METHOD AND APPARATUS FOR SOUNDING CHANNELS

Abstract

This application provides a method and apparatus for channel scanning. The method includes: A first communication device sends a first frame to a second communication device, where the first frame is used to instruct the second communication device to perform a channel scan on a portion of the antennas of the first communication device. The first communication device sends a second frame to the second communication device, where the second frame is used by the second communication device to perform the channel scan on the portion of the antennas. The first communication device receives a third frame from the second communication device, where the third frame is used to indicate the result of performing the channel scan on the portion of the antennas.Based on the previous technical solution, the first communication device can indicate to the second communication device a set of antennas on which the second communication device needs to perform channel measurement, instead of performing channel surveys on all antennas and returning the results. This can reduce the overhead of channel status information.

Description

METHOD AND APPARATUS FOR SOUNDING CHANNEL SOUNDING This application claims priority to Chinese patent application No. 202010135651.7, filed with the National Intellectual Property Administration of China on March 2, 2020, entitled NETWORK SECURITY PROTECTION METHOD AND PROTECTION DEVICE, which is incorporated herein by reference in its entirety. FIELD OF INVENTION This application relates to the field of communications and, more specifically, to a method and apparatus for channel sounding. BACKGROUND OF THE INVENTION The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard discusses a next-generation Extremely High Throughput (EHT) working group for IEEE 802.11ax, and considers the introduction of higher bandwidth (e.g., 320 MHz) and more streams (e.g., 16 spatial streams) in a next-generation wireless local area network (WLAN). For EHT, throughput is to be improved by increasing the number of spatial streams. However, due to a limitation in the capacity of a wireless device, a single access point (AP) can barely provide 16 spatial streams. To solve the above problems, a multi-panel multiple input multiple output (MP MIMO) technology has emerged. MP MIMO means that a wireless device (e.g., a base station in a cellular network, an AP in a WLAN, or a terminal device) is formed by interconnecting a plurality of panels. A plurality of transceiver antennas are mounted on each panel. That is, the antenna resources of a wireless device are dispersed across a plurality of panels that are close or far from each other. MP MIMO can reduce the deployment costs and complexity of numerous antennas and improve scalability, network coverage capacity, and channel gain of multiple input multiple output (MIMO). MP MIMO provides a viable solution for utilizing more streams or antenna resources for a next-generation WLAN. However, regardless of whether the antenna resources are centralized or located on a plurality of panels, a technical requirement for using MIMO technology in WLAN is a channel probing process. That is, the AP can serve one or more stations (STAs) in a MIMO manner through a plurality of antennas only after a non-AP station (non-AP STA) completes channel probing with the AP and feedbacks a channel probing result. More channel state feedback information is required if higher bandwidth and more spatial streams are introduced. This results in higher feedback overhead. Therefore, how to reduce channel state information overload becomes an urgent problem to be solved. BRIEF DESCRIPTION OF THE INVENTION This application provides a channel probing method and apparatus, to reduce the overhead of feedback of channel state information. According to a first aspect, this application provides a channel scanning method. The method includes: A first communication device sending a first frame to a second communication device, where the first frame is used to instruct the second communication device to perform channel scanning on an antenna portion of the first communication device. The first communication device sends a second frame to the second communication device, where the second frame is used by the second communication device to perform channel scanning on the antenna portion. The first communication device receives a third frame from the second communication device, where the third frame is used to indicate a result of performing channel scanning on the antenna portion. Optionally, the antenna portion may be a predetermined antenna that can communicate well with the second communication device, for example, it may be an antenna that is in predetermined antennas of the first communication device and that can communicate well with the second communication device. Optionally, the antenna portion may be a default antenna for communicating with the second communication device. Accordingly, there are many ways in which the first frame indicates the front of the antennas. For example, the first frame indicates, based on one or more panel identifiers, that the second communication device perform a channel scan on an antenna corresponding to the one or more panel identifiers. In another example, the first frame indicates, based on one or more AP identifiers, that the second communication device perform a channel scan on an antenna corresponding to the one or more AP identifiers. In another example, the first frame uses an index directly indicating an antenna to indicate the antennas portion. In another example, the first frame uses an index of a start antenna and an index of an end antenna to indicate the antennas portion. In another example, the first frame uses an index of a start antenna and an index of an end antenna to indicate the antennas portion. Based on the foregoing technical solution, the first communication device / n / zznz / q / YiAi may indicate to the second communication device a portion of the antennas on which the second communication device should perform channel measurement, and the second communication device performs channel survey only on a corresponding panel and returns the channel survey result. This may reduce the feedback overhead of channel status information compared to the case of performing channel survey on all antennas of the first communication device and feedback the channel survey results each time. With reference to the first aspect, in one possible implementation, before the first communication device receives the third frame from the second communication device, the method further includes: The first communication device sends a fourth frame to the second communication device. The fourth frame is used to instruct the second communication device to send the third frame to the first communication device. Based on the previous technical solution, the first communication device can activate, based on the fourth frame, at least a second communication device to simultaneously feed back a third frame. This helps improve the efficiency of channel scanning. With reference to the first aspect or any of the possible implementations above, in another possible implementation, before the first communication device sends the first frame to the second communication device, the method further includes: The first communication device sends a training frame to the second communication device, where the training frame is used to perform channel sounding on all antennas of the first communication device. The first communication device receives a feedback frame from the second communication device. The first communication device determines the portion of the antennas based on the feedback frame. Based on the previous technical solution, a set of antennas for communication with the second communication device can be predetermined based on actual channel conditions or similar. This helps increase the probability of successful subsequent communication between the first communication device and the second communication device. With reference to the first aspect or any of the possible implementations above, in another possible implementation, before the first communication device sends the training frame to the second communication device, the method further includes: The first communication device sends a pre-training frame to the second communication device. The pre-training frame is used to instruct the second communication device to perform a channel scan on all antennas of the first communication device. Based on the previous technical solution, the second communication device can be instructed in advance to prepare for channel scanning, so that the second communication device can prepare for channel scanning in a timely manner. This helps improve the efficiency of channel scanning. With reference to the first aspect or any of the possible implementations above, in another possible implementation, before the first communication device receives the feedback frame from the second communication device, the method further includes: The first communication device sends a wake-up frame to the second communication device. The wake-up frame is used to instruct the second communication device to send the feedback frame to the first communication device. With reference to the first aspect or any of the possible implementations above, in another possible implementation, the first frame includes a first field. The first field is used to indicate a panel portion of the first communication device, and the antenna portion includes an antenna corresponding to the panel portion. Optionally, the first field can be used to carry a panel bitmap. The panel bitmap is used to indicate the portion of the panels of the first communication device. For example, when the antennas of the first communication device are distributed across panels 1 and 4, four bits in the panel bitmap can be used to represent the four panels. For example, 1001 indicates that the antennas of panel 1 and panel 4 are the antennas on which channel scanning is to be performed this time. Optionally, different values ​​in the first field may be used to represent different combinations of panels. For example, when the antennas of the first communication device are distributed across panels 1 through 4, and the first field includes four bits, a value of 1111 in the first field represents panels 1 through 3, and a value of 1010 in the first field represents panels 1 and 2. Optionally, the first field can directly indicate an index of a panel. In the above technical solution, a portion of the panels of the first communication device is indicated to indirectly indicate a portion of the antennas on which channel scanning is to be performed. In other words, the above technical solution can be applied to a channel scanning scenario for a communication device configured with multiple panels. With reference to the first aspect or any of the possible implementations above, in another possible implementation, the first frame includes a first field. The first field / n / zznz / q / YiAi is used to carry an antenna index, and the antenna index is used to indicate the antenna portion. Optionally, the first frame uses an index that directly indicates an antenna to indicate the antenna part. Optionally, the first frame uses an index of a start antenna and an index of an end antenna to indicate the antenna part. Optionally, the first frame uses an index of an initial antenna and a number of antennas to indicate the antenna part. With reference to the first aspect or any of the possible implementations above, in another possible implementation, the first frame further includes a second field. The second field is used to indicate that the first field is used to indicate a portion of the panels of the first communication device or carry an antenna index. That is, the first communication device can notify the second communication device that a current scenario is an MP MIMO scenario. In this way, communication between the first and second communication devices can adapt to different scenarios. With reference to the first aspect or any of the possible implementations above, in another possible implementation, the first frame includes a third field. The third field is used to indicate that the first frame is a frame of an extremely high-performance EHT variant. Optionally, the third field may be one or more bits from a voiced dialog token field. For example, the third field includes a standard control field that includes bits from a scope field and a HE field in the polling dialog box field. When a standard control field value is 00, it indicates that the first frame is a VHT variant frame; when a standard control field value is 01, it indicates that the first frame is a HE variant frame; when a standard control field value is 10, it indicates that the first frame is an EHT variant frame; or when a standard control field value is 11, it indicates that the first frame is a scope variant frame.Alternatively, when a standard control field value is 00, it indicates that the first frame is a VHT variant frame; when a standard control field value is 01, it indicates that the first frame is a HE variant frame; when a standard control field value is 10, it indicates that the first frame is a variant frame; or when a standard control field value is 11, it indicates that the first frame is an EHT variant frame. Optionally, the third field includes a standard control field that includes bits qqrj / n / zznz / q / YiAi from a range field and an HE field in the polling dialog box field, and one or more bits in a station information field. When a value of the standard control field is 00, it indicates that the first frame is a VHT variant frame or an EHT variant frame; when a value of the standard control field is 01, it indicates that the first frame is an HE variant frame; when a value of the standard control field is 10, it indicates that the first frame is a range variant frame; or when a value of the standard control field is 11, it indicates that the first frame is invalid or reserved for future use. When the value of the standard control field is 00, it indicates that the first frame is the VHT variant frame or the EHT variant frame.Therefore, the distinction can be made based on one or more bits of the station information field. In one example, one bit of the station information field may be occupied, and the bit is used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. For example, a new disambiguation field can be set in the station information field. When a disambiguation field value is 0, it indicates that the first frame is a VHT variant frame; or when a disambiguation field value is 1, it indicates that the first frame is an EHT variant frame. Alternatively, when a disambiguation field value is 1, it indicates that the first frame is a VHT variant frame; or when a disambiguation field value is 0, it indicates that the first frame is an EHT variant frame. In another example, a bit in an association identifier field may be used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. When a bit value is 0, it indicates that the first frame is a VHT variant frame; or when a bit value is 1, it indicates that the first frame is an EHT variant frame. Alternatively, when a bit value is 1, it indicates that the first frame is a VHT variant frame; or when a bit value is 0, it indicates that the first frame is an EHT variant frame. In another example, a special association identifier value may be used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. For example, when the association identifier value is 2044, it indicates that the first frame is a VHT variant frame; or when the association identifier value is 2043, it indicates that the first frame is an EHT variant frame. With reference to the first aspect or any of the possible implementations above, in another possible implementation, the second frame includes a signal field of cqr; / n / zznz / q / YiAi Extremely high-performance EHT, a short EHT training field, and a long EHT training field. The long EHT training field includes a long training field for each antenna component. With reference to the first aspect or any of the possible implementations above, in another possible implementation, the second frame includes an extremely high-throughput EHT signal field, a short EHT training field, and a long EHT training field. The antenna portion corresponds to at least two panels, the second frame includes at least two second subframes, and the long EHT training field in the second subframe includes a long antenna training field corresponding to one of at least two antenna panels. With reference to the first aspect or any of the possible implementations above, in another possible implementation, the first frame is an NDPA Null Data Packet Advertisement frame, the second frame is an NDP Null Data Packet frame, the third frame is a Beamforming Report frame, and the fourth frame is an Activation frame. With reference to the first aspect or any of the possible implementations above, in another possible implementation, the first communication device is an access point AP, and the second communication device is a station STA. According to a second aspect, this application provides a channel scanning method. The method includes: A second communication device receiving a first frame from a first communication device, where the first frame is used to instruct the second communication device to perform channel scanning on a portion of the antennas of the first communication device. The second communication device receives a second frame sent by the first communication device, where the second frame is used by the second communication device to perform channel scanning on the portion of the antennas. The second communication device performs channel scanning on the portion of the antennas based on the second frame.The second communication device sends a third frame to the first communication device, where the third frame is used to indicate a result of the channel scanning being performed by the antennas. Optionally, the antenna portion may be a predetermined antenna that can communicate well with the second communication device, for example, it may be an antenna that is in predetermined antennas of the first communication device and that can communicate well with the second communication device. Optionally, the antenna portion may be a default antenna for communicating with the second communication device. qqrj / n / zznz / q / YiAi Accordingly, there are many ways in which the first frame indicates the front of the antennas. For example, the first frame indicates, based on one or more panel identifiers, that the second communication device perform a channel scan on an antenna corresponding to the one or more panel identifiers. In another example, the first frame indicates, based on one or more AP identifiers, that the second communication device perform a channel scan on an antenna corresponding to the one or more AP identifiers. In another example, the first frame uses an index directly indicating an antenna to indicate the antennas portion. In another example, the first frame uses an index of a start antenna and an index of an end antenna to indicate the antennas portion. In another example, the first frame uses an index of a start antenna and an index of an end antenna to indicate the antennas portion. Based on the foregoing technical solution, the first communication device may indicate to the second communication device a portion of the antennas on which the second communication device is to perform channel measurement, and the second communication device performs channel scanning only on a corresponding panel and returns the channel scanning result. This can reduce the feedback overhead of channel status information compared to performing channel scanning on all antennas of the first communication device and returning the channel scanning results each time. With reference to the second aspect, in one possible implementation, before the second communication device sends the third frame to the first communication device, the method further includes: The second communication device receives a fourth frame sent by the first communication device. The fourth frame is used to instruct the second communication device to send the third frame to the first communication device. Based on the previous technical solution, the first communication device can activate, based on the fourth frame, at least a second communication device to simultaneously feed back a third frame. This helps improve the efficiency of channel scanning. With reference to the second aspect or any of the possible implementations above, in another possible implementation, before the second communication device receives the first frame from the first communication device, the method further includes: The second communication device receives a training frame from the first communication device, where the training frame is used to perform channel sounding on all antennas of the first communication device. The second communication device sends a feedback frame to the first communication device, such that the first communication device determines the part of the antennas based on the feedback frame. Based on the previous technical solution, a set of antennas for communication with the second communication device can be predetermined based on actual channel conditions or similar. This helps increase the probability of successful subsequent communication between the first communication device and the second communication device. With reference to the second aspect or any of the possible implementations above, in another possible implementation, before the second communication device receives a training frame from the first communication device, the method further includes: The second communication device receives a pre-training frame sent by the first communication device. The pre-training frame is used to instruct the second communication device to perform a channel scan on all antennas of the first communication device. Based on the previous technical solution, the second communication device can be instructed in advance to prepare for channel scanning, so that the second communication device can prepare for channel scanning in a timely manner. This helps improve the efficiency of channel scanning. With reference to the second aspect or any of the possible implementations above, in another possible implementation, before the second communication device sends the feedback frame to the first communication device, the method further includes: The second communication device receives a wake-up frame from the first communication device. The wake-up frame is used to instruct the second communication device to send the feedback frame to the first communication device. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the first frame includes a first field. The first field is used to indicate a panel portion of the first communication device, and the antenna portion includes an antenna corresponding to the panel portion. Based on the previous technical solution, the second communication device can be instructed in advance to prepare for channel scanning, so that the second communication device can prepare for channel scanning in a timely manner. This helps improve the efficiency of channel scanning. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the first frame includes a first field. The first field is used to carry an antenna index, and the antenna index is used to indicate the antenna part. Optionally, the first frame uses an index that directly indicates an antenna to indicate the antenna part. Optionally, the first frame uses an index of a start antenna and an index of an end antenna to indicate the antenna part. Optionally, the first frame uses an index of an initial antenna and a number of antennas to indicate the antenna part. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the first frame further includes a second field. The second field is used to indicate that the first field is used to indicate a portion of the panels of the first communication device or carry an antenna index. That is, the first communication device can notify the second communication device that a current scenario is an MP MIMO scenario. In this way, communication between the first and second communication devices can adapt to different scenarios. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the first frame includes a third field. The third field is used to indicate that the first frame is a frame of an extremely high-performance EHT variant. Optionally, the third field may be one or more bits from a voiced dialog token field. For example, the third field includes a standard control field that includes bits from a scope field and a HE field in the polling dialog box field. When a standard control field value is 00, it indicates that the first frame is a VHT variant frame; when a standard control field value is 01, it indicates that the first frame is a HE variant frame; when a standard control field value is 10, it indicates that the first frame is an EHT variant frame; or when a standard control field value is 11, it indicates that the first frame is a scope variant frame.Alternatively, when a standard control field value is 00, it indicates that the NDPA frame is a VHT variant frame; when a standard control field value is 01, it indicates that the NDPA frame is a HE variant frame; when a standard control field value is 10, it indicates that the NDPA frame is a scope variant frame; or when a standard control field value is 11, it indicates that the NDPA frame is an EHT variant frame. Optionally, the third field includes a standard control field that includes bits from a range field and a HE field in the polling dialog box field, and one or more / n / zznz / q / YiAi bits in a station information field. When a value of the standard control field is 00, it indicates that the first frame is a VHT variant frame or an EHT variant frame; when a value of the standard control field is 01, it indicates that the first frame is an HE variant frame; when a value of the standard control field is 10, it indicates that the first frame is a range variant frame; or when a value of the standard control field is 11, it indicates that the first frame is invalid or reserved for future use. In the previous example, when the standard control field value is 00, it indicates that the first frame is either the VHT variant frame or the EHT variant frame. Therefore, the distinction can be made based on one or more bits in the station information field. In one example, one bit of the station information field may be occupied, and the bit is used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. For example, a new disambiguation field can be set in the station information field. When a disambiguation field value is 0, it indicates that the first frame is a VHT variant frame; or when a disambiguation field value is 1, it indicates that the first frame is an EHT variant frame. Alternatively, when a disambiguation field value is 1, it indicates that the first frame is a VHT variant frame; or when a disambiguation field value is 0, it indicates that the first frame is an EHT variant frame. In another example, a bit in an association identifier field may be used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. When a bit value is 0, it indicates that the first frame is a VHT variant frame; or when a bit value is 1, it indicates that the first frame is an EHT variant frame. Alternatively, when a bit value is 1, it indicates that the first frame is a VHT variant frame; or when a bit value is 0, it indicates that the first frame is an EHT variant frame. In another example, a special association identifier value may be used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. For example, when the association identifier value is 2044, it indicates that the first frame is a VHT variant frame; or when the association identifier value is 2043, it indicates that the first frame is an EHT variant frame. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the second frame includes a signal field of by / / n / zznz / q / Yi / u Extremely high-performance EHT, a short EHT training field, and a long EHT training field. The antenna portion corresponds to at least two antenna panels, the second frame includes at least two second subframes, and the long EHT training field in the second subframe includes a long antenna training field corresponding to one of at least two antenna panels. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the second frame includes an extremely high-performance EHT signal field, a short EHT training field, and a long EHT training field. The long EHT training field includes a long training field of each of the antenna portions. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the second frame includes an extremely high-throughput EHT signal field, a short EHT training field, and a long EHT training field. The antenna portion corresponds to at least two panels, the second frame includes at least two second subframes, and the long EHT training field in the second subframe includes a long antenna training field corresponding to one of at least two antenna panels. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the first frame is an NDPA Null Data Packet Advertisement frame, the second frame is an NDP Null Data Packet frame, the third frame is a Beamforming Report frame, and the fourth frame is an Activation frame. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the first communication device is an access point AP, and the second communication device is a station STA. According to a third aspect, this application provides a channel sounding method. The method includes: A first communication device sending a first frame to a second communication device, where the first frame is used to instruct the second communication device to perform channel sounding on a portion of the communication devices in a group of communication devices to which the first communication device belongs. The first communication device sends a second frame to the second communication device, where the second frame is used by the second communication device to perform channel sounding on the part of the communication devices.The first communication device receives a third frame from the second communication device, where the third frame is used to indicate a result of performing channel probing by the pqa / / n / zznz / q / Yi / u communication devices. The communication device group may be a multi-communication device coordination group, which is a joint transmission set including a plurality of communication devices, for example, a multi-AP coordination group. Optionally, the communication device portion may be a default communication device that can communicate well with the second communication device. Optionally, the communication device portion may be a communication device reserved for communicating with the second communication device. Accordingly, there are many ways in which the first frame indicates the front end of the antennas. For example, the first frame indicates, based on one or more panel identifiers, the second communication device to perform a channel scan on a communication device corresponding to the one or more panel identifiers. In another example, the first frame indicates, based on an identifier of one or more APs, the second communication device to perform a channel scan on the AP(s). In another example, the first frame uses an index directly indicating an antenna to indicate the front end of the communication devices. In another example, the first frame uses an index of a start antenna and an index of a end antenna to indicate the front end of the communication devices.In another example, the first frame uses an index of a start antenna and a number of antennas to indicate the part of the communication devices. Based on the foregoing technical solution, the first communication device may indicate to the second communication device a portion of the communication devices in the communication device group for which channel measurement should be performed by the second communication device. The second communication device then performs channel polling only on the corresponding communication device and returns the channel polling result. This can reduce the feedback overhead of channel status information compared to performing channel polling on all communication devices in the communication device group and feedback the channel polling results each time. With reference to the third aspect, in a possible implementation, before the first communication device receives the third frame from the second communication device, the method further includes: The first communication device sends a fourth frame to the second communication device. The fourth frame is used to instruct the second communication device to send the third frame to the first communication device. Based on the previous technical solution, the first communication device can activate, based on the fourth frame, at least a second communication device to simultaneously feed back a third frame. This helps improve the efficiency of channel scanning. With reference to the third aspect or any of the possible implementations above, in another possible implementation, before the first communication device sends the first frame to the second communication device, the method further includes: The first communication device sends a training frame to the second communication device, where the training frame is used to perform channel probing on all communication devices in the group of communication devices. The first communication device receives a feedback frame from the second communication device. The first communication device determines the part of the communication devices based on the feedback frame. Based on the previous technical solution, a communication device can be predetermined to communicate with the second communication device based on an actual channel condition or the like. This helps increase the probability of success of subsequent communication between the first communication device and the second communication device. With reference to the third aspect or any of the possible implementations above, in another possible implementation, before the first communication device sends the training frame to the second communication device, the method further includes: The first communication device sends a pre-training frame to the second communication device, where the pre-training frame is used to instruct the second communication device to perform channel scanning on all communication devices in the group of communication devices. Based on the previous technical solution, the second communication device can be instructed in advance to prepare for channel scanning, so that the second communication device can prepare for channel scanning in a timely manner. This helps improve the efficiency of channel scanning. With reference to the third aspect or any of the possible implementations above, in another possible implementation, before the first communication device receives the feedback frame from the second communication device, the method further includes: The first communication device sends a wake-up frame to the second communication device. The wake-up frame is used to instruct the second communication device to send the feedback frame to the first communication device. With reference to the third aspect or any of the possible implementations above, in another possible implementation, the first frame includes a first field. The first field is used to carry a bitmap of the communication device, and the bitmap of the communication device is used to indicate the part of the communication devices. Optionally, the first field may be used to carry the communication device bitmap, and the communication device bitmap is used to indicate the portion of the communication devices in the communication device group. For example, when the communication device group includes communication device 1 and communication device 4, the communication device bitmap may use four bits to represent the four communication devices respectively. For example, 1001 indicates that the antennas of communication device 1 and communication device 4 are antennas on which channel scanning should be performed this time. Optionally, different values ​​of the first field may be used to represent different combinations of communication devices. For example, when the communication device group includes a communication device 1 to a communication device 4, the first field includes four bits. When a value of the first field is 1111, the first field represents a communication device 1-3. When a value of the first field is 1010, the first field represents a communication device 1-2. Optionally, the first field may directly indicate a communication device index. With reference to the third aspect or any of the possible implementations above, in another possible implementation, the first frame includes a first field. The first field is used to carry an antenna index, and the antenna index is used to indicate the part of the communication devices. Optionally, the first frame uses an index that directly indicates an antenna to indicate the part of the communication devices. Optionally, the first frame uses an index of a start antenna and an index of an end antenna to indicate the part of the communication devices. Optionally, the first frame uses an index of an initial antenna and a number of antennas to indicate the part of the communication devices. With reference to the third aspect or any of the possible implementations / n / zznz / q / YiAi above, in another possible implementation, the first frame also includes a second field. The second field is used to indicate that the first field carries a bitmap of the communication device or an antenna index. In other words, the first communication device can notify the second communication device that a current scenario is a multi-device coordination scenario. In this way, communication between the first and second communication devices can adapt to different scenarios. With reference to the third aspect or any of the possible implementations above, in another possible implementation, the first frame includes a third field. The third field is used to indicate that the first frame is a frame of an extremely high-performance EHT variant. For example, the third field includes a standard control field that includes bits from a scope field and a HE field in the polling dialog box field. When a standard control field value is 00, it indicates that the first frame is a VHT variant frame; when a standard control field value is 01, it indicates that the first frame is a HE variant frame; when a standard control field value is 10, it indicates that the first frame is an EHT variant frame; or when a standard control field value is 11, it indicates that the first frame is a scope variant frame.Alternatively, when a standard control field value is 00, it indicates that the NDPA frame is a VHT variant frame; when a standard control field value is 01, it indicates that the NDPA frame is a HE variant frame; when a standard control field value is 10, it indicates that the NDPA frame is a scope variant frame; or when a standard control field value is 11, it indicates that the NDPA frame is an EHT variant frame. Optionally, the third field includes a standard control field that includes bits from a range field and a HE field in the polling dialog box field, and one or more bits in a station information field. When a value of the standard control field is 00, it indicates that the first frame is a VHT variant frame or an EHT variant frame; when a value of the standard control field is 01, it indicates that the first frame is an HE variant frame; when a value of the standard control field is 10, it indicates that the first frame is a range variant frame; or when a value of the standard control field is 11, it indicates that the first frame is invalid or reserved for future use. In the previous example, when the standard control field value is 00, it indicates that the first frame is either the VHT variant frame or the EHT variant frame. Therefore, the distinction can be made based on one or more bits in the / n / zznz / q / YiAi station information field. In one example, one bit of the station information field may be occupied, and the bit is used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. For example, a new disambiguation field can be set in the station information field. When a disambiguation field value is 0, it indicates that the first frame is a VHT variant frame; or when a disambiguation field value is 1, it indicates that the first frame is an EHT variant frame. Alternatively, when a disambiguation field value is 1, it indicates that the first frame is a VHT variant frame; or when a disambiguation field value is 0, it indicates that the first frame is an EHT variant frame. In another example, a bit in an association identifier field may be used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. When a bit value is 0, it indicates that the first frame is a VHT variant frame; or when a bit value is 1, it indicates that the first frame is an EHT variant frame. Alternatively, when a bit value is 1, it indicates that the first frame is a VHT variant frame; or when a bit value is 0, it indicates that the first frame is an EHT variant frame. In another example, a special association identifier value may be used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. For example, when the association identifier value is 2044, it indicates that the first frame is a VHT variant frame; or when the association identifier value is 2043, it indicates that the first frame is an EHT variant frame. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the second frame includes an extremely high-performance EHT signal field, a short EHT training field, and a long EHT training field. The long EHT training field includes a long training field of each of the antenna portions. With reference to the second aspect or any of the possible implementations above, in another possible implementation, the second frame includes an extremely high-throughput EHT signal field, a short EHT training field, and a long EHT training field. The antenna portion corresponds to at least two panels, the second frame includes at least two second subframes, and the long EHT training field in the second subframe includes a long antenna training field corresponding to one of at least two antenna panels. / n / zznz / q / YiAi With reference to the third aspect or any of the possible implementations above, in another possible implementation, the first frame is an NDPA Null Data Packet Advertisement frame, the second frame is an NDP Null Data Packet frame, the third frame is a Beamforming Report frame, and the fourth frame is an Activation frame. With reference to the third aspect or any of the possible implementations above, in another possible implementation, the first communication device is an access point AP, and the second communication device is a station STA. According to a fourth aspect, this application provides a channel sounding method. The method includes: A second communication device receives a first frame from a first communication device, where the first frame is used to instruct the second communication device to perform channel sounding on a portion of the communication devices in a group of communication devices to which the first communication device belongs. The second communication device receives a second frame from the first communication device, where the second frame is used by the second communication device to perform channel sounding on the portion of the communication device. The second communication device performs channel sounding on the portion of the communication device based on the second frame.The second communication device sends a third frame to the first communication device, where the third frame is used to indicate a result of the channel probing being performed by the communication devices. The communication device group may be a multi-communication device coordination group, which is a joint transmission set including a plurality of communication devices, for example, a multi-AP coordination group. Optionally, the communication device portion may be a default communication device that can communicate well with the second communication device. Optionally, the communication device portion may be a predetermined communication device for communicating with the second communication device. Accordingly, there are many ways in which the first frame indicates the front of the antennas. For example, the first frame indicates, based on one or more panel identifiers, the second communication device to perform a channel scan on a communication device corresponding to the one or more panel identifiers. In another example, the first frame indicates, based on an identifier of one or more APs, the second communication device to perform a channel scan on the qqrj / n / zznz / q / YiAi APs. In another example, the first frame uses an index directly indicating an antenna to indicate the communication device portion. In another example, the first frame uses an index of a start antenna and an index of an end antenna to indicate the communication device portion. In another example, the first frame uses an index of a start antenna and a number of antennas to indicate the communication device portion. Based on the foregoing technical solution, the first communication device may indicate to the second communication device a portion of the communication devices in the communication device group for which channel measurement should be performed by the second communication device. The second communication device then performs channel polling only on the corresponding communication device and returns the channel polling result. This can reduce the feedback overhead of channel status information compared to performing channel polling on all communication devices in the communication device group and feedback the channel polling results each time. With reference to the fourth aspect, in a possible implementation, before the second communication device sends the third frame to the first communication device, the method further includes: The second communication device receives a fourth frame sent by the first communication device. The fourth frame is used to instruct the second communication device to send the third frame to the first communication device. Based on the previous technical solution, the first communication device can activate, based on the fourth frame, at least a second communication device to simultaneously feed back a third frame. This helps improve the efficiency of channel scanning. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, before the second communication device receives the first frame from the first communication device, the method further includes: The second communication device receives a training frame from the first communication device, where the training frame is used to perform channel probing on all communication devices in the group of communication devices. The second communication device sends a feedback frame to the first communication device, such that the first communication device determines the part of the communication devices based on the feedback frame. / n / zznz / q / YiAi Based on the previous technical solution, a communication device can be predetermined to communicate with the second communication device based on an actual channel condition or the like. This helps increase the probability of success of subsequent communication between the first communication device and the second communication device. With reference to the fourth aspect or any of the previous possible implementations, in another possible implementation, before the second communication device receives the training frame from the first communication device, the method further includes: The second communication device receives a pre-training frame sent by the first communication device. The pre-training frame is used to instruct the second communication device to perform channel scanning on all communication devices in the group of communication devices. Based on the previous technical solution, the second communication device can be instructed in advance to prepare for channel scanning, so that the second communication device can prepare for channel scanning in a timely manner. This helps improve the efficiency of channel scanning. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, before the second communication device sends the feedback frame to the first communication device, the method further includes: The second communication device receives a wake-up frame from the first communication device. The wake-up frame is used to instruct the second communication device to send the feedback frame to the first communication device. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, the first frame includes a first field. The first field is used to carry a bitmap of the communication device, and the bitmap of the communication device is used to indicate the part of the communication devices. Optionally, the first field may be used to carry the communication device bitmap, and the communication device bitmap is used to indicate the portion of the communication devices in the communication device group. For example, when the communication device group includes a communication device 1 and a communication device 4, the communication device bitmap may use four bits to represent the four communication devices respectively. For example, 1001 indicates that the antennas of communication device 1 and communication device 4 are antennas on which channel scanning should be performed this time. Optionally, different values ​​of the first field may be used to represent different combinations of communication devices. For example, when the communication device group includes a communication device 1 to a communication device 4, the first field includes four bits. When a value of the first field is 1111, the first field represents a communication device 1-3. When a value of the first field is 1010, the first field represents a communication device 1-2. Optionally, the first field may directly indicate a communication device index. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, the first frame includes a first field. The first field is used to carry an antenna index, and the antenna index is used to indicate the part of the communication devices. Optionally, the first frame uses an index that directly indicates an antenna to indicate the part of the communication devices. Optionally, the first frame uses an index of a start antenna and an index of an end antenna to indicate the part of the communication devices. Optionally, the first frame uses an index of an initial antenna and a number of antennas to indicate the part of the communication devices. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, the first frame also includes a second field. The second field is used to indicate that the first field carries a bitmap of the communication device or an antenna index. In other words, the first communication device can notify the second communication device that a current scenario is a multi-device coordination scenario. In this way, communication between the first and second communication devices can adapt to different scenarios. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, the first frame includes a third field. The third field is used to indicate that the first frame is a frame of an extremely high-performance EHT variant. For example, the third field includes a standard control field that includes bits from a scope field and an HE field in the polling dialog box field. When a value of the standard control field is 00, it indicates that the first frame is a VHT variant frame; when a value of the standard control field is 01, it indicates that the first frame is a HE variant frame; when a value of the standard control field is 10, it indicates that the first frame is an EHT variant frame; or when a value of the standard control field is 11, it indicates that the first frame is a scope variant frame.Alternatively, when a standard control field value is 00, it indicates that the NDPA frame is a VHT variant frame; when a standard control field value is 01, it indicates that the NDPA frame is a HE variant frame; when a standard control field value is 10, it indicates that the NDPA frame is a scope variant frame; or when a standard control field value is 11, it indicates that the NDPA frame is an EHT variant frame. Optionally, the third field includes a standard control field that includes bits from a range field and a HE field in the polling dialog box field, and one or more bits in a station information field. When a value of the standard control field is 00, it indicates that the first frame is a VHT variant frame or an EHT variant frame; when a value of the standard control field is 01, it indicates that the first frame is an HE variant frame; when a value of the standard control field is 10, it indicates that the first frame is a range variant frame; or when a value of the standard control field is 11, it indicates that the first frame is invalid or reserved for future use. In the previous example, when the standard control field value is 00, it indicates that the first frame is either the VHT variant frame or the EHT variant frame. Therefore, the distinction can be made based on one or more bits in the station information field. In one example, one bit of the station information field may be occupied, and the bit is used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. For example, a new disambiguation field can be set in the station information field. When a disambiguation field value is 0, it indicates that the first frame is a VHT variant frame; or when a disambiguation field value is 1, it indicates that the first frame is an EHT variant frame. Alternatively, when a disambiguation field value is 1, it indicates that the first frame is a VHT variant frame; or when a disambiguation field value is 0, it indicates that the first frame is an EHT variant frame. In another example, a bit in an association identifier field may be used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. When a bit value is 0, it indicates that the first frame is a VHT variant frame; or when a bit value is 1, it indicates that the first frame is an EHT variant frame. Alternatively, when a bit value is 1, it indicates that the first frame is a VHT variant frame; or when a bit value is 0, it indicates that the first frame is an EHT variant frame. In another example, a special association identifier value may be used to further indicate whether the first frame is a VHT variant frame or an EHT variant frame. For example, when the association identifier value is 2044, it indicates that the first frame is a VHT variant frame; or when the association identifier value is 2043, it indicates that the first frame is an EHT variant frame. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, the second frame includes an extremely high performance EHT signal field, a short EHT training field, and a long EHT training field. The long EHT training field includes a long training field of each of the antenna portions. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, the second frame includes an extremely high throughput EHT signal field, a short EHT training field, and a long EHT training field. The antennas portion corresponds to at least two panels, the second frame includes at least two second subframes, and the long EHT training field in the second subframe includes a long antenna training field corresponding to one of at least two antenna panels. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, the first frame is an NDPA Null Data Packet Advertisement frame, the second frame is an NDP Null Data Packet frame, the third frame is a Beamforming Report frame, and the fourth frame is an Activation frame. With reference to the fourth aspect or any of the possible implementations above, in another possible implementation, the first communication device is an access point AP, and the second communication device is a station STA. According to a fifth aspect, this application provides a channel sounding apparatus. The apparatus is configured to perform the method provided in the first aspect. Specifically, the apparatus may include modules configured to perform the first aspect and any of the possible implementations of the first aspect. According to a sixth aspect, this application provides a channel sounding apparatus. The apparatus is configured to perform the method provided in the second aspect. qqrj / n / zznz / q / YiAi Specifically, the apparatus may include modules configured to perform the second aspect and any of the possible implementations of the second aspect. According to a seventh aspect, this application provides a channel sounding apparatus. The apparatus is configured to perform the method contemplated in the first aspect. Specifically, the apparatus may include modules configured to perform the third aspect and any of the possible implementations of the third aspect. According to an eighth aspect, this application provides a channel sounding apparatus. The apparatus is configured to perform the method provided in the second aspect. Specifically, the apparatus may include modules configured to perform the fourth aspect and any of the possible implementations of the fourth aspect. According to a ninth aspect, this application provides a channel probing apparatus, including a processor. The processor is coupled to a memory and may be configured to execute instructions in the memory, to implement the method according to the first aspect and any of the possible implementations of the first aspect. Optionally, the apparatus further includes a memory. Optionally, the apparatus further includes a communication interface, and the processor is coupled to the communication interface. In one implementation, the device is an access point. When the device is an access point, the communication interface may be a transceiver or an input / output interface. In another implementation, the device is a chip configured in an access point. When the device is a chip configured in an access point, the communication interface may be an input / output interface. In one implementation, the device is a station. When the device is a station, the communication interface may be a transceiver or an input / output interface. In another implementation, the device is a chip configured in a station. When the device is a chip configured in a station, the communication interface may be an input / output interface. In another implementation, the device is a chip or a system of chips. Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit. According to a tenth aspect, this application provides a channel probing apparatus, including a processor. The processor is coupled to a memory, and may be configured to execute instructions in the memory, to implement the method according to the second aspect and any of the possible implementations of the second aspect. Optionally, the apparatus further includes a memory. Optionally, the apparatus further includes a communication interface, and the processor is coupled to the communication interface. In one implementation, the device is an access point. When the device is an access point, the communication interface may be a transceiver or an input / output interface. In another implementation, the device is a chip configured in an access point. When the device is a chip configured in an access point, the communication interface may be an input / output interface. In one implementation, the device is a station. When the device is a station, the communication interface may be a transceiver or an input / output interface. In another implementation, the device is a chip configured in a station. When the device is a chip configured in a station, the communication interface may be an input / output interface. In another implementation, the device is a chip or a system of chips. Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit. According to an eleventh aspect, this application provides a channel probing apparatus, including a processor. The processor is coupled to a memory and may be configured to execute instructions in the memory, to implement the method according to the third aspect and any of the possible implementations of the third aspect. Optionally, the apparatus further includes a memory. Optionally, the apparatus further includes a communication interface, and the processor is coupled to the communication interface. In one implementation, the device is an access point. When the device is an access point, the communication interface may be a transceiver or an input / output interface. In another implementation, the device is a chip configured in an access point. When the device is a chip configured in an access point, the communication interface may be an input / output interface. In one implementation, the device is a station. When the device is a station, the communication interface may be a transceiver or an input / output interface. In another implementation, the device is a chip configured in a station. When the device is a chip configured in a station, the communication interface may be an / n / zznz / q / YiAi input / output interface. In another implementation, the device is a chip or a system of chips. Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit. According to a twelfth aspect, this application provides a channel probing apparatus, including a processor. The processor is coupled to a memory and may be configured to execute instructions in the memory, to implement the method according to the fourth aspect and any of the possible implementations of the fourth aspect. Optionally, the apparatus further includes a memory. Optionally, the apparatus further includes a communication interface, and the processor is coupled to the communication interface. In one implementation, the device is an access point. When the device is an access point, the communication interface may be a transceiver or an input / output interface. In another implementation, the device is a chip configured in an access point. When the device is a chip configured in an access point, the communication interface may be an input / output interface. In one implementation, the device is a station. When the device is a station, the communication interface may be a transceiver or an input / output interface. In another implementation, the device is a chip configured in a station. When the device is a chip configured in a station, the communication interface may be an input / output interface. In another implementation, the device is a chip or a system of chips. Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit. According to a thirteenth aspect, this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by an apparatus, the apparatus is enabled to implement the method according to the first aspect and any of the possible implementations of the first aspect. According to a fourteenth aspect, this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by an apparatus, the apparatus is enabled to implement the method according to the second aspect and any of the possible implementations of the second aspect. cqa; / n / zznz / q / YiAi According to a fifteenth aspect, this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by an apparatus, the apparatus is enabled to implement the method according to the third aspect and any of the possible implementations of the third aspect. According to a sixteenth aspect, this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by an apparatus, the apparatus is enabled to implement the method according to the fourth aspect and any of the possible implementations of the fourth aspect. According to a seventeenth aspect, this application provides a computer program product including instructions. When the instructions are executed by a computer, an apparatus is enabled to implement the method according to the first aspect and any of the possible implementations of the first aspect. According to an eighteenth aspect, this embodiment provides a computer program product including instructions. When the instructions are executed by a computer, an apparatus is enabled to implement the method according to the second aspect and any possible implementations of the second aspect. According to a nineteenth aspect, this application provides a computer program product including instructions. When the instructions are executed by a computer, an apparatus is enabled to implement the method according to the third aspect and any of the possible implementations of the third aspect. According to a twentieth aspect, this embodiment provides a computer program product including instructions. When the instructions are executed by a computer, an apparatus is enabled to implement the method according to the fourth aspect and any of the possible implementations of the fourth aspect. According to a twenty-first aspect, this application provides a chip. The chip includes a processor and a communication interface, the processor and the interface circuit are coupled to each other, the communication interface is configured to communicate with another device, and the processor is configured to implement the method according to the first aspect or any implementation of the first aspect, the method according to the second aspect or any implementation of the second aspect, the method according to the third aspect or any implementation of the third aspect, or the method according to the fourth aspect or any implementation of the fourth aspect. In one possible implementation, the chip further includes a memory, configured / n / zznz / q / YiAi to store instructions executed by the processor, store input data required by the processor to execute instructions, or store data generated after the processor executes instructions. According to a twenty-second aspect, this application provides a communication system, which includes the above access point and station. BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic diagram of a wireless communication system architecture applicable to an embodiment of this application; FIGURE 2 is a diagram of an internal structure of an AP according to an embodiment of this application; FIGURE 3 is a diagram of an internal structure of a STA according to an embodiment of this application; FIGURE 4 is a schematic diagram of single-user channel state information feedback in IEEE 802.11ax; FIGURE 5 is a schematic diagram of multi-user channel state information feedback in IEEE 802.11ax; FIGURE 6 is a schematic diagram of user channel state information feedback applicable to D-MIMO; FIGURE 7 shows a frame structure of an NDPA frame; FIGURE 8 shows a frame structure of an NDP frame; FIGURE 9 shows the structure of an activation frame; FIGURE 10 shows a frame structure of a beamforming report frame; FIGURE 11 is a schematic flow diagram of a channel sounding method according to one embodiment of this application; FIGURE 12 shows an example of application of a channel probing method according to an embodiment of this application; FIGURE 13 shows the structure of a frame of an NDPA according to an embodiment of this application; FIGURE 14 is a schematic diagram of an implementation of a station information field in an NDPA frame according to an embodiment of this application; FIGURE 15 is a schematic diagram of the structure of a protection device according to an embodiment of this application; FIGURE 16 is a schematic diagram of another implementation of an NDP frame in accordance with an embodiment of this application; / n / zznz / q / YiAi FIGURE 17 is a schematic diagram of another implementation of an NDP frame in accordance with an embodiment of this application; FIGURE 18 is a schematic diagram of a panel pre-training procedure according to one embodiment of this application; FIGURE 19 is a schematic diagram of an implementation of a training frame according to one embodiment of this application; FIGURE 20 shows a frame structure of a panel training activation frame according to an embodiment of this application; FIGURE 21 shows the structure of a feedback frame according to one embodiment of this application; FIGURE 22 is a schematic diagram of an OFDMA-based panel pre-training procedure according to an embodiment of this application; FIGURE 23 is a schematic diagram of a MIMO-based panel pre-training procedure in accordance with one embodiment of this application; FIGURE 24 shows another frame structure of a feedback frame according to an embodiment of this application; FIGURE 25 is a schematic diagram of the structure of a channel sounding apparatus according to an embodiment of this application; and FIGURE 26 is a schematic diagram of another structure of a channel sounding apparatus according to an embodiment of this application. DETAILED DESCRIPTION OF THE INVENTION The technical solutions of this application are described below with reference to the attached drawings. The technical solutions of the embodiments of the present application may be applied to various communication systems, such as a wireless local area network (WLAN) communication system, a global system of mobile communication (GSM), a code division multiple access (CDMA) system, a wideband code division multiple access (WCDMA) system, a general packet radio service (GPRS), a long term evolution (LTE) system, a frequency division duplex (FDD) LTE system, a time division duplex (TDD) LTE system, a universal mobile telecommunication system (UMTS),a worldwide interoperability for microwave access (WiMAX) communication system and a fifth generation (5G) or new radio ( / n / zznz / q / YiAi, NR). The following is used as an example for the description. Only a WLAN system is used below as an example to describe an application scenario in the embodiments of this application and a method in the embodiments of this application. Specifically, the embodiments of this application may be applicable to a wireless local area network (WLAN), and the embodiments of this application may be applicable to any protocol in the IEEE 802.11 protocol suite currently used in a WLAN. The WLAN may include one or more basic service sets (BSS), and the network nodes in the basic service set include an AP and a STA. Specifically, in embodiments of this application, an initiating device and a responding device may be user stations (STAs) in the WLAN. The user station may also be referred to as a system, subscriber unit, access terminal, mobile station, mobile, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, user apparatus, or user equipment (UE). The STA may be a cellular telephone, a cordless telephone, a session initiation protocol (SIP) telephone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless local area network (WLAN) communication capability, a portable device, a computing device, or other processing device connected to a wireless modem. Additionally, the initiating device and the responding device in the embodiments of this request may alternatively be APs in the WLAN. The AP may be configured to: communicate with an access terminal via a wireless local area network, and transmit data from the access terminal to one side of the network, or transmit data from the network side to the access terminal. To facilitate understanding of the embodiments of this application, the communication system shown in FIG. 1 is first used as an example to describe in detail a communication system to which the embodiments of this application are applicable. The communication system shown in FIG. 1 may be a WLAN system. The WLAN system of FIG. 1 may include one or more APs and one or more STAs. In FIG. 1, an AP (e.g., an AP 1 in FIG. 1) and two STAs (e.g., a STA 1 and a STA 2 in FIG. 1) are used as an example. Antennas of the AP are mounted on a plurality of panels (e.g., a panel 1 and a panel 2). Each panel includes an antenna portion. The plurality of panels may be connected to each other in wired mode, or may perform data transmission in wireless mode.Each STA may be served by a single pqa / / n / zznz / q / Yi / u panel and a panel antenna resource, or may be served by a plurality of panels and panels' antenna resources together. Wireless communication can be implemented between the AP and the STA according to various standards. For example, wireless communication between the AP and the STA can be implemented using single-user multiple-input multiple-output (SU-MIMO) technology or multi-user multiple-input multiple-output (MU-MIMO) technology. An access point is also known as a wireless access point, hotspot, or the like. An AP is an access point for a mobile user to access a wired network, and is primarily deployed in homes, buildings, and campuses, or outdoors. An AP is a bridge that connects a wired network and a wireless network. The main function of an AP is to connect wireless network clients to each other and then connect the wireless network to the Ethernet. Specifically, an access point can be a communication server, a router, a switch, a bridge, a computer, a mobile phone, or the like with a wireless fidelity (Wi-Fi) chip. Optionally, an AP can be a device that supports multiple WLAN standards, such as 802.11. FIG. 2 is a diagram of the internal structure of an AP product.In FIG. 2, the AP includes a physical layer (PHY) processing circuit, a media access control (MAC) processing circuit, a memory, a controller, a scheduler, and a processor. The physical layer processing circuit may be configured to process a physical layer signal. The MAC layer processing circuit may be configured to process a MAC layer signal. The memory may be configured to store signaling information, a pre-agreed preset value, and the like. The controller is a component for controlling. The scheduler is a component for scheduling. The processor may be configured to analyze the signaling information, process related data, and the like. A STA product is typically a terminal product, for example, a mobile phone or a laptop computer, that supports the 802.11 series standards. FIG. 3 is a structural diagram of a STA with a single antenna. In an actual scenario, the STA may alternatively have multiple antennas, and may be a device with more than two antennas. In FIG. 3, the STA may include a physical layer processing circuit and a media access control processing circuit. The physical layer processing circuit may be configured to process a physical layer signal. The MAC layer processing circuit may be configured to process a MAC layer signal. The memory may be configured to store signaling information, a pre-agreed preset value, and the like. The controller is a component for controlling. The scheduler is a component for programming.The processor may be configured to analyze the signaling information, process related data, and the like. It should be noted that this embodiment of this application is also applicable to a scenario in which there are a plurality of APs and a plurality of STAs, a plurality of APs and a plurality of APs, or a plurality of STAs and a plurality of STAs. The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard discusses a next-generation Extremely High Throughput (EHT) working group for IEEE 802.11ax, and considers the introduction of higher bandwidth (e.g., 320 MHz) and more streams (e.g., 16 spatial streams) in a next-generation wireless local area network (WLAN). For EHT, throughput is to be improved by increasing the number of spatial streams. However, due to a limitation in the capacity of a wireless device, a single access point (AP) can barely provide 16 spatial streams. To solve the above problems, a multi-panel multiple input multiple output (MP MIMO) technology has emerged. MP MIMO means that a wireless device (e.g., a base station in a cellular network, an AP in a WLAN, or a terminal device) is formed by interconnecting a plurality of panels. A plurality of transceiver antennas are mounted on each panel. That is, the antenna resources of a wireless device are dispersed across a plurality of panels that are close or far from each other. MP MIMO can reduce the deployment costs and complexity of numerous antennas and improve scalability, network coverage capacity, and MIMO channel gain. MP MIMO provides a viable solution for utilizing more streams or antenna resources for a next-generation WLAN. However, regardless of whether the antenna resources are centralized or located on a plurality of panels, a technical requirement for using MIMO technology in a WLAN is a channel scanning process. That is, the AP can serve one or more stations (station, STA) in a MIMO manner through a plurality of antennas only after a non-AP station (non-AP STA) completes channel scanning with the AP and returns a channel scanning result. FIGURE 4 is a schematic diagram of single-user channel state information feedback in IEEE 802.11ax. A channel state information feedback procedure shown in FIGURE 4 is a non-trigger based (Non-TB) channel probing procedure, and is typically used in pqa / / n / zznz / q / Yi / u, a channel probing procedure between an AP and a single STA. For example, the AP is a channel probing initiator. The AP first sends a Nuil Data Packet Announcement (NDPA) frame to notify which STA needs to perform channel probing, and notifies the channel probing-related parameters to the STAs that need to perform channel probing.Next, after a short interframe space (SIFS), the AP sends a null data packet (NDP) frame, where the NDP frame has no data field part and does not carry a MAC frame. The STA performs channel estimation using NDP, and then returns, based on a beamforming report (BF Report) frame, a channel estimation result, for example, channel state information (CSI) or channel quality information (CQI). FIG. 5 is a schematic diagram of multi-user channel state information feedback in IEEE 802.11ax. Based on FIG. 4, a trigger-based multi-user channel state information feedback mechanism is introduced into the channel state information feedback method shown in FIG. 5. Specifically, the AP sends a trigger frame (TF) on a SIFS after an NDP frame is sent, to trigger a plurality of STAs (e.g., STA 1, STA 2, and STA 3) to simultaneously feedback a beamforming report. In this way, the channel probing efficiency can be further improved. FIG. 6 is a schematic diagram of channel state information feedback applicable to distributed multiple input multiple output (D-MIMO). Assume that there are a primary AP (primary AP ) and one or more secondary APs (secondary AP ) among a plurality of APs participating in D-MIMO transmission. The primary AP first sends a slave trigger frame to the secondary AP. After receiving the slave trigger frame, the secondary AP estimates a carrier frequency offset (CFG) and the like. The primary AP and the secondary AP then simultaneously send an NDPA to a STA to instruct it to prepare for channel scanning. The primary AP then sends a slave trigger frame again to the secondary AP.After receiving the secondary wake-up frame, the secondary AP again estimates a CFG and the like and estimates a reference channel, so that the secondary AP performs pre-correction before the secondary AP sends an NDP, to synchronize with the primary AP. Finally, the primary AP and the secondary AP send an NDP packet to the STA simultaneously. The STA is not shown in FIG. 6. After receiving the NDPAs, the STA knows that it will participate in channel scanning. After receiving the NDPs, the STA knows that it will participate in channel scanning. Similar to the procedures in FIG. 4 and FIG. 5, in a subsequent procedure, the STA returns a beamforming report to each of the primary APs and the secondary APs. The NDPA frame, NDP frame, activation frame, and beamforming report frame of FIGURE 4 to FIGURE 6 may be shown in FIGURE 7, FIGURE 8, FIGURE 9, and FIGURE 10, respectively. Figure 7 shows a frame structure of an NDPA frame. The frame structure shown in Figure 7 is a frame structure of an NDPA in IEEE 802.11ax. The NDPA frame in IEEE 802.11ax is also called a high-efficiency (HE) NDPA frame. The NDPA frame inherits a type and subtype from a very high throughput (VHT) NDPA frame, and uses a reserved bit in a sounding dialog token field to distinguish between VHT NDPA and HE NDPA. Compared with VHT NDPA, the station information field in the HE NDPA frame is extended to four bytes, and partial bandwidth information (Partial BW Info) is introduced to indicate a resource used by the STA to feedback channel state information. A resource unit (RU) start index to an RU end index may indicate a segment of contiguous RUs.Additionally, a grouping number (Ng) is used to indicate which Ng subcarriers are grouped into a group. The entire subcarrier group only needs to provide feedback of channel state information, thereby reducing feedback compression. The codebook size is used to indicate the quantization precision. Different precisions correspond to different overheads. FIGURE 8 shows a frame structure of an NDP frame. As shown in FIGURE 8, the NDP frame includes a non-high-throughput short training field (L-STF), a non-high-throughput long training field (LLTF), a non-high-throughput signal field (LSIG), an extremely high-throughput short training field (EHT-STF), an extremely high-throughput long training field (EHT-LTF), an extremely high-throughput signal field (EHT-SIG), and a packet extension field. FIG. 9 shows the structure of a trigger frame. The frame structure shown in FIG. 9 is an trigger frame of a beamforming report query variant (BFRP). The trigger frame is one of a plurality of trigger frame variants, and is used to trigger a plurality of STAs to simultaneously feedback a beamforming report. As shown in (a) in FIG. 9, a frame format of the trigger frame includes a common field and a user information list, and (b) in FIG. 9 shows the content included in a piece of user information in the user information list. FIGURE 10 shows a frame structure of a beamforming report frame. A frame carrying channel state information in IEEE 802.11ax is referred to as a High Efficiency Compressed Beamforming and Channel State Information Report (HE) frame, which includes an HE MIMO control field and a beamforming report field. FIGURE 10 shows an HE MIMO control field. In some embodiments, in addition to feedback CSI, the High Efficiency Compressed Beamforming and Channel State Information Report frame in IEEE 802.11ax may also feedback CQI, including only a signal-to-noise ratio. It should be noted that, in this implementation, CSI and CQI are not specifically distinguished below, and are collectively referred to as CSI. From the above, it can be seen that more channel state feedback information is required if higher bandwidth and more spatial streams are introduced. This results in higher feedback overheads. Therefore, how to reduce channel state information overload becomes an urgent problem to be solved. To solve the above problem, this application provides a channel probing method and apparatus, to reduce the overhead of feedback of channel state information. The technical solutions provided in this application are described in detail below with reference to the accompanying drawings. The embodiments of this application may be applied to a variety of different scenarios, for example, a scenario (specifically, an MP-MIMO scenario) shown in FIG. 1 , a multi-communication device coordination scenario, a scenario in which a plurality of APs communicate with a plurality of STAs, a scenario in which a plurality of APs communicate with a plurality of APs, and a scenario in which a plurality of STAs communicate with a plurality of STAs. Two parties performing communication may differ in different scenarios. For example, in the scenario shown in FIG. 1 , the two parties performing communication are an AP and a STA.In another example, in a scenario where a plurality of APs communicate with a plurality of APs, the two parties performing the communication are both APs. In another example, in a scenario where a plurality of STAs communicate with a plurality of STAs, the two parties performing the communication are both STAs. For ease of description, in embodiments of this application, the two parties performing the communication are referred to as a first communication device and a second communication device. The first communication device may correspond to the above initiating device or responding device, and the second communication device may correspond to the above responding device or initiating device. In an MP-MIMO scenario, FIGURE 11 is a schematic flow diagram of a channel probing method according to one embodiment of this application. The method shown in FIGURE 11 may include the following steps. At 1110, a first communication device sends a first frame to a second communication device, and the second communication device receives the first frame from the first communication device accordingly. The first frame is used to instruct the second communication device to perform a channel scan on a portion of the antennas of the first communication device. Optionally, the antenna portion may be a predetermined antenna that can communicate well with the second communication device, for example, it may be an antenna that is in predetermined antennas of the first communication device and that can communicate well with the second communication device. Optionally, the antenna portion may be an antenna, in the antennas of the first communication device, predetermined for communication with the second communication device. Optionally, the first frame may be an enhanced NDPA frame. The enhanced NDPA frame is described in detail below. Optionally, the first frame may be a newly introduced control frame that is used to indicate an antenna array on which the second communication device should perform channel scanning. At 1120, the first communication device sends a second frame to the second communication device, and the second communication device receives the second frame from the first communication device accordingly. The second frame is used by the second communication device to perform channel scanning by the antennas. Optionally, the first communication device may send the second frame to the second communication device a first preset period of time after sending the first frame. The first preset period of time may be of any duration, for example, it may be one or more SIFSs. / n / zznz / q / YiAi Optionally, the second frame may be an enhanced NDP frame. The enhanced NDP frame is described in detail below. In step 1130, the second communication device, based on the received second frame, performs a channel scan on the antenna portion indicated in the first frame. Channel scanning may also be referred to as channel estimation, and the two are collectively referred to as channel scanning in the embodiments of this application. Optionally, 1140 may be performed after 1130. For example, when the first communication device instructs a plurality of second communication devices to perform channel scanning, 1140 may further be performed after 1130. At 1140, the first communication device sends a fourth frame to the second communication device, and the second communication device receives the fourth frame from the first communication device accordingly. The fourth frame is used to instruct the second communication device to return the result of the channel scanning. Optionally, the first communication device may send the fourth frame to the second communication device a second preset period of time after sending the second frame. The second preset period of time may be of any duration; for example, it may be one or more SIFSs. Optionally, the fourth frame may be the activation frame shown in FIGURE 9. Optionally, the fourth frame may be an enhanced wake-up frame. In addition to the functions of the wake-up frame shown in FIG. 9, the enhanced wake-up frame may further instruct the second communication device to report a channel scan result corresponding to an antenna of the second communication device. At 1150, the second communication device sends a third frame to the first communication device, and the first communication device receives the third frame from the second communication device accordingly. The third frame is used to indicate the result of the channel scan of the antenna portion. Optionally, after receiving the second frame, the second communication device sends the third frame to the first communication device after a third preset period of time. The third preset period of time can be of any length; for example, it can be one or more SIFSs. Optionally, after receiving the fourth frame, the second communication device sends the third frame to the first communication device. The above method is also applicable to a coordination scenario of multiple / n / zznz / q / YiAi communication devices, a first frame is used to instruct the second communication device to perform channel scanning on a portion of the communication devices in a communication device group to which the first communication device belongs, a second frame is used by the second communication device to perform channel scanning on the portion of the communication devices, and a third frame is used to indicate a result of performing channel scanning on the portion of the communication devices. The method shown in FIGURE 11 is described below with reference to specific examples. Example 1 In an MP MIMO scenario, FIG. 12 shows an exemplary application of a channel probing method according to an embodiment of this application. In FIG. 12, an AP may correspond to the first previous communication device, a STA 1 and a STA 2 may correspond to the second previous communication device, an enhanced NDPA corresponds to the first previous frame, an enhanced NDP frame corresponds to the second previous frame, a BFRP frame corresponds to the fourth previous frame, and a beamforming report corresponds to the third previous frame. The AP may send the enhanced NDPA frame, the enhanced NDP frame, and the BFRP frame on all or part of the frames. Specifically, the AP first sends the enhanced NDPA frame on panel 1 and panel 3 jointly. The enhanced NDPA frame instructs STA 1 to measure panel 1 and panel 2, and instructs STA 2 to measure panel 3 and panel 4. Then, after a SIFS, all panels of the AP jointly send the enhanced NDP frame. Additionally, after receiving the enhanced NDPA frame, STA 1 detects the enhanced NDP frame, and performs channel scanning only on panel 1 and panel 2. After receiving the enhanced NDPA frame, STA 2 detects the enhanced NDP frame and performs channel scanning only on panel 3 and panel 4. Then, after a SIFS, the AP sends the BFRP frame on panel 1 and panel 3 jointly, to cause STA 1 and STA 2 to report a beamforming report.Finally, after a SIFS, STA 1 and STA 2 respectively feed back beamforming reports on the resources allocated to STA 1 and STA 2. A beamforming report from STA 1 is used to feed back the channel sounding results of panel 1 and panel 2. A beamforming report from STA 2 is used to feed back the channel sounding results of panel 3 and panel 4. qqr; / n / zznz / q / YiAi Example 2 In a multi-communication device coordination scenario, a multi-communication device coordination group is a joint transmission set that includes a plurality of communication devices, and may send the enhanced NDPA frame, the enhanced NDP frame, and the BFRP frame using all or a portion of the plurality of communication devices. A communication device that sends the enhanced NDPA frame may correspond to the previous first communication device, a communication device that receives the enhanced NDPA frame may correspond to the previous second communication device, the enhanced NDPA frame corresponds to the previous first frame, the enhanced NDP frame corresponds to the previous second frame, the BFRP frame corresponds to the previous fourth frame, and the beamforming report corresponds to the previous third frame. For example, the first communication device is an AP, and the second communication device is a STA. Specifically, first, some or all of the APs in a multi-AP coordination group send the above Enhanced NDPA frame. The Enhanced NDPA frame indicates a subset of APs to be measured by each non-AP STA. The AP subset may include a primary AP and a secondary AP. The AP subsets corresponding to all non-AP STAs may be the same or different. In this case, the antenna set includes the antennas included in the AP subset. Then, after sending the Enhanced NDPA frame and after a SIFS, all APs in the multi-AP coordination group jointly send the Enhanced NDP frame.Next, if any non-AP STA receives the NDPA frame, determines that this time the STA is requested to perform a channel probing procedure, and immediately receives the Enhanced NDP frame, the non-AP STA measures a channel of a corresponding subset of APs. Then, after sending the Enhanced NDP frame and following a SIFS, some or all of the APs in the multi-AP coordination group send a BFRP activation frame. Finally, after receiving the BFRP activation frame, the non-AP STA reports only a beamforming report of a corresponding subset of APs on a resource assigned to the non-AP STA. Based on the above technical solutions, the first communication device may instruct the second communication device to perform channel scanning on a portion of the antennas of the first communication device, or to perform channel scanning on a portion of the communication devices in a group of communication devices to which the first communication device belongs.When the first communication device knows in advance which antennas of the first communication device are used to communicate with the second communication device, or the first communication device knows in advance which antennas of the communication devices in the coordination group to which the first communication device belongs are used to communicate with the second communication device, the first communication device may instruct the second communication device to perform channel scanning only on a corresponding antenna or communication device, and return the channel scanning result. This may reduce channel state information overload. The enhanced NDPA frame and enhanced NDP frame in this embodiment of this application are described below. The enhanced NDPA frame in this embodiment of this application may take many forms, as long as the functions of the first frame can be implemented. In an MP MIMO scenario, in some embodiments, the enhanced NDPA frame includes a first field. The first field is used to indicate an antenna of the first communication device on which channel scanning is to be performed by the second communication device. In one example, the first field is used to carry a panel bitmap, and the panel bitmap is used to indicate a portion of the panels of the first communication device. Thus, the antenna on which channel scanning is to be performed by the second communication device includes an antenna corresponding to the portion of the panels. In another example, the first field is used to carry an antenna index, and the antenna index indicates an antenna on which channel scanning is to be performed by the second communication device. For example, the antenna index includes an antenna quantity and an index of a starting antenna.In another example, the antenna index includes an index of a start antenna and an index of a end antenna. In another example, the antenna index includes an index of each antenna on which the second communication device is to perform channel scanning. Optionally, the enhanced NDPA frame also includes a second field. The second field is used to indicate that the first field contains the bitmap of the previous panel or the previous antenna index. Optionally, the Enhanced NDPA frame includes a third field. The third field is used to indicate that the first frame is an EHT variant frame. In a multi-communication device coordination scenario, in some embodiments, the enhanced NDPA frame includes a first field. The first field is used to indicate a communication device that is in the group of communication devices and for which channel scanning is to be performed by the second communication device. In one example, the first field is used to carry a bitmap of the communication device. In another example, the first field is used to carry an antenna index / n / zznz / q / YiAi. The antenna index may correspond to a corresponding communication device. Thus, the antenna index may be used to indicate a communication device that is in the group of communication devices and for which channel scanning is to be performed by the second communication device. For example, the antenna index includes an antenna quantity and an index of a starting antenna.In another example, the antenna index includes an index of a start antenna and an index of a end antenna. In another example, the antenna index includes an index of each antenna on which the second communication device is to perform channel scanning. Optionally, the enhanced NDPA frame also includes a second field. The second field is used to indicate that the first field contains the bitmap of the previous communication device or the previous antenna index. Optionally, the Enhanced NDPA frame includes a third field. The third field is used to indicate that the first frame is an EHT variant frame. An enhanced NDPA frame is described below with reference to a specific example. FIG. 13 shows a frame structure of an NDPA frame according to an embodiment of this application. As shown in FIG. 13, the NDPA frame may include a frame control field (frame control), a duration field (duration), a receiver address (RA) field, a transmitter address (TA) field, a sounding dialog token field, a station information (STA Info) field, a frame check sequence (FCS) field, and the like. The frame control field, the duration field, the receiver address field, the transmitter address field, and the frame check sequence field may be consistent with those of the current IEEE 802.11.This request focuses on improving the polling dialog field and the station information field. First, an Enhanced NDPA frame may indicate a type of NDPA, for example, an EHT NDPA frame, a VHT NDPA frame, a HE NDPA frame, or a Ranging NDPA frame. In some possible implementations, the roles of the bits in the scope field and the HE field in the IEEE 802.11 polling handshake token field are redefined in this embodiment of this application to indicate the type of NDPA frame on a bit-by-bit basis. Before redefining the roles, when the values ​​of the scope field and the HE field are 10, it indicates that the NDPA frame is a scope NDPA frame; or when the values ​​of the scope field and the HE field are 01, it indicates that the NDPA frame is an HE NDPA frame. After redefining the roles, the roles of the bits in the scope field and the HE field are changed to those of a standard control field (standard / n / zznz / q / YiAi control). For example, as shown in FIGURE 13, the first and second bits of the IEEE 802.11 polling handshake field are redefined in this application. There are many implementations of the standard control field in this form of this application. Implementation 1 As shown in Table 1, the standard control field includes two bits. When a value of the standard control field is 00, it indicates that the NDPA frame is a VHT NDPA frame or an EHT NDPA frame. In this case, the VHT NDPA frame and the EHT NDPA frame must be further distinguished based on an enhanced station information field. In this case, after receiving the NDPA frame, the second communication device must further obtain a value of a related bit in at least one station information field upon learning that the value of the standard control field is 00, in order to determine a specific type of the NDPA frame. In one example, a bit in the station information field may be occupied, and the bit is used to further indicate whether the NDPA frame is a VHT NDPA frame or an EHT NDPA frame. For example, a new disambiguation field can be set in the station information field.When a value of the disambiguation field is 0, it indicates that the NDPA frame is a VHT NDPA frame; or when a value of the disambiguation field is 1, it indicates that the NDPA frame is an EHT NDPA frame. Alternatively, when a value of the disambiguation field is 1, it indicates that the NDPA frame is a VHT NDPA frame; or when a value of the disambiguation field is 0, it indicates that the NDPA frame is an EHT NDPA frame. In another example, a bit in an association identifier field may be used to further indicate whether the NDPA frame is a VHT NDPA frame or an EHT NDPA frame. When a value of the bit is 0, it indicates that the NDPA frame is a VHT NDPA frame; or when a value of the bit is 1, it indicates that the NDPA frame is an EHT NDPA frame. Alternatively, when a bit value is 1, it indicates that the NDPA frame is a VHT NDPA frame; or when a bit value is 0, it indicates that the NDPA frame is an EHT NDPA frame.In another example, a special association identifier value may be used to further indicate whether the NDPA frame is a VHT NDPA frame or an EHT NDPA frame. For example, when the association identifier value is 2044, it indicates that the NDPA frame is a VHT NDPA frame; or when the association identifier value is 2043, it indicates that the NDPA frame is an EHT NDPA frame. When the standard control field value is 01, it indicates that the NDPA frame is an HE NDPA frame. In this case, the meaning of the standard control field is compatible and consistent with that of IEEE 802.11ax. qqrj / n / zznz / q / YiAi When the standard control field value is 10, it indicates that the NDPA frame is a scoped NDPA frame. In this case, the meaning of the standard control field is compatible and consistent with that of IEEE 802.11az. When a standard control field value is 11, it indicates that the NDPA frame is invalid or reserved for future use. / n / zznz / q / YiAi Table 1: Implementation 1 of a standard control field Value of a standard control field Meaning 0 0 VHT NDPA or EHT NDPA 0 1 HE NDPA 1 0 Scope NDPA 1 1 Invalid or reserved Implementation 2 As shown in Table 2, the standard control field includes two bits. When a value of the standard control field is 00, it indicates that the NDPA frame is a VHT NDPA frame. When a value of the standard control field is 01, it indicates that the NDPA frame is an HE NDPA frame. In this case, the meaning of the standard control field is compatible and consistent with that of IEEE 802.11ax. When a value of the standard control field is 10, it indicates that the NDPA frame is an EHT NDPA frame. When a value of the standard control field is 11, it indicates that the NDPA frame is a scope NDPA frame. Table 2: Implementation 2 of a standard control field Value of a standard control field Meaning 0 0 VHT NDPA 0 1 HE NDPA 1 0 EHT NDPA 1 1 Scope NDPA It should be understood that Implementation 1 and Implementation 2 of the standard control field are merely examples, and that there are many other possible implementations of the standard control field. For example, when a value of the standard control field is 00, it indicates that the NDPA frame is a VHT NDPA frame. When a value of the standard control field is 01, it indicates that the NDPA frame is an HE NDPA frame. In this case, the meaning of the standard control field is compatible and consistent with that of IEEE 802.11ax. When a standard control field value is 10, it indicates that the NDPA frame is a scope NDPA frame. When a standard control field value is 11, it indicates that the NDPA frame is an EHT NDPA frame. For another example, when a standard control field value is 00, it indicates that the NDPA frame is an EHT NDPA frame. When a standard control field value is 01, it indicates that the NDPA frame is an HE NDPA frame. In this case, the meaning of the standard control field is compatible and consistent with that of IEEE 802.11ax. When a standard control field value is 10, it indicates that the NDPA frame is a scope NDPA frame. When a standard control field value is 11, it indicates that the NDPA frame is a VHT NDPA frame. This method can avoid station confusion when the size of an EHT station information field is enlarged. 2. Improved station information field In this embodiment of the request, the length of the station information field is extended from four to six bytes. The station information field has many implementation forms, provided that the station information field can directly or indirectly indicate an antenna array on which channel scanning is to be performed by the second communication device. This is not specifically limited to this embodiment of this request. FIGURE 14 shows four implementations of the station information field. Implementation 1 In an MP MIMO scenario, the functions of fields such as an association identifier (11), partial bandwidth information (Partial BW Info), the first disambiguation field (disambiguation), a feedback type and Ng, a codebook size (codebook size), and a number of columns (Nc) can be consistent with the functions of corresponding fields of an HE NDPA in IEEE 802.11ax, except for the difference between a bit count of a part of the fields and a bit count of the corresponding fields in the HE NDPA of IEEE 802.11ax. In the following, we focus on the newly introduced functions. The enhanced station information field includes a bitmap field that occupies several bits (for example, four bits shown in FIG. 14). The bitmap field is used to indicate a portion of the antennas or a portion of the APs on which the second communicating device should perform channel scanning. The bitmap field may correspond to the first field above. For example, in an MP MIMO scenario, the field represents a bitmap of panels, and each bit represents a panel. In / n / zznz / q / YiAi another example, in a multi-AP coordination scenario, the field represents an AP bitmap, and each bit represents an AP. In this way, the specific panels or APs that should be surveyed by a specific STA can be determined based on both the association identifier 11 and the bitmap field of the station information field. Additionally, the enhanced station information field may include a new disambiguation field used to determine the type of NDPA frame. The new disambiguation field and the above standard control field may together constitute the above third field. Optionally, the new disambiguation field may be any bit following bit 32 (i.e., the 33ebit counted from 0) of the station information field, for example, bit 43 (i.e., the 44Qbit counted from 0) shown in FIG. 14. When a value of the disambiguation field is 0, it indicates that the NDPA frame is a VHT NDPA frame; or when a value of the disambiguation field is 1, it indicates that the NDPA frame is an EHT NDPA frame. Alternatively, when a value of the disambiguation field is 1, it indicates that the NDPA frame is a VHT NDPA frame; or when a disambiguation field value is 0, it indicates that the NDPA frame is an EHT NDPA frame. It should be understood that when Implementation 1 of the enhanced station information field is used with reference to Implementation 2 of the standard control field, the new disambiguation field may be used in the enhanced station information field to further determine the type of the NDPA frame, or the new disambiguation field may not be set. It should be understood that application 2 is also applicable to a multi-AP coordination scenario. Implementation 2 For MP MIMO, in Implementation 2, the functions of fields such as association identifier 11, partial bandwidth information, first disambiguation field, feedback type and Ng, codebook size, and number of columns included in the enhanced station information field are the same as those in Implementation 1, except for a change in the location of a portion of the fields. Only one operational difference is described below. In Implementation 2, the enhanced station information field does not include any bitmap fields, but includes an antenna filtering field occupying several bits (e.g., eight bits in FIG. 14). The antenna filtering field may correspond to the first field above. The antenna filtering field includes a start antenna index field and a end antenna index field.In this way, it can be determined, based on both the association identifier 11 and the antenna filtering field in the station information field / n / zznz / q / YiAi, that a specific STA needs to measure an antenna. Optionally, the final antenna index field in the antenna filtering field may be replaced by an antenna quantity field. It should be understood that application 2 is also applicable to a multi-AP coordination scenario. Implementation 3 In the MP MIMO and multi-AP coordination scenarios, in Implementation 3, the functions of fields such as association identifier 11, partial bandwidth information, first disambiguation field, feedback type and Ng, codebook size, and number of columns included in the enhanced station information field are the same as in Implementation 1, except for a change in the location of a portion of the fields. Only one operational difference is described below. In Implementation 3, several bits based on Implementation 1 are used to indicate whether a bitmap field is specifically a panel bitmap or an AP bitmap, and a field including these bits may correspond to the second field above. For example, as shown in FIGURE 14, a 1-bit multi-panel MIMO field and a 1-bit AP coordination field are introduced based on Implementation 1. If the two-bit values ​​are 10, the two bits represent multi-panel MIMO, and a trailing bitmap field represents a panel bitmap. If the two-bit values ​​are 01, the two bits represent multi-AP coordination, and a trailing bitmap field represents an AP bitmap. If the two-bit values ​​are 00, the two bits represent an EHT station general information field, and a trailing bitmap field is a reserved field. If the two-bit values ​​are 11, the two bits are reserved for future functions. In another example, based on Implementation 1, a bit is introduced to indicate whether the bitmap field is a panel bitmap or an AP bitmap. For example, when a bit value is 1, the bitmap field represents a panel bitmap; or when a bit value is 0, the bitmap field represents an AP bitmap. In another example, when a bit value is 0, the bitmap field represents a panel bitmap; or when a bit value is 1, the bitmap field represents an AP bitmap. Implementation 4 In the MP MIMO and multi-AP coordination scenarios, most of the functions of Implementation 4 are the same as those of Implementation 2, except for a change in the location of some fields. Only one difference in operation is described below. In Implementation 4, based on Implementation 2, several bits are used to indicate whether the bitmap field is specifically a panel bitmap or an AP bitmap, and a field that includes these bits can correspond to the second field above. For example, as shown in FIGURE 14, a 1-bit multi-panel MIMO field and a 1-bit AP coordination field are introduced based on Implementation 1. The functions of the two bits are similar to those in Implementation 3. The details are not described again here. In another example, based on Implementation 1, a bit is introduced to indicate whether the bitmap field is a panel bitmap or an AP bitmap. The functions of this bit are similar to those in Implementation 3. The details are not described herein again. Additionally, the first frame in this embodiment of this application may be a new control frame introduced in IEEE 802.11, and the functions of the first frame for an MP MIMO scenario or a multi-AP coordination scenario are implemented using a frame type or subtype (subtype) that is not used in a frame control field in existing IEEE 802.11. For example, the frame type field is 01, and the subtype field is 1111. The new control frame has similar functions to those of the previous enhanced NDPA frame. Because the new control frame is dedicated to the MP MIMO scenario or the AP coordination scenario, the new disambiguation field described above may not be set in the new control frame. It can be understood that the implementations of the first frame are merely examples, and there may alternatively be other implementations of the first frame. In another example, each field of the first frame may alternatively have other names. In another example, each field of the first frame may alternatively be a field of another length. In another example, the fields of the first frame may be arranged in another order. In another example, the first frame may alternatively include more or fewer fields. There may be many implementations of the enhanced NDP frame in this embodiment of this application, as long as the functions of the second frame can be implemented. In one example, the enhanced NDP frame includes fields related to legacy channel probing, e.g., a non-high-throughput short training field (L-STF), a non-high-throughput long training field (L-LTF), and a non-high-throughput signal field (L-SIG). The enhanced NDP frame further includes a portion of EHT-specific fields, e.g., an extremely high throughput short training field (EHT-STF), an extremely high throughput long training field (EHT-SIG), and an extremely high throughput signal field (EHT-SIG). There are many implementations of the EHT-specific field in the Enhanced NDP frame. This is not limited to this application modality. Implementation 1 As shown in FIGURE 15, the EHT-specific field includes an ETH-SIG, an ETH-STF, and an ETH-LTF. The ETH-LTFs of the antennas are ordered sequentially based on the panel and antenna indices. It can be seen that, in Implementation 1, the EHT-LTFs of the antennas are sent panel by panel and antenna by antenna. For example, the antennas mounted on panel 1 are cycled for sending, and then the antennas mounted on panel 2 are cycled for sending. This method is applied by analogy. It can be understood that a panel classification method and an antenna classification method are not limited in this embodiment of this application. Implementation 2 As shown in FIG. 16, the EHT-specific field includes an ETH-SIG, an ETH-STF, and an ETH-LTF. The ETH-LTFs include only the EHT-LTFs of a plurality of antennas on a panel. The ETH-LTFs of the plurality of antennas may be arranged sequentially based on antenna indices. The difference from Implementation 1 is that the EHT-LTFs of all panels are sent simultaneously. However, the EHT-LTFs of all panels are sent serially in Implementation 1. For example, when the antennas mounted on panel 1 are traversed for sending, the antennas mounted on panel 2 are also traversed for sending. It can be understood that a panel classification method and an antenna classification method are not limited in this embodiment of this application. Implementation 3 As shown in FIGURE 17, Implementation 3 is similar to Implementation 1, with one difference being that NDP frames from all panels are sent sequentially and independently, and there is a fourth preset time interval between NDP frames from two adjacent panels. The fourth preset time period can be of any length, e.g., one or more SIFSs. It should be noted that the above implementations of the enhanced NDP frame can be applied to different scenarios, for example, an MP MIMO scenario and a / n / zznz / q / YiAi multi-AP coordination scenario. The aforementioned antenna array may be an antenna predetermined by the first communication device and capable of communicating well with the second communication device. A corresponding determination method is described below. FIGURE 18 is a schematic diagram of a panel pre-training procedure according to one embodiment of this application. As shown in FIGURE 18, in step 1, an AP sends a training frame to some or all of the non-AP STAs. Optionally, as shown in FIGURE 18, an enhanced NDP frame can be reused as a training frame. The enhanced NDP frame is similar to the previous enhanced NDP frame, with one difference being that all antennas on each AP panel send an EHT-LTF signal simultaneously, rather than each antenna sending an EHT-LTF signal one by one. Optionally, as shown in FIG. 19, the training frame may alternatively be a plurality of continuously sent enhanced NDP frames, each enhanced NDP frame corresponding to a panel, and each enhanced NDP frame being sent by all antennas of the corresponding panel simultaneously. There is an interval of a fifth preset time period between two adjacent enhanced NDP frames. The fifth preset time period may be of any length, e.g., one or more SIFSs. Optionally, before the AP sends the enhanced NDP frame to some or all of the non-AP STAs, the AP may also send a pre-training frame to some or all of the non-AP STAs. The previous enhanced NDPA frame may be reused as a pre-training frame, the difference being that one or more bits of the enhanced NDPA frame must be occupied to indicate that the NDPA frame is a pre-training NDPA frame. For example, one bit of the reserved field in the four implementations shown in FIGURE 14 is changed to an NDPA type field. When a bit value is 1, it indicates that the NDPA frame is used for pre-training; or when a bit value is 0, it indicates that the NDPA frame is used for channel probing. Alternatively, when a bit value is 0, it indicates that the NDPA frame is used for pre-training; or when a bit value is 1, it indicates that the NDPA frame is used for channel probing. Stage 2: The non-AP STA receives the training frame sent by the AP, and determines one or more destination frames based on a preset indicator. pqa / / n / zznz / q / Yi / u Optionally, the one or more destination panels can communicate well with a STA. The preset indicator can be any indicator used to measure communication quality. For example, the preset indicator can be one or more indicators such as a received signal strength indicator (RSSI) and a signal-to-interference-and-noise ratio (SINR). Step 3: The AP sends a panel training trigger frame to some or all of the non-AP STAs, to schedule a corresponding non-AP STA to feed back a target panel determined by the non-AP STA. In some embodiments, the panel training trigger frame may further indicate a maximum value of a number of panels that are allowed to be fed back. For example, the panel training trigger frame indicates that the maximum value of the number of panels that are allowed to be fed back is 4, 5, 8, 11, 12, or the like. FIGURE 20 shows the frame structure of a plane training activation frame. The activation frame shown in FIGURE 20 is a new type of activation frame introduced based on an activation frame structure in IEEE 802.11ax. The activation frame shown in FIGURE 20 is a new type of activation frame introduced based on an activation frame structure in IEEE 802.11ax. The activation frame type field is used to indicate a type of activation frame. For example, when a value of the activation frame type field is 9, it indicates that the activation frame type is a panel training activation frame. The common information field is a field related to the activation type.For example, when the trigger frame type is a panel training trigger frame, the common information field may indicate a maximum value of a number of panels allowed to be fed back, i.e., a maximum number of planes that can be fed back by a non-AP STA. It can be understood that the maximum number of panels allowed to be fed back can also be specified by using a pre-training frame and / or a training frame, or the maximum number of panels allowed to be fed back can be defined as requiring no interaction. This is not limited to this particular embodiment of this application. Step 4: The non-AP STA sends a feedback frame about a resource allocated to the non-AP STA or about a resource obtained based on random contention, where the feedback frame is used to feed back one or more destination panels determined by the non-AP STA. Optionally, the feedback frame may be implemented by defining a new A-Control frame type in IEEE 802.11ax. The Control ID field may use any reserved type, for example, a type corresponding to a value of 7. A structure of the Control Information field may be shown in FIGURE 21. The Control Information field includes a panel number field and a panel identifier field. A value of the panel number field plus 1 equals the number of panels fed back this time, and the panel number field is followed by an identifier for each panel. Optionally, when the number of panels fed back is an agreed value, the control information field may not include a panel number field. In the above training process, the AP can learn from a target array fed back by each STA, i.e., learn from a set of antennas corresponding to each STA. In some embodiments, as shown in FIG. 22, the training frame may be sent via orthogonal frequency division multiple access (OFDMA). Alternatively, as shown in FIG. 23, the training frame may be sent via multiple user multiple input multiple output (MU-MIMO). In this case, the training frame need only include a panel identifier. In a multi-AP coordination scenario, in addition to the training process shown in FIGURE 18, it is necessary to perform an inter-AP training procedure. A multi-AP training procedure with a plurality of panels can be shown as follows. Stage 1: A primary AP in a multi-AP coordination group sends a pre-training frame to all secondary APs. Stage 2: The primary AP sends a training frame to all secondary APs. Step 3: The primary AP sends a wake-up frame to all secondary APs. Step 4: The secondary AP sends a feedback frame about a resource allocated to the secondary AP or about a resource obtained based on random contention, where the feedback frame includes one or more optimal service panels located between the secondary AP and the primary AP and selected by the secondary AP, and an interference state between the secondary AP and each STA. The interference state between the secondary AP and each STA may be obtained in the training process shown in FIG. 18, or may be obtained in another manner. This is not particularly limited to this embodiment of this application. FIGURE 24 shows a frame structure of a / n / zznz / q / YiAi feedback frame between a plurality of APs with a plurality of panels. As shown in FIGURE 24, the feedback frame includes an element identifier field, a length field, a panel information field, and a collision list field. The panel information field is used to indicate one or more optimal service panels between a secondary AP and a primary AP. The collision list field is used to indicate an interference state between the secondary AP and each STA. For example, the collision list field indicates a media access control (MAC) address of a STA that has an interference relationship with the secondary AP, a MAC address of a STA that does not have an interference relationship with the secondary AP, or the like. It should be understood that the modalities described in this description may be independent solutions or may be combined based on internal logic. All of these solutions fall within the scope of protection of this application. It can be understood that, to implement the functions in the above embodiments, the first communication device and the second communication device each include a hardware structure and / or a corresponding software module for performing each function. A person with ordinary skill in the art should readily understand that, in combination with the units and method steps in the examples described in the embodiments disclosed in this application, this application can be implemented by hardware or a combination of hardware and computer software. Whether a function is performed by hardware or computer software depends on the particular application scenarios and the design constraints of the technical solutions. FIGURE 25 and FIGURE 26 are schematic diagrams of structures of possible channel sounding apparatuses according to embodiments of this application. These apparatuses may be configured to implement functions of the first communication device or the second communication device in the above embodiments, and thus may also implement beneficial effects of the above embodiments. In embodiments of this application, the channel sounding apparatus may be the AP 1 shown in FIGURE 1, may be the STA 1 or STA 2 shown in FIGURE 1, or may be a module (e.g., a chip) used in an AP or a STA. As shown in FIGURE 25, an apparatus 2500 includes a processing unit 2510 and a transceiver unit 2520. The apparatus 2500 is configured to implement the functions of the first communication device or the second communication device in any of the above method embodiments. When the apparatus 2500 is configured to implement the functions of the first communication device in embodiments of the method, the transceiver unit 2520 is configured to send a first frame to the second communication device, where the first frame is used to instruct the second communication device to perform channel scanning on a portion of the antennas of the first communication device. The transceiver unit 2520 is further configured to send a second frame to the second communication device, where the second frame is used by the second communication device to perform channel scanning by the antennas. The transceiver unit 2520 is further configured to receive a third frame from the second communication device, where the third frame is used to indicate a result of performing channel scanning by the antennas. Alternatively, the transceiver unit 2520 is configured to send a first frame to the second communication device, where the first frame is used to instruct the second communication device to perform channel scanning on a portion of the communication devices in a group of communication devices to which the first communication device belongs. The transceiver unit 2520 is further configured to send a second frame to the second communication device, where the second frame is used by the second communication device to perform channel scanning on the communication devices. The transceiver unit 2520 is further configured to receive a third frame from the second communication device, where the third frame is used to indicate a result of performing the channel scanning on the communication devices. When the apparatus 2500 is configured to implement the functions of the second communication device in embodiments of the method, the transceiver unit 2520 is configured to receive a first frame from the first communication device, the first frame being used to instruct the second communication device to perform channel scanning on a portion of the antennas of the first communication device. The transceiver unit 2520 is further configured to receive a second frame sent by the first communication device, the second frame being used by the second communication device to perform channel scanning on the portion of the antennas. The processing unit 2510 is configured to perform channel scanning on the portion of the antennas based on the second frame.The transceiver unit 2520 is further configured to send a third frame to the first communication device, where the third frame is used to indicate a result of the channel scanning being performed by the antennas. Alternatively, the transceiver unit 2520 is configured to receive a first frame from the first communication device, the first frame being used to instruct the second communication device to perform channel scanning on a portion of the communication devices in a communication device group to which the first communication device belongs. The transceiver unit 2520 is further configured to receive a second frame sent by the first communication device, the second frame being used by the second communication device to perform channel scanning of the communication devices. The processing unit 2510 is configured to perform channel scanning of the communication devices based on the second frame.The transceiver unit 2520 is further configured to send a third frame to the first communication device, where the third frame is used to indicate a result of performing channel scanning by the communication devices. For a more detailed description of the processing unit 2510 and the transceiver unit 2520, refer directly to the description in the method embodiments. The details are not described herein again. As shown in FIG. 26, an apparatus 2600 includes a processor 2610 and an interface circuit 2620. The processor 2610 and the interface circuit 2620 are coupled together. It can be understood that the interface circuit 2620 may be a transceiver or an input / output interface. Optionally, the apparatus 2600 may further include a memory 2630, configured to store instructions executed by the processor 2610, store input data required by the processor 2610 to execute instructions, or store data generated after the processor 2610 executes instructions. When the apparatus 2600 is configured to implement the above methods, the processor 2610 is configured to perform functions of the processing unit 2510, and the interface circuit 2620 is configured to perform functions of the transceiver unit 2520. When the apparatus is a chip used in the first communication device, the chip implements the functions of the first communication device in the above embodiments. The chip receives information from another module (e.g., a radio frequency module or an antenna) of the first communication device, where the information is transmitted by the second communication device to the first communication device. Alternatively, the chip sends information to another module (e.g., a radio frequency module or an antenna) of the first communication device, where the information is transmitted by the first communication device to the second communication device. When the device is a chip used in the second communication device, the chip implements the functions of the second communication device in the above embodiments. The chip receives information from another module (e.g., a radio frequency module or an antenna) of the second communication device, where the information is then sent by the first communication device to the second communication device. qqr; / n / zznz / q / YiAi Alternatively, the chip sends information to another module (e.g., a radio frequency module or an antenna) of the second communication device, where the information is sent by the second communication device to the first communication device. It should be noted that the processor in the embodiments of this application may be a central processing unit (CPU), another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor. The method steps in embodiments of this application may be implemented through the use of hardware, or may be implemented by the execution of software instructions by the processor. The software instructions may include a corresponding software module. The software module may be stored in a random access memory (RAM), flash memory, read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically programmable EPROM (EEPROM), a register, a hard disk drive, a removable hard disk, a CD-ROM, or any other form of storage medium known in the art.For example, a storage medium is coupled to the processor, such that the processor can read information from the storage medium and write information to the storage medium. Indeed, the storage medium may be a component of the processor. The processor and the storage medium may be located in an ASIC. Additionally, the ASIC may be located in a network device or a terminal device. Indeed, the processor and the storage medium may alternatively exist in a network device or a terminal device as discrete components. All or part of the foregoing embodiments may be implemented through the use of software, hardware, firmware, or any combination thereof. When software is used to implement the embodiments, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When computer programs or instructions are loaded and executed on a computer, all or part of the procedures or functions are generated in accordance with the embodiments of this application. The computer may be a general-purpose computer, a dedicated computer, a computer network, or other programmable apparatus. The computer programs or instructions may be stored on a computer-readable storage medium, or they may be transmitted through the computer-readable storage medium.The computer-readable storage medium can be any usable medium accessible by a computer, or a data storage device such as a server that integrates one or more usable media. The usable medium can be a magnetic medium, for example, a floppy disk, a hard disk drive, or magnetic tape; or it can be an optical medium, for example, a DVD; or it can be a semiconductor medium, for example, a solid-state drive (SSD). It should be noted that in the embodiments of this application, a protocol may be a standard protocol in the field of communications, for example, it may include an LTE protocol, an NR protocol, a WLAN protocol, and a related protocol applied to a downstream communication system. This is not limited in this application. It should also be noted that, in the embodiments of this application, prefetching may include indication through device signaling or predefinition, for example, definition in a protocol. Predefinition may be implemented by preselecting the corresponding code or table in a device (e.g., the device includes a station and an access point), or it may be implemented in another manner that can be used to indicate related information. The specific implementation of predefinition is not limited in this application. For example, predefinition may be predefinition in a protocol. It should also be noted that storage in the embodiments of this application may refer to storage in one or more memories. The one or more memories may be arranged separately, or they may be integrated into an encoder, a decoder, a processor, or a communication device. Alternatively, a portion of one or more memories may be arranged separately, and a portion of one or more memories is integrated into a translator, a processor, or a communication device. A type of memory may be a storage medium of any form, and this is not limited in this application. It should also be noted that in the modalities of this application, "of," "corresponding," and "corresponding" are sometimes used interchangeably. It should be noted that, where the differences between the terms are not clearly stated, their meanings are the same. It should be noted that the term and / or describes an association relationship to describe associated objects and represents that three relationships may exist. For example, A and / or B qqrj / n / zznz / q / YiAi can represent the following three cases: Only A exists, both A and B exist, and only B exists. The character 7 usually indicates an or relationship between associated objects. The term at least one means one or more. The term at least one of A and B, similar to the term A and / or B, describes an association relationship between associated objects and represents that three relationships may exist. For example, at least one of A and B can represent the following three cases: Only A exists, both A and B exist, and only B exists. In the embodiments of this application, unless otherwise indicated or there is a logical collision, the terms and / or descriptions between the different embodiments are consistent and may be mutually referenced, and the technical characteristics of the different embodiments may be combined based on an internal logical relationship thereof, to form a new embodiment. It can be understood that the various numbers in the embodiments of this application are used merely for differentiation and ease of description, and are not used to limit the scope of the embodiments of this application. The sequence numbers of the above processes do not represent execution sequences. The execution sequences of processes should be determined according to the functions and internal logic of the processes. In the various embodiments provided in this application, it should be understood that the disclosed system, apparatus, and method may be implemented in other ways. For example, the above apparatus embodiments are merely examples. For example, the division into units is simply a division of logical function and may be further divided during actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not realized. Additionally, the mutual coupling shown or discussed, or the direct coupling or communication connection, may be implemented using certain interfaces. Indirect coupling or communication connection between the apparatus or units may be implemented electrically, mechanically, or otherwise. The units described as separate parts may or may not be physically separate. The components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across a plurality of network units. Some or all of the units may be selected based on actual requirements to achieve the objectives of the embodiment solutions. Additionally, the functional units in the embodiments of this application may be integrated into a processing unit, each of the units may exist alone physically, or two or more units are integrated into one unit. When the functions are implemented in the form of a functional software unit and are sold or used as a stand-alone product, the functions may be stored on a computer-readable storage medium. Based on this understanding, the technical solutions of this application, essentially, or the portion contributing to the prior art, or a part of the technical solutions, may be implemented in the form of a software product. The computer software product is stored on a storage medium, and includes several instructions for instructing a computing device (which may be, for example, a personal computer, a server, or a network device) to perform all or part of the steps of the methods described in the embodiments of this application.The above storage medium includes any medium that can store 10 program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or a compact disc. The above descriptions are merely specific implementations of this application, but are not intended to limit the scope of protection of this application. Any variation or substitution easily imaginable by a person skilled in the art within the technical scope disclosed in this application will be within the scope of protection thereof. Therefore, the scope of protection of this application will be subject to the scope of protection of the claims.

Claims

1. A channel scanning method, characterized in that it comprises: sending, by means of a first communication device, a first frame to a second communication device, wherein the first frame is used to instruct the second communication device to perform a channel scan on a portion of the antennas of the first communication device; sending, by means of the first communication device, a second frame to the second communication device, wherein the second frame is used by the second communication device to perform the channel scan on the portion of the antennas; and receiving, by means of the first communication device, a third frame from the second communication device, wherein the third frame is used to indicate a result of performing the channel scan on the portion of the antennas.

2. The method according to claim 1, characterized in that prior to the receipt, by means of the first communication device, of a third frame from the second communication device, the method further comprises: sending, by means of the first communication device, a fourth frame to the second communication device, wherein the fourth frame is used to instruct the second communication device to send the third frame to the first communication device.

3. The method according to claim 1 or 2, characterized in that prior to the transmission, by means of a first communication device, of a first frame to a second communication device, the method further comprises: sending, by the first communication device, a training frame to the second communication device, wherein the training frame is used to perform channel scanning on all the antennas of the first communication device; receiving, by the first communication device, a feedback frame from the second communication device; and determining, by means of the first communication device, the portion of the antennas based on the feedback frame.

4. The method according to claim 3, characterized in that prior to sending, by means of the first communication device, a training frame to the second communication device, the method further comprises: sending, by means of the first communication device, a pre-training frame to the second communication device, wherein the pre-training frame is used to instruct the second communication device to perform a channel scan on all antennas of the first communication device.

5. The method according to claim 3 or 4, characterized in that prior to the receipt, by means of the first communication device, of a feedback frame from the second communication device, the method further comprises: sending, by means of the first communication device, an activation frame to the second communication device, wherein the activation frame is used to instruct the second communication device to send the feedback frame to the first communication device.

6. The method according to any one of claims 1 to 5, characterized in that the first frame comprises a first field, wherein the first field is used to indicate a panel portion of the first communication device, and the antenna portion comprises an antenna corresponding to the panel portion.

7. The method according to any of claims 1 to 5, characterized in that the first frame comprises a first field, wherein the first field is used to carry an antenna index, and the antenna index is used to indicate the antenna portion.

8. The method according to claim 6 or 7, characterized in that the first frame further comprises a second field, wherein the second field is used to indicate that the first field is used to indicate a part of the panels of the first communication device or to carry an antenna index.

9. The method according to any of claims 1 to 8, characterized in that the first frame comprises a third field, wherein the third field is used to indicate that the first frame is a frame of an extremely high-performance EHT variant.

10. The method according to any of claims 1 to 8, characterized in that the first frame is a Null Data Packet Advertisement (NDPA) frame, and the first frame comprises a third field, wherein the third field comprises a standard control field; and when a value of the standard control field is 00, it indicates that the first frame is a Very High Throughput (VHT) variant frame; when a value of the standard control field is 01, it indicates that the first frame is a High Efficiency (HE) variant frame; when a value of the standard control field is 10, it indicates that the first frame is a Ranged variant frame; or when a value of the standard control field is 11, it indicates that the first frame is an Extremely High Throughput (EHT) variant frame.

11. The method according to any of claims 1 to 10, characterized in that the second frame comprises an extremely high performance (EHT) signal field, a short EHT training field, and a long EHT training field, wherein the antenna portion corresponds to at least two antenna panels, the second frame comprises at least two second subframes, and the long EHT training field in the second subframe comprises a long antenna training field corresponding to one of at least two antenna panels.

12. A channel scanning method, characterized in that it comprises: receiving, by means of a second communication device, a first frame from a first communication device, wherein the first frame is used to instruct the second communication device to perform a channel scan on a portion of the antennas of the first communication device; receiving, by means of the second communication device, a second frame sent by the first communication device, wherein the second frame is used by the second communication device to perform the channel scan on the portion of the antennas; and performing, by means of the second communication device, a channel scan on the portion of the antennas based on the second frame;and send, by means of the second communication device, a third frame to the first communication device, where the third frame is used to indicate a result of the channel scanning performed by the antennas.; 13. The method according to claim 12, characterized in that prior to the sending, by means of the second communication device, of a third frame to the first communication device, the method further comprises: receiving, by means of the second communication device, a fourth frame sent by the first communication device, wherein the fourth frame is used to instruct the second communication device to send the third frame to the first communication device.

14. The method according to claim 12 or 13, characterized in that prior to the reception, by means of a second communication device, of a first frame from a first communication device, the method further comprises: receiving, by the second communication device, a training frame from the first communication device, wherein the training frame is used to perform channel scanning on all antennas of the first communication device; and sending, by means of the second communication device, a feedback frame to the first communication device, such that the first communication device determines the portion of the antennas based on the feedback frame.

15. The method according to claim 14, characterized in that prior to the reception, by means of the second communication device, of a training frame from the first communication device, the method further comprises: receiving, by the second communication device, a pre-training frame sent by the first communication device, wherein the pre-training frame is used to instruct the second communication device to perform a channel scan on all antennas of the first communication device.

16. The method according to claim 14 or 15, characterized in that prior to the sending, by means of the second communication device, of a feedback frame to the first communication device, the method further comprises: receiving, by the second communication device, an activation frame from the first communication device, wherein the activation frame is used to instruct the second communication device to send the feedback frame to the first communication device.

17. The method according to any one of claims 12 to 16, characterized in that the first frame comprises a first field, wherein the first field is used to indicate a panel portion of the first communication device, and the antenna portion comprises an antenna corresponding to the panel portion.

18. The method according to any of claims 12 to 16, characterized in that the first frame comprises a first field, wherein the first field is used to carry an antenna index, and the antenna index is used to indicate the antenna portion.

19. The method according to claim 17 or 18, characterized in that the first frame further comprises a second field, wherein the second field is used to indicate that the first field is used to indicate a part of the panels of the first communication device or to carry an antenna index.

20. The method according to any of claims 12 to 19, characterized in that the first frame comprises a third field, wherein the third field is used to indicate that the first frame is an extremely high throughput (EHT) variant frame.

21. The method according to any of claims 12 to 19, characterized in that the first frame is a Null Data Packet Advertisement (NDPA) frame, and the first frame comprises a third field, wherein the third field comprises a standard control field; and when a value of the standard control field is 00, it indicates a frame of a Very High Throughput (VHT) variant; that the first frame is a frame of a High Efficiency (HE) variant; when a value of the standard control field is 01, it indicates a frame of a Ranged (Ranging) variant; or when a value of the standard control field is 01, it indicates that the first frame is a cqa; / n / zznz / q / YiAi is a frame of an Extremely High Throughput (EHT) variant.

22. The method according to any of claims 12 to 21, characterized in that the second frame comprises an extremely high performance (EHT) signal field, a short EHT training field, and a long EHT training field, wherein the antenna portion corresponds to at least two antenna panels, the second frame comprises at least two second subframes, and the long EHT training field in the second subframe comprises a long antenna training field corresponding to one of at least two antenna panels.

23. A channel probing apparatus, characterized in that it comprises: a memory, configured to store computer instructions; and a processor, configured to execute the computer instruction stored in the memory, to enable the channel probing apparatus to perform the method according to any one of claims 1 to 11, or to enable the channel probing apparatus to perform the method according to any one of claims 12 to 22.

24. A computer-readable storage medium configured to store computer instructions, characterized in that when the computer instructions are executed by a computer, the computer is enabled to perform the method in accordance with any one of claims 1 to 11, or the computer is enabled to perform the method in accordance with any one of claims 12 to 22.

25. A communication system, characterized in that it comprises a first channel sounding apparatus and a second channel sounding apparatus, wherein the first channel sounding apparatus is configured to perform the method in accordance with any one of claims 1 to 11, and the second channel sounding apparatus is configured to perform the method in accordance with any one of claims 12 to 22.

26. A computer program product, characterized in that it comprises instructions, wherein when the instructions are executed by a computer, the computer is enabled to perform the method in accordance with any one of claims 1 to 11, or the computer is enabled to perform the method in accordance with any one of claims 12 to 22.

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