is described below with reference to Figure 12. Each Neighbor AP info field includes the following information. 1. Target beacon transmission times information header (TBTT info Header). 2. Operating class field: This indicates the operating class to which an operating channel of a neighboring reporting AP belongs. Values ​​such as 0 and 255 are reserved for this field. 3. Channel Number field: This indicates a channel number corresponding to an operational channel of a neighboring reporting AP. In this field, a value of 0 is reserved. Additionally, the STA can determine a specific AP channel location within a frequency band based on the operational class field and the channel number field. 4. TBTT info set field: which includes one or more TBTT info fields. Additionally, a frame format for each TBTT info field can be implemented in the implementation shown in FIGURE 12. As shown in FIGURE 12, each TBTT info field can include the following information. a. Neighbor AP TBTT Offset: This field indicates the offset between a beacon transmission time for a BSS from a reporting neighbor AP and a beacon transmission time for a BSS to send the report. The offset is measured in time units (TU), with one TU equal to 1024 microseconds or 1 millisecond. A value of 254 indicates an offset of 254 TU or higher, and a value of 255 indicates an unknown offset. The number of bits occupied by this field can be 1. b. BSS Identifier Field (BSSID): Indicates a BSS identifier corresponding to the reporting BSS. The number of octets occupied by this field can be 0 or 6. This field is optional. c. Short SSID field: Indicates a service set identifier to which the BSS belongs. The number of octets this field occupies can be 0 or 4. This field is optional. d. BSS Parameter field: Indicates a related BSS parameter. The number of octets occupied by this field can be 0 or 1. This field is optional. e. 20 MHz Power Spectral Density (PSD) field: Indicates a maximum transmit power spectral density. This field is optional. The number of octets occupied by this field can be 0 or 1. f. Multilink Device Parameters (MLD Parameters) field: Indicates an MLD-related parameter. The number of octets this field occupies can be 0 or 3. The MLD Parameters field includes the following subfields: A Multi-Link Device Identifier (MLD ID) subfield, which occupies 8 bits and indicates an identifier for an MLD AP; a Link Identifier (Link ID) subfield, which occupies 4 bits and indicates a link identifier corresponding to a reporting neighbor AP; a BSS Parameters Change Count subfield, which occupies 8 bits and indicates a BSS parameter change count; and a Reserved subfield, which occupies 4 bits. When a key change occurs on the reporting AP, the BSS parameter change count is incremented. Otherwise, the BSS parameter change count remains unchanged. Therefore, when the “Multi-link Device Identifier (MLD ID) subfield” in the Multi-link Device Parameters field shown in FIGURE 12 corresponds to the first MLD in which the fourth AP is located, the “Multi-link Device Identifier (MLD ID) subfield” in the Multi-link Device Parameters field identifies the first MLD with which the fourth AP is affiliated. In this case, in the radio frame sent in step S102, the first AP sets a value of the “Multilink Device Identifier (MLD ID) subfield” in the Multilink Device Parameters field (MLD Parameters) to be the same as the value of the first information in the MLE, to indicate that the first MLD to which the fourth AP is affiliated, identified by the “Multilink Device Identifier (MLD ID) subfield” in the Multilink Device Parameters field (MLD Parameters), and the information carried in the MLE correspond to the same MLD (the first MLD). Furthermore, the MLE included in the radio frame sent by the first AP in step S102 includes a second profile element per STA, and the second profile element per STA carries information from an AP in the first MLD. The value of a first AP element in the first MLD is the same as the value of the first AP element when the second profile element per STA does not include the first AP element in the first MLD. Optionally, the first AP element in the first MLD is located in the frame body of the radio frame. Optionally, a non-inheritance element in the second profile element by STA does not include the first element. Optionally, the second profile element per STA is a fully configured element. In other words, a Complete Profile field value in the second profile element per STA is 1. Optionally, the description that a first element value of the AP in the first MLD is the same as the first element value of the first AP when the second profile element per STA does not include the first AP element in the first MLD, can also be expressed as follows: When a first carried element (information indicating the first element of the first AP) in a radio frame sent by a reporting station (the first AP) is not present in a complete profile element of a reporting station (the AP in the first MLD), the first element is considered to be a portion of the reporting station's complete profile element, and the first element value in the radio frame is the same as the first element value in the reported station's complete profile element.unless the reported station's full profile element contains a non-inherited element and the first element is present in the non-inherited element. Based on the previous technical solution, the MLE includes the second profile element per STA to carry the AP information in the first MLD. Because some information in the first MLD is the same as that of the first AP (or an MLD containing the first AP), when the second profile element per STA does not include the first AP element in the first MLD, the value of the first AP element in the first MLD is the same as the value of the first AP element. Therefore, the first AP element in the first MLD can inherit the first AP element. This makes it easier for the radio frame receiver to determine the first AP element in the first MLD at step S103 based on the first AP element carried in the radio frame. Furthermore, the MLE can also include the first field. A second value in the first field indicates that the value of the first element of the AP in the first MLD is the same as the value of the first element of the first AP. Specifically, the MLE can also carry the first field. The second value in the first field indicates that the value of the first element of the AP in the first MLD is the same as the value of the first element of the first AP. Thus, the radio frame receiver determines, based on the first field of the MLE in step S103, that the first element of the AP in the first MLD can inherit the first element of the first AP. In other words, the radio frame receiver determines, based on the first field in the MLE in step S103, that the value of the first element of the AP in the first MLD is the same as the value of the first element of the first AP. Optionally, for an implementation process for the first field, refer to the descriptions above (including FIGURE 10 and FIGURE 11). The details are not described again herein. Implementation 2: The first AP is affiliated with the first MLD. In Implementation 2, the MLE included in the radio frame is the information for the first MLD, and the first AP serves as the sender of the radio frame and is affiliated with the first MLD. In other words, the first AP is one of the APs in the first MLD. Therefore, this solution can be applied to a scenario where the first AP sends the information for the MLD (the first MLD) in which the first AP is located. The receiver of the radio frame can obtain, in step S103, in a case where the receiver is associated with the first AP, the information for the first MLD based on the radio frame sent by the first AP. Furthermore, compared to a mode where the MLE of the radio frame carries, by default, the information of the MLD containing the radio frame sender and does not carry any indication information, in this solution, because the first piece of information in the MLE indicates the MLD corresponding to the MLE, the radio frame receiver can determine in step S103, based on the first piece of information, that the MLD corresponding to the first MLE is the MLD containing the first AP. Additionally, the solution can also be used in a scenario where the radio frame carries MLEs corresponding to MLDs other than the radio frame sender. In other words, based on the configuration of the first piece of information, the solution is applicable to a scenario where the radio frame carries a plurality of MLEs corresponding to a plurality of MLDs (including the MLD containing the radio frame sender, i.e., the first MLD). For example, the scenario shown in FIGURE 5 is used as an implementation example. For example, AP-1x serves as the notifying AP (the first AP to send the radio frame in step S102). When the first AP is affiliated with the first MLD, the first MLD can be AP MLD1, meaning that the information from the first MLD carried in the MLE includes information from stations AP-2 and AP-3. In conclusion, based on the description of Implementation 1 or Implementation 2, it can be learned that the radio frame sent by the first AP in step S102 includes the MLE to carry the information of the first MLD, where the MLE contains the first piece of information to identify the first MLD. Therefore, the receiver of the radio frame can obtain the information of the first MLD from the MLE based on the first piece of information in step S103 after receiving the radio frame. In other words, after receiving the radio frame, the receiver can determine, based on the first piece of information, that the MLE corresponds to the first MLD in step S103.In contrast to a mode where the radio frame cannot carry an MLE corresponding to a different MLD because the MLE in the radio frame carries, by default, information about the MLD where the radio frame sender is located and does not carry indication information, in this solution, based on the adjustment of the initial information, the MLE carried in the radio frame can carry an MLE corresponding to an MLD other than the one that sent the radio frame. Therefore, the receiver of the radio frame can obtain, based on the MLE, information from stations on multiple links where the first MLD is located, allowing the receiver to communicate with the first MLD. Furthermore, compared to an implementation where a field indirectly indicating an MLD corresponding to the MLE is carried in a location other than the MLE in the radio frame (e.g., the Basic Service Set Identifier (BSSID Index) is carried in the Multiple BSSID-Index element in the Multiple BSSID element of the radio frame, to indirectly indicate an MLD to which an AP / STA corresponding to the MLE in the Multiple BSSID element is affiliated, where the AP / STA is indicated by an SSID), in the former mode, because the MLE includes the first information (in other words, the first information is carried within the MLE), the radio frame receiver can determine, based on the MLE, the MLD corresponding to the MLE in step S103, without needing to obtain an indirect indication from outside the MLE, to obtain station information from the first MLD in step S103.This improves communication efficiency. ri zcnn / cznz / R / YiAi In the implementation scenario shown in FIGURE 5, if AP-1x serves as the notifying AP (the sender of the radio frame), the radio frame sent by AP-1x can carry MLEs corresponding to MLDs (AP MLD2 and AP MLD3) in which other APs are located in the same multiple BSSID set (the multiple BSSID set 1 on link 1) as AP-1x, one of the MLEs carries station information from a plurality of stations (including AP-2x and AP4y) in AP MLD2, and the other MLE carries station information from a plurality of stations (including AP-2z and AP-4x) in AP MLD3. An MLE is used as an example to transport station information from a plurality of stations (including AP-2x and AP-4y) in AP MLD2. The MLE is transported in the data portion of the non-transmitted BSSID profile subelement (BSS i, i.e., a BSS corresponding to AP-1z) in the format shown in FIGURE 4A. For example, the MLE is located in any one of “Element 1” through “Element L”. Limited by the length of each "Element," when the AP MLD2 includes a large amount of information, a plurality of non-broadcast BSSID profile sub-elements can be used to carry the MLE corresponding to the AP MLD2. For an implementation process, see the implementation example shown in FIGURE 4B. Compared to the implementation process in FIGURE 4A, FIGURE 4B describes in detail that the "L Element" in the data portion of the non-broadcast BSSID profile sub-element carries one portion of the MLE (for an example of MLE implementation, see the description in FIGURE 3), and the "L+1 Element" in the data portion of another non-broadcast BSSID profile sub-element carries the other portion of the MLE.From the description above in FIGURE 4A, it follows that the Basic Service Set Identifier (BSSID Index) in the Multiple BSSID Index element can identify a station (STA / AP) corresponding to “Element 1” through “Element L” in the Data portion. In other words, in the mode example shown in FIGURE 4B, a BSSID value in the Multiple BSSID Index element is an AP-1z BSSID, indirectly indicating that the MLE carried by “Element L” and “Element L+1” belongs to the MLD to which AP-1z is affiliated. However, in the implementation example shown in FIGURE 4B, in a case where the MLE carried in the radio frame needs to be fragmented due to its large length, because the transmission in the case of fragmentation of the MLE carried in the multiple BSSID element is complex, the analysis complexity is high for the radio frame receiver. RI 7Pnn / C7n7 / R / YIAI Therefore, in the communication method shown in FIGURE 6, the above problem can be solved by improving the information carried in the radio frame. In one possible implementation, the radio frame sent by the first AP in step S102 also includes a fragment element adjacent to the MLE. The MLE carries the first portion of the first MLD's information, and the fragment element carries the second portion of the first MLD's information. Specifically, in WLAN communication, the length of information that can be carried by an MLE can be fixed (for example, 255 bytes). Therefore, a case where an MLE is insufficient to carry the information of the first MLD can occur due to this length limitation. In this case, different portions of the information from the first LDM can be carried separately in the MLE, with one or more fragment elements adjacent to the MLE, so that the information from the first LDM is transmitted completely. Furthermore, compared to an implementation where different portions of MLD information are carried in a plurality of non-adjacent subelements, i.e., carried in different locations within the MLE in the radio frame (e.g., information from the same MLD is carried in different subelements of data portions from a plurality of non-transmitted BSSID profile subelements (non-transmitted BSSID profile subelement) in the multiple BSSID element of the radio frame), in the above solution, because the MLE and one or more fragment information segments are adjacent in the radio frame, the radio frame receiver can obtain the information from the same MLD from the MLE and the one or more fragment information segments adjacent to the MLE in step S103, instead of separately reading the information from a plurality of non-adjacent subelements.In order to obtain station information from the first MLD at step S103. This improves communication efficiency. In comparison to the implementation process shown in Figure 4B, in the previous solution, fragmentation is not necessary when the information carried in the MLE within the radio frame is relatively long (for example, when the MLE length exceeds 255 bytes). Because the MLE is no longer located within the multiple BSSID element as shown in Figure 4B, but rather outside of it, fragmentation is not required, as the multiple BSSID element is not excessively long. For example, when the MLE is fragmented separately, the MLE can be fragmented into an MLE and one or more fragment elements. The format shown in FIGURE 13 is an example implementation of the multiple BSSID element, the Multi-Link element (MLE), and the Fragment element included in the radio frame sent by the first AP in step S102. For definitions of the elements / fields included in FIGURE 13, see the descriptions in FIGURE 3 and FIGURE 4A. In the example shown in FIGURE 13, the number of information items included in the fragment item is 1, the fragment item includes a length field, and the length field value is less than or equal to 255. The format shown in FIGURE 14 is another example of implementation. Unlike the format shown in FIGURE 13, the format shown in FIGURE 14 includes a plurality of fragment elements. In the example shown in FIGURE 14, the fragment element includes n information elements, a length field value for each information element except the last information element in the n information elements is 255, where n is an integer greater than 1. The above describes this request from the perspective of the methods, and what follows describes this request from the perspective of the devices. Figure 15 is a schematic diagram of a communication apparatus 1500 according to one embodiment of this application. The communication apparatus 1500 includes a processing unit 1501 and a transceiver unit 1502. In one mode, the communication apparatus 1500 can be specifically a radio frame sending apparatus, configured to implement the radio frame sending method in the mode shown in FIGURE 6. The processing unit 1501 and the transceiver unit 1502 can be configured to carry out the following process. The 1501 processing unit is configured to generate a radio frame, where the radio frame includes a multilink element (MLE), the MLE carries information from a first multilink device (MLD), the MLE includes first information, and the first information identifies the first MLD. The 1502 transceiver unit is configured to send the radio frame for a first AP. Based on the previous technical solution, in the WLAN communication process, the radio frame sent by the 1502 transceiver unit includes the MLE to carry the information of the first MLD, where the MLE contains the initial information to identify the first MLD. Therefore, a receiver of the radio frame can obtain the information of the first MLD from the MLE based on the initial information after receiving the radio frame. RI 7Pnn / C7n7 / R / YIAI In other words, after receiving the radio frame, the receiver can determine, based on the initial information, that the MLE corresponds to the first MLD. Therefore, the receiver can obtain, based on the MLE, information from stations on multiple links where the first MLD is located, thus enabling the receiver to communicate with the first MLD. Furthermore, compared to an implementation where a field indirectly indicating an MLD corresponding to the MLE is carried in a location other than the MLE in the radio frame (for example, a Basic Service Set Identifier (BSSID Index) is carried in a Multiple BSSID-Index element in a Multiple BSSID element of the radio frame, to indirectly indicate an MLD to which an AP / STA corresponding to the MLE is affiliated in the Multiple BSSID element, where the AP / STA is indicated by an SSID), in the former implementation, because the MLE includes the first information (in other words, the first information is carried within the MLE), the receiver of the radio frame can determine, based on the MLE, the MLD corresponding to the MLE, without needing to obtain an indirect indication from outside the MLE.so the radio frame receiver obtains information from stations in the first MLD. This improves communication efficiency. In another configuration, the communication apparatus 1500 can alternatively be a radio frame receiving apparatus, configured to implement the radio frame reception method in the configuration shown in FIGURE 6. The processing unit 1501 and the transceiver unit 1502 can be configured to carry out the following process. The 1502 transceiver unit is configured to receive a radio frame from a first access point (AP), where the radio frame includes a multilink element (MLE), the MLE carries information from a first multilink device (MLD), the MLE includes first information, and the first information identifies the first MLD. The 1501 processing unit is configured to obtain the first MLD information from the MLE based on the first information. Based on the previous technical solution, in the WLAN communication process, the radio frame receiver acts as the radio frame receiver. The radio frame received by the 1502 transceiver unit in the receiver includes the MLE (Multiple Link Encoder) to carry the information of the first MLD (Multiple Link Device), and the MLE contains the first piece of information to identify the first MLD. Therefore, the radio frame receiver can obtain the information of the first MLD from the MLE based on the first piece of information after receiving the radio frame. In other words, after receiving the radio frame, the frame receiver... RI 7Pnn / C7n7 / R / YIAI radio can determine, based on the initial information, that the MLE corresponds to the first MLD. Therefore, the radio frame receiver can obtain, based on the MLE, information from stations on a plurality of links where the first MLD is located, so that the radio frame receiver communicates with the first MLD. Furthermore, compared to an implementation where a field indirectly indicating an MLD corresponding to the MLE is carried in a location other than the MLE in the radio frame (for example, a Basic Service Set Identifier (BSSID Index) is carried in a Multiple BSSID-Index element in a Multiple BSSID element of the radio frame, to indirectly indicate an MLD to which an AP / STA corresponding to the MLE is affiliated in the Multiple BSSID element, where the AP / STA is indicated by an SSID), in the former implementation, because the MLE includes the first information (in other words, the first information is carried within the MLE), the receiver of the radio frame can determine, based on the MLE, the MLD corresponding to the MLE, without needing to obtain an indirect indication from outside the MLE.so the radio frame receiver obtains information from stations in the first MLD. This improves communication efficiency. In a possible implementation, the first AP is not affiliated with the first MLD. In one possible implementation, the first MLD is an MLD in which a second AP is located within the same BSSID set as the first AP. The radio frame also includes a multiple BSSID element, and the multiple BSSID element includes index information for a BSSID of the second AP, where a value in the index information of the second AP's BSSID is the same as a value in the first BSSID. Optionally, the description that the first MLD is an MLD in which there is a second AP in the same BSSID set as the first AP can also be expressed as: The first MLD includes a second AP in the same multiple BSSID Basic Service Set Identifier set as the first AP. In one possible implementation, the MLE includes a first profile element per STA (Per-STA profile). This first profile per STA carries information from a third AP, and the third AP is affiliated with the first MLD. When the first profile element per STA does not include a first element from the third AP, a value for the first element of the third AP is the same as a value for a first element of the second AP. In one possible implementation, the MLE also includes a first field. A first value in the first field indicates that the value of the first element of the third AP is the same as the value of the first element of the second AP. In a possible implementation, the first field is located in a Multi-Link Control field in the MLE, or the first field is located in a Common Info field in the MLE. In a possible implementation, the value of the first element of the second AP is the same as the value of a first element of the first AP. Optionally, a first element of an AP in the first MLD is located in a frame body of the radio frame. In one possible implementation, the first MLD includes a fourth AP. The radio frame also includes a Reduced Neighbor Report (RNR) element. The RNR element includes information about the fourth AP and a second piece of information to identify the first MLD. The value of the first piece of information is the same as the value of the second piece of information. In one possible implementation, the MLE includes a second profile element per STA, and this second profile element carries AP information in the first MLD. When the second profile element per STA does not include the first AP element in the first LDM, the value of the first AP element in the first LDM is the same as the value of the first AP element. Optionally, the first MLD may include at least one of the following APs: the second AP, the third AP, and the fourth AP; or the first MLD may include another AP (for example, another neighboring AP); or the first MLD may include an AP corresponding to any profile element per STA carried in the MLE. This is not limited herein. Optionally, the first AP element in the first MLD is located in the frame body of the radio frame. In one possible implementation, the MLE also includes the first field. A second value for the first field indicates that the value of the first element of the PA in the first MLD is the same as the value of the first element of the first AP. In a possible implementation, the first AP is affiliated with the first MLD. In a possible implementation, the MLE includes a common information field, and the first information is found in the common information field. In a possible implementation, the first piece of information is a multi-link device identifier (MLD ID) field. Optionally, the first piece of information can be another field name, for example, a multilink identifier, a multilink device index, or a multilink index. In one possible implementation, the radio frame also includes a fragment element adjacent to the MLE. The MLE carries the first portion of the information from the first MLD, and the fragment element carries the second portion of the information from the first MLD. Optionally, the number of information items included in the fragment item is 1, the fragment item includes a length field, and the length field value is less than or equal to 255. Optionally, the fragment element includes n information elements, a length field value for each information element except for the last information element in the n information elements is 255, where n is an integer greater than 1. In one possible implementation, the radio frame is a multilink probe response (ML Probe Response) frame. It should be noted that the 1500 communication device can be further configured to perform the other modes described above and achieve the corresponding beneficial effects. For more details, please refer to the descriptions of the modes above. These details are not described again herein. Figure 16 is a schematic diagram of a communication apparatus 1600 structure according to one embodiment of this application. The communication apparatus 1600 includes a processor 1601 and a transceiver 1602. The 1600 communication device can be a radio frame transmitter, a radio frame receiver, or a chip in a radio frame transmitter or a radio frame receiver. FIGURE 16 shows only the main components of the communication apparatus 1600. In addition to the processor 1601 and the transceiver 1602, the communication apparatus may also include a memory 1603 and an input / output apparatus (not shown). The processor 1601 is configured primarily to: process a communication protocol and communication data, control the entire communication apparatus, execute a software program, and process software program data. The memory 1603 is configured primarily to store the software program and data. The transceiver 1602 may include a radio frequency circuit and an antenna. The radio frequency circuit is configured primarily to: perform the conversion between a baseband signal and a radio frequency signal, and process a radio frequency signal. The antenna is configured primarily to receive and transmit a radio frequency signal in the form of electromagnetic waves. The input / output device, for example, a touchscreen, display, or keyboard, is configured primarily to receive data entered by a user and send data to the user. The processor 1601, the transceiver 1602, and the memory 1603 can be connected via a communication bus. Once the communication device is switched on, the 1601 processor can read the The RI 7Pnn / C7n7 / R / YIAI software program in memory 1603 interprets and executes software program instructions and processes software program data. When data needs to be sent wirelessly, the processor 1601 performs baseband processing on the data to be sent and then outputs a baseband signal to the radio frequency circuit. The radio frequency circuit performs radio frequency processing on the baseband signal and then transmits a radio frequency signal in the form of electromagnetic waves via the antenna. When data is sent to the communication device, the radio frequency circuit receives the radio frequency signal via the antenna, converts the radio frequency signal back into a baseband signal, and sends the baseband signal to the processor 1601. The processor 1601 converts the baseband signal back into data for processing. In any of the above designs, the 1601 processor can include a communication interface to implement receive and transmit functions. For example, the communication interface can be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing the receive and transmit functions can be separate or integrated together. The transceiver circuit, interface, or interface circuit can be configured to read and write code / data, or to transmit or transfer signals. In any of the preceding designs, the 1601 processor can store instructions. The instructions can be a computer program. The computer program is executed on the 1601 processor, so that the 1600 communication device can carry out the method described in the previous method modalities. The computer program can be fixed in the 1601 processor. In this case, the 1601 processor can be implemented in hardware. In one embodiment, the 1600 communication apparatus may include a circuit for implementing a transmit, receive, or communicate function in any of the above method embodiments. The processor and communication interface described herein may be implemented in 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 communication interface can be manufactured using various Cl technologies, for example, a complementary metal oxide semiconductor (CMOS), an N-channel metal-oxide semiconductor (NMOS), a positive channel metal oxide semiconductor (P-channel metal oxide semiconductor). RI 7Pnn / C7n7 / R / YIAI PMOS), a bipolar junction transistor (bipolar junction transistor, BJT), a bipolar CMOS (BICMOS), silicon germanium (SIGe), and gallium arsenide (GaAs). In another implementation, the radio frequency circuit and antenna can be arranged independently of the baseband processor. For example, in a distributed scenario, the radio frequency circuit and antenna can be located remotely and independently of the communication device. The communication device can be a standalone device or part of a larger device. For example, the communication device can be: (1) a stand-alone integrated circuit IC, a chip or a system or subsystem of chips; (2) an assembly comprising one or more integrated circuits, wherein, optionally, the assembly of integrated circuits may further include a storage component for storing data and instructions; (3) an ASIO, for example, a modem (Modem); (4) a module that can be embedded in another device; (5) a receiver, a smart terminal, a wireless device, a handheld device, a mobile unit, a vehicle-mounted device, a cloud device, an artificial intelligence device; or (6) another device, or the like. In an implementation process, the 1601 processor may be configured to perform, for example but not limited to, baseband-related processing; and the 1602 transceiver may be configured to perform, for example but not limited to, radio frequency reception and transmission. The above components may be arranged separately on independent chips, or at least some or all of the components may be arranged on a single chip. For example, the processor may be divided into an analog baseband processor and a digital baseband processor. The analog baseband processor and the transceiver may be integrated on a single chip, and the digital baseband processor may be arranged independently on a separate chip. With the ongoing development of integrated circuit technologies, more components may be integrated onto a single chip.For example, the baseband digital processor may be integrated on the same chip as a plurality of application processors (for example, but not limited to, a geometry processor and a multimedia processor). Such a chip may be called a system-on-a-chip (SOC). Whether the components are arranged independently on different chips or integrated into one or more chips usually depends on the specific design requirements of a product. A specific form of implementation of the above components is not limited in this embodiment of the present invention. RI 7Pnn / C7n7 / R / YIAI The methods described in this application also provide 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 carries out the method in any of the above methods. The modalities of this application also provide a software product. When the software product runs on a computer, the computer is permitted to carry out the method in any of the above modalities. The embodiments of this application further provide a communication 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 via the interface circuit, to enable the device to carry out the method in any of the above embodiments. The embodiments of this application further provide a WLAN communication system, including a radio frame transmitter and a radio frame receiver. The radio frame transmitter and the radio frame receiver can implement the method in any of the above embodiments. The steps of the method or algorithm described in combination with the content disclosed in this application may be implemented by hardware, or they may be implemented by a processor 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 that the processor can read information from the storage medium and write information to the storage medium.The storage medium can certainly be part of the processor. The processor and storage medium can be arranged in an ASIC. Furthermore, the ASIC can be located in a core network interface device. The processor and storage medium can also exist as discrete components within the core network interface device. RI 7Pnn / C7n7 / R / YIAI A person skilled in the art should be aware that in 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, where the communication medium includes any means that facilitates the transmission of a computer program from one location to another. The storage medium may be any available medium accessible to a general-purpose or dedicated computer. Although this application is described with reference to modalities, in a process of implementing this application claiming protection, a person skilled in the art may understand and implement another variation of the disclosed modalities by viewing the accompanying drawings, the disclosed content, and the appended claims. In the claims, “comprising” does not exclude any other component or step, and “a” does not exclude a plurality of them. A single processor or other unit may implement several functions listed in the claims. Some measures are listed in dependent claims that differ from one another, but this does not mean that these measures cannot be combined to produce improved effects. The objectives, technical solutions, and beneficial effects of this application are described in more detail in the specific implementations above. 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 substitution, or improvement made based on the technical solutions in this application will be included within its scope of protection.

Claims

1. A method of sending radio frames, characterized in that it comprises: generating, by a first access point (AP), a radio frame, wherein the radio frame comprises a multilink element (MLE), the MLE carrying information from a first multilink device (MLD), wherein the MLE comprises a multilink device identifier, MLD ID field, and the MLD ID field identifies the first MLD, wherein the first AP is not affiliated with the first MLD, wherein the first MLD is an MLD in which a second AP is in the same BSSID set as the first AP; and sending, by the first AP, the radio frame.

2. A method for receiving radio frames, characterized in that it comprises: receiving, from a first access point (AP), a radio frame, wherein the radio frame comprises a multilink element (MLE), the MLE carrying information from a first multilink device (MLD), wherein the MLE comprises a multilink device identifier, MLD ID field, and the MLD ID field identifies the first MLD, wherein the first AP is not affiliated with the first MLD, wherein the first MLD is an MLD in which there is a second AP in the same BSSID set as the first AP; and obtaining the information of the first MLD from the MLE based on the MLD ID field.

3. The method according to claim 1 or 2, characterized in that the radio frame further comprises a multiple BSSID element, the multiple BSSID element comprises index information of a BSSID of the second AP, and a value of the index information of the BSSID of the second AP is the same as a value of the first information.

4. The method according to claim 3, characterized in that the MLE comprises a first profile element per STA, the first profile element per STA carries information from a third AP, and the third AP is affiliated to the first MLD; and when the first profile element per STA does not comprise a first element of the third AP, a value of the first element of the third AP is the same as a value of a first element of the second AP.

5. The method according to claim 4, characterized in that the MLE further comprises a first field, and a first value of the first field indicates that the value of the first element of the third PA is the same as the value of the first element of the second AP.

6. The method according to claim 5, characterized in that the first field is located in a multi-link control field of the MLE; or the first field is located in a common information field of the MLE.

7. The method in accordance with any of claims 3 to 6, characterized in that the value of the first element of the second AP is the same as the value of a first element of the first AP.

8. The method according to claim 1 or 2, characterized in that the first MLD comprises a fourth AP; and the radio frame further comprises a reduced neighbor report RNR element, the RNR element comprising information from the fourth AP and comprising second information to identify the first MLD, and a value of the second information is the same as a value of the first information.

9. The method according to any of claims 1 to 8, characterized in that the MLE comprises a second profile element per STA, and the second profile element per STA carries information from an AP in the first MLD; and when the second profile element per STA does not comprise a first element of the AP in the first LDM, a value of the first element of the AP in the first LDM is the same as the value of the first element of the first AP.

10. The method according to claim 9, characterized in that the MLE further comprises the first field, and a second value of the first field indicates that the value of the first element of the PA in the first MLD is the same as the value of the first element of the first AP.

11. The method according to any of claims 1 to 10, characterized in that the MLE comprises the common information field, and the MLD ID field is located in the common information field.

12. The method according to any of claims 1 to 11, characterized in that the radio frame further comprises a fragment element adjacent to the MLE; and the MLE carries a first portion of the information from the first MLD, and the fragment element carries a second portion of the information from the first MLD.

13. The method according to any of claims 1 to 12, characterized in that the radio frame is a multilink probe response frame.

14. A radio frame sending apparatus, characterized in that the apparatus comprises a transceiver unit and a processing unit, and the apparatus is configured to carry out the method in accordance with any of claims 1 and 3 to 13.

15. A radio frame receiving apparatus, characterized in that the apparatus comprises a transceiver unit and a processing unit, and the apparatus is configured to carry out the method according to any of claims 2 to 13.

16. A multi-link access point (AP) device, characterized in that it comprises the radio frame emitting apparatus in accordance with claim 14.

17. A multilink device (MLD) without an access point (not AP), characterized in that it comprises the radio frame sending apparatus in accordance with claim 15.

18. A communication apparatus, characterized in that it comprises at least one processor coupled to a memory, wherein the memory is configured to store a program or instructions; and the at least one processor is configured to execute the program or instructions, such that the apparatus implements the method in accordance with any one of claims 1 to 13.

19. A program, characterized in that when the program is executed on a computer, the computer is enabled to carry out the method in accordance with any of claims 1 to 13.

20. A computer-readable storage medium, characterized in that the computer-readable storage medium stores computer instructions, and when the computer instructions are executed, the method is carried out in accordance with any one of claims 1 to 13.

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