Patent Publication Number: US-2019174383-A1

Title: Channel Automatic Selection and Switching Method and System, and Wireless Access Point

Description:
TECHNICAL FIELD 
     The present invention relates to the communications field, and in particular, to a channel automatic selection and switching method and system, a wireless access point, and a station. 
     BACKGROUND 
     Currently, a layer 2 in the OSI seven-layer model is a data link layer (Data Link Layer). According to IEEE 802.11. Wi-Fi mainly operates at the data link layer. The IEEE 802.11 Working Group defines a plurality of independent frequency bands, for example, 2.4 GHz and 4.9/5.8 GHz. Each frequency band is further divided into channels. For example, China&#39;s 2.4 GHz frequency band is 2.412 to 2.472 GHz, and the frequency band is further divided into 13 channels. However, as wireless access points (Access Point, AP) and stations (Station, STA) are increasing, interference between Wi-Fi is also increasing. Therefore, automatic selection of a relatively good channel becomes a mandatory function of a wireless access point. 
     At present, APs from some device vendors such as Qualcomm, Broadcom, and Realtek can support automatic selection of a relatively good channel, but support only automatic selection of a relatively good channel before a connection is established between an AP and a STA. After the connection is established between the AP and the STA, no AP from any vendor supports channel automatic selection and switching without interrupting a data link layer connection. 
     In the prior art, an AP does not detect quality of an operating channel, and a user of a STA determines quality of the operating channel. When the quality of the operating channel deteriorates and consequently data cannot be normally received or sent, the user manually interrupts the connection between the AP and the STA, then establishes a connection between the AP and the STA, and in a process of re-establishing the connection, automatically selects a relatively good channel, thereby completing channel reselection and switching. Therefore, in an operating channel switching process after the connection is established between the AP and the STA, the data link layer connection between the AP and the STA is interrupted for a period of time. 
     Currently, it is quite common that a new STA and other interference appear on a channel of a frequency band. Therefore, after the connection is established between the AP and the STA, channel quality deterioration inevitably occurs. Therefore, after the connection is established between the AP and the STA, how the AP performs automatic selection and switching of the operating channel without interrupting the data link layer connection becomes a problem to be urgently resolved. 
     SUMMARY 
     Embodiments of the present invention provide a channel automatic selection and switching method and system, and a wireless access point. The following problem can be resolved: An AP cannot perform channel automatic selection or switching without interrupting a data link layer connection after the AP establishes a connection to a STA. 
     According to a first aspect, an embodiment of the present invention provides a channel automatic selection and switching method. The method includes: after an access point (Access Point, AP) establishes a connection to a station (Station, STA) by using an operating VAP (Virtual Access Point, VAP), performing, by the AP, quality detection on an operating channel to obtain a first quality detection result, where the operating VAP is a VAP through which the AP provides a service for the STA, and the operating channel is a channel in which the operating VAP is located; determining, by the AP based on the first quality detection result, whether the operating channel needs to be switched; if the operating channel needs to be switched, performing, by the AP, quality detection on a plurality of backup channels to obtain a plurality of second quality detection results, where the plurality of backup channels are some or all channels other than the operating channel, and the plurality of backup channels and the operating channel use same network connection information; determining, by the AP, a target channel based on the plurality of second quality detection results; sending, by the AP, a notification message to instruct the STA to perform operating channel switching, where the notification message carries the target channel; switching, by the STA, the operating channel to the target channel; and switching, by the AP, the operating channel to the target channel. 
     Therefore, according to the channel automatic selection and switching method provided in this embodiment of the present invention, after the AP and the STA are successfully connected, the AP performs quality detection on the operating channel, and then determines, based on the quality detection result, whether the operating channel needs to be switched. If the operating channel needs to be switched, the AP performs quality detection on the backup channels, and if there is a backup channel of higher quality, channel switching for the AP and the STA is started. Because the backup channel and the operating channel use the same network connection information, when the AP and the STA perform operating channel switching, a data link layer connection interruption phenomenon does not occur, thereby ensuring that operating channel switching is completed without interrupting a data link layer connection between the AP and the STA. 
     With reference to the first aspect, in a first possible implementation, the method further includes: after the determining, by the AP, a target channel based on the second quality detection result and before the sending, by the AP, a notification message to instruct the STA to perform operating channel switching, suspending, by the AP, sending of data to the STA; and after the STA receives the notification message and before the switching, by the STA, the operating channel to the target channel, suspending, by the STA, sending of data to the AP. 
     Therefore, in the first possible implementation, before sending an operating channel switching message to the STA, the AP suspends sending of data to the STA. Before performing operating channel switching, the STA suspends sending of data to the AP. Data transmission between the AP and the STA can be normally started after the operating channel of both the AP and the STA is switched to the target channel. In this way, integrity of data sent between the AP and the STA is effectively ensured. 
     With reference to the first aspect or the foregoing possible implementation, in a second possible implementation, the determining, by the AP based on the first quality detection result, whether the operating channel needs to be switched includes: determining, by the AP based on a result of whether the first quality detection result meets a first switching condition, whether the operating channel needs to be switched, where that the first switching condition is met is: a value of a first parameter in the first quality detection result reaches a preset threshold of the first parameter; or a value of a first parameter in the first quality detection result reaches a preset threshold of the first parameter, a value of a second parameter reaches a preset threshold of the second parameter, and a weighted value of the first parameter and the second parameter reaches a preset threshold of the weighted value. 
     With reference to the first aspect or the foregoing possible implementations, in a third possible implementation, the determining, by the AP, a target channel based on the plurality of second quality detection results includes: comparing, by the AP, the plurality of second quality detection results, and selecting a channel of highest quality from the plurality of backup channels as the target channel. 
     With reference to the first aspect or the foregoing possible implementations, in a fourth possible implementation, the AP compares the plurality of second quality detection results with a second switching condition, and selects a channel of which the second quality detection result meets the second switching condition as the target channel, where that the second switching condition is met is: a value of a second parameter in the plurality of second quality detection results reaches a preset threshold of the second parameter; or a value of a second parameter in the second quality detection result reaches a preset threshold of the second parameter, a value of a third parameter reaches a preset threshold of the third parameter, and a weighted value of the second parameter and the third parameter reaches a preset threshold of the weighted value. 
     With reference to the first aspect or the foregoing possible implementations, in a fifth possible implementation, the network connection information includes a service set identifier (Service Set Identifier. SSID), a basic service set identifier (Basic Service Set Identifier. BSSID), an encryption mode, key information, state machine information, and a user equipment identifier. 
     With reference to the fourth possible implementation, in a sixth possible implementation, the comparing, by the AP, the plurality of second quality detection results with a second switching condition, and selecting a channel of which the second quality detection result meets the second switching condition as the target channel specifically includes: detecting, by the AP, channel quality of all backup channels to obtain a plurality of second quality detection results; randomly selecting the second quality detection result from the plurality of second quality detection results; comparing the selected second quality detection result with the second switching condition; and using a channel of which the second quality detection result meets the second switching condition as the target channel. 
     Therefore, in the sixth possible implementation, the AP may detect the channel quality of all the backup channels and randomly select a comparison object from the plurality of second quality detection results. When the comparison object does not meet the second switching condition, a channel corresponding to the comparison object cannot be used as the target channel and a next comparison object is selected. When the comparison object meets the second switching condition, a channel corresponding to the comparison object is determined as the target channel and it is unnecessary to select a next comparison object for comparison with the second switching condition. In this way, the target channel can be rapidly determined, and therefore operating channel switching can be rapidly completed, thereby resolving, as soon as possible, a problem caused by operating channel quality deterioration. 
     With reference to the fourth possible implementation, in a seventh possible implementation, the comparing, by the AP, the plurality of second quality detection results with a second switching condition, and selecting a channel of which the second quality detection result meets the second switching condition as the target channel specifically includes: selecting, by the AP, a specific backup channel, where there is no interference between the specific backup channel and the operating channel; and detecting, by the AP, channel quality of the specific backup channel to obtain a second quality detection result, and if the second quality detection result meets the second switching condition, determining the specific backup channel as the target channel. 
     Therefore, in the seventh possible implementation, in a relatively good case, the AP can find the target channel by performing quality detection on only one backup channel and does not need to perform quality detection on another backup channel. The target channel can be determined as soon as possible even when the AP needs to perform quality detection on the plurality of backup channels. In this way, the AP can determine the target channel more rapidly and therefore the AP can rapidly complete operating channel switching, thereby resolving, as soon as possible, a problem caused by operating channel quality deterioration. 
     According to a second aspect, an embodiment of the present invention provides an AP. The AP is configured to implement, by using hardware/software, functions of the method that are executed by the AP in the first aspect, and the hardware/software includes units corresponding to the foregoing functions. 
     According to a third aspect, an embodiment of the present invention provides a STA. The STA is configured to implement, by using hardware/software, functions of the method that are executed by the STA in the first aspect, and the hardware/software includes units corresponding to the foregoing functions. 
     According to a fourth aspect, an embodiment of the present invention provides an AP, including a processor, a network interface, a memory, and a communications bus. The communications bus is configured to implement communication between the processor, the network interface, and the memory, and the processor executes a program stored in the memory to perform the steps in the method for the AP in the first aspect. 
     According to a fifth aspect, an embodiment of the present invention provides a STA, including a processor, a network interface, a memory, and a communications bus. The communications bus is configured to implement communication between the processor, the network interface, and the memory, and the processor executes a program stored in the memory to perform the steps that are performed by the STA in the first aspect. 
     According to a sixth aspect, an embodiment of the present invention provides a system. The system includes the AP and the STA in the foregoing aspects. 
     According to a seventh aspect, an embodiment of the present invention provides a computer storage medium. The computer storage medium is configured to store a computer software instruction used by the foregoing AP, and the computer software instruction includes a program related to execution of the foregoing aspects. 
     According to an eighth aspect, an embodiment of the present invention provides a computer storage medium. The computer storage medium is configured to store a computer software instruction used by the foregoing STA, and the computer software instruction includes a program related to execution of the foregoing aspects. 
     In comparison with the prior art, the embodiments of the present invention provide a channel automatic selection and switching method and system, and a wireless access point. After the AP and the STA are successfully connected, the AP performs quality detection on the operating channel, and then determines, based on the quality detection result, whether the operating channel needs to be switched. If the operating channel needs to be switched, the AP performs quality detection on the backup channels, and if there is a backup channel of higher quality, channel switching for the AP and the STA is started. Because the backup channel and the operating channel use the same network connection information, when the AP and the STA perform operating channel switching, a data link layer connection interruption phenomenon does not occur, thereby ensuring that operating channel switching is completed without interrupting a data link layer connection between the AP and the STA. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       To describe the technical solutions in the embodiments of the present invention or in the prior art more clearly, the following briefly describes the accompanying drawings required for describing the embodiments or the prior art. Apparently, the accompanying drawings in the following description show merely some embodiments of the present invention, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts. 
         FIG. 1  is a diagram (before channel switching) of a connection between an AP and at least one STA according to an embodiment of the present invention; 
         FIG. 2  is a flowchart of channel automatic selection and switching according to an embodiment of the present invention; 
         FIG. 3  is a diagram (after channel switching) of a connection between an AP and at least one STA according to an embodiment of the present invention; 
         FIG. 4  is another diagram (before channel switching) of a connection between an AP and at least one STA according to an embodiment of the present invention: 
         FIG. 5  is another diagram (after channel switching) of a connection between an AP and at least one STA according to an embodiment of the present invention; 
         FIG. 6  is another flowchart of channel automatic selection and switching according to an embodiment of the present invention; 
         FIG. 7  is a schematic structural diagram of an AP according to an embodiment of the present invention; and 
         FIG. 8  is a schematic structural diagram of a STA according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely some but not all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. 
       FIG. 1  is a diagram (before channel switching) of a connection between an AP and at least one STA according to an embodiment of the present invention. As shown in  FIG. 1 , a virtual access point (Virtual Access Point, VAP) is configured on the AP. The VAP provides a service for all STAs (STA  1 , STA  2 , . . . , STA n, where n is greater than or equal to 1) that are connected to the AP. The AP stores network connection information of the VAP and the STA, and the network connection information is information required for establishing a connection between the VAP and the STA, including a service set identifier (Service Set Identifier, SSID), a basic service set identifier (Basic Service Set Identifier, BSSID), an encryption mode, key information, state machine information, and a user equipment identifier.  FIG. 1  shows only an operating VAP and an operating channel before channel switching. For example, the operating VAP is a VAP  1 , and the operating channel is a channel  1 . 
       FIG. 2  is a flowchart of channel automatic selection and switching according to an embodiment of the present invention. As shown in  FIG. 2 , this embodiment of the present invention is elaborated and described for how an AP performs automatic selection and switching on an operating channel without interrupting a data link layer connection after the AP and a STA are successfully connected. 
     It should be noted that the AP may include a plurality of VAPs, one VAP corresponds to one channel, and network connection information the same as that of an operating VAP is configured on each VAP. These VAPs may be a plurality of logical interfaces that are virtualized by a same network interface of the AP, or may be a plurality of logical interfaces that are virtualized by a plurality of network interfaces of the AP, and the network interface may be a radio-frequency physical interface. A person skilled in the art may understand how a VAP is created, and details are not described in this embodiment of the present invention. For example, if an AP supports China&#39;s 2.4 GHz frequency band of 2.412 to 2.472 GHz and the frequency band includes 13 channels, the AP may include a VAP  1 : a channel  1 , a VAP  2 : a channel  2 , . . . , a VAP  12 : a channel  12 , and a VAP  13 : a channel  13 . In a process of connecting the AP and the STA, the AP establishes a connection to the STA by using one VAP. The VAP is an operating VAP. The operating VAP is a VAP that is on the AP and that currently provides a service for the STA, and the operating channel is a channel in which the operating VAP is located. A backup VAP is a VAP that currently does not provide any service for the STA. The backup VAP may be configured before being used, or may start to be configured when needing to be used. Because all the VAPs use the same network connection information, a data link layer connection interruption phenomenon does not occur when the AP and the STA perform operating channel switching, thereby ensuring that operating channel switching is completed without interrupting the data link layer connection between the AP and the STA. 
     Step  200 : The AP performs quality detection on the operating channel to obtain a first quality detection result. 
     It should be noted that the AP may perform quality detection on the operating channel in real time or periodically. 
     In the prior art, the AP does not detect quality of the operating channel. When the quality of the operating channel deteriorates and consequently data cannot be normally received or sent, a user manually interrupts the connection between the AP and the STA and then establishes a connection between the AP and the STA. In a process of re-establishing a connection, the AP detects quality of channels and selects a relatively good channel to connect to the STA, so as to switch the operating channel to the relatively good channel. An entire process needs the user&#39;s manual participation, and the connection between the AP and the STA is interrupted for a period of time. 
     The first quality detection result may include a received signal strength indicator (Received Signal Strength Indication, RSSI) of the operating channel, a packet error rate (Packet Error Rate, PER) of the operating channel, or a signal-to-noise ratio of the operating channel. The quality detection result may further include another parameter, as long as the another parameter can reflect quality of the operating channel. No specific limitation is imposed in this embodiment of the present invention. 
     Step  201 : Determine, based on the first quality detection result, whether the operating channel needs to be switched. If the operating channel needs to be switched, step  202  is performed. If the operating channel does not need to be switched, step  200  is performed. 
     When determining, based on the first quality detection result, whether the operating channel needs to be switched, the AP needs to compare the first quality detection result with a first switching condition to determine whether the operating channel needs to be switched. 
     Specifically, when the first quality detection result meets the first switching condition, it is determined that the operating channel needs to be switched; or when the first quality detection result does not meet the first switching condition, it is determined that the operating channel does not need to be switched. 
     That the first switching condition is met is: a value of a first parameter in the first quality detection result reaches a preset threshold of the first parameter; or a value of a first parameter in the first quality detection result reaches a preset threshold of the first parameter, a value of a second parameter reaches a preset threshold of the second parameter, and a weighted value of the first parameter and the second parameter reaches a preset threshold of the weighted value. “First parameter” or “second parameter” herein represents any parameter in the first quality detection result, and is not limited in a quantity, and a plurality of first parameters or a plurality of second parameters may be included. How to specifically set the first switching condition is not specifically limited in this embodiment of the present invention. 
     It should be noted that “reaching” a preset threshold of a corresponding parameter includes being greater than or equal to the preset threshold of the corresponding parameter, being less than or equal to the preset threshold of the corresponding parameter, or the like. A specific expressed meaning needs to be limited depending on an actual parameter because some smaller parameters may indicate lower link quality, or conversely some larger parameters may indicate lower link quality, or when a value of a parameter is equal to a preset enumerated value, it indicates that a corresponding preset threshold is reached. For example, that a value of an RSSI is less than or equal to a preset threshold of the RSSI is defined as that the first switching condition is met, and in this case, it is determined that the operating channel needs to be switched. Alternatively, that a value of an RSSI is less than or equal to a preset threshold of the RSSI and a value of a PER is greater than or equal to a preset threshold of the PER is defined as that the first switching condition is met, and in this case, it is determined that the operating channel needs to be switched. Which parameters to be specifically used and how to set a preset threshold of a parameter may be set depending on an actual need of a product design, and no specific limitation is imposed in this embodiment of the present invention, as long as the setting can help identify that the operating channel needs to be switched. 
     It should be noted that the first switching condition may be configured on the AP at an initial networking stage or prestored before the AP is delivered. 
     Step  202 : Perform quality detection on a plurality of backup channels to obtain a plurality of second quality detection results, where each backup channel corresponds to one second quality detection result. 
     It should be noted that the plurality of backup channels are some or all channels other than the operating channel, and the plurality of backup channels and the operating channel use same network connection information. 
     Specifically, all channels other than the operating channel may be detected, for example, quality of a channel  2 , a channel  3  . . . . , a channel  12 , and a channel  13  may be detected in sequence. All channels that absolutely have no interference to the operating channel may alternatively be detected, for example, quality of a channel  6 , a channel  7 , . . . , a channel  12 , and a channel  13  may be detected in sequence. Some channels that absolutely have no interference to the operating channel may alternatively be detected, for example, a channel  6  and a channel  13  may be detected in sequence. 
     Step  203 : Determine a target channel based on the plurality of second quality detection results. As shown in  FIG. 2 , it is assumed that the channel  6  is determined as the target channel based on the plurality of second quality detection results. Herein, that the determined target channel is the channel  6  is described only as an example. A specific channel to be used as the target channel needs to be determined based on an actual detection result. 
     The determining a target channel based on the plurality of second quality detection results may be performed in the following manners: 
     Manner 1: The plurality of second quality detection results are compared, and a channel of highest quality is selected from the plurality of backup channels as the target channel. In this way, the optimal channel can be selected from the backup channels to serve the STA, thereby implementing network optimization. 
     Manner 2: The AP compares the plurality of second quality detection results with a second switching condition, and selects a channel of which the second quality detection result meets the second switching condition as the target channel. That the second switching condition is met is: a value of a second parameter in the plurality of second quality detection results reaches a preset threshold of the second parameter; or a value of a second parameter in the second quality detection result reaches a preset threshold of the second parameter, a value of a third parameter reaches a preset threshold of the third parameter, and a weighted value of the second parameter and the third parameter reaches a preset threshold of the weighted value. “Second parameter” or “third parameter” herein represents any parameter in the second quality detection result, and is not limited in a quantity, and a plurality of second parameters or a plurality of third parameters may be included. How to specifically set the second switching condition is not specifically limited in this embodiment of the present invention. 
     Specifically, the AP may determine the target channel after performing quality detection on all the backup channels. The AP may detect channel quality of all the backup channels and randomly select a comparison object from the plurality of second quality detection results. When the comparison object does not meet the second switching condition, a channel corresponding to the comparison object cannot be used as the target channel and a next comparison object is selected. When the comparison object meets the second switching condition, a channel corresponding to the comparison object is determined as the target channel. In this way, the target channel can be rapidly determined, and therefore operating channel switching can be rapidly completed, thereby resolving, as soon as possible, a problem caused by operating channel quality deterioration. 
     Certainly, the AP may alternatively compare all the second quality detection results with the second switching condition to obtain channels that meet the second switching condition, and then randomly select one channel from the obtained channels as the target channel or alternatively select an optimal channel from the obtained channels as the target channel. 
     The AP may alternatively detect channel quality of one backup channel to obtain one second quality detection result, use the second quality detection result as a comparison object, and determine whether the backup channel can be used as the target channel. Specifically, some channels that absolutely have no interference to the operating channel may be detected. For example, the operating channel is a channel  1 , and the AP may detect a channel  6  and a channel  13  in sequence. After the second quality detection result is obtained through quality detection on the channel  6 , whether the channel  6  meets the second switching condition is determined. If it is determined that the channel  6  meets the second switching condition, the AP may directly determine the channel  6  as the target channel. In this case, the AP performs quality detection on only one backup channel and there is no need to further perform quality detection on another backup channel. The target channel can be determined as soon as possible even when the AP needs to perform quality detection on the plurality of backup channels. In this way, the AP can determine the target channel more rapidly and therefore the AP can rapidly complete operating channel switching, thereby resolving, as soon as possible, a problem caused by operating channel quality deterioration. 
     It should be noted that parameters used in the two switching conditions, that is, the first switching condition and the second switching condition, in this application all are parameters in quality detection. A difference lies in that preset thresholds corresponding to the parameters are different. From the perspective of descending order of link quality, link quality when the second switching condition is met is higher than link quality when the first switching condition is met. To be specific, when the AP detects that the RSSI of the operating channel is less than R1 (the first switching condition), it indicates that a current network status is already poor, and switching of the operating channel needs to be started; otherwise, a case such as a packet loss may occur. When switching of the operating channel is started, the AP needs to detect an RSSI of a backup channel and select a channel of which an RSSI is greater than R2 (the second switching condition) as a target standby device. R2 is greater than R1. 
     Step  204 : The AP sends a notification message to instruct the STA to perform operating channel switching, where the notification message carries the target channel (the channel  6 ).  FIG. 2  uses only one STA as an example. If a plurality of STAs use the operating channel to perform data transmission with the AP, the AP needs to send the notification message to all the STAs that use the operating channel to perform data transmission with the AP so that all the STAs switch the operating channel to the target channel. 
     Optionally, a CSA Notify message in 802.11h may be used as the notification message. A specific structure of the CSA Notify message is as follows: 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Category 
                 Action 
                 Channel Switch Announcement element 
               
               
                   
                   
               
            
           
         
       
     
     “Category” occupies one byte, has a fixed value of 0, and indicates frequency spectrum management. “Action” occupies one byte, has a fixed value of 4, and indicates that this frame is CSA. “Channel Switch Announcement element” occupies five bytes, each byte is used to store one field, and byte formats and field meanings are as follows: 
     
       
         
           
               
               
               
               
               
             
               
                   
               
             
            
               
                 Element ID 
                 Length 
                 Channel Switch 
                 New Channel 
                 Channel Switch 
               
               
                   
                   
                 Mode 
                 Number 
                 Count 
               
               
                   
               
            
           
         
       
     
     “Length” has a fixed value of 3. “Channel Switch Mode” is set to 1, used to notify the STA that the AP is to deliver a new operating channel. “New Channel Number” is a value of the new operating channel. “Channel Switch Count” is an occasion for switching to the new channel, 0 indicates any random occasion after a CSA packet, and 1 indicates that switching is started after a fixed time period. 
     Step  205 : The STA switches the operating channel to the target channel (the channel  6 ). In  FIG. 2 , the STA switches the operating channel to the channel  6 . 
     The STA may complete operating channel switching based on a switching occasion specified in the CSA message. Certainly, the AP may not specify a switching occasion for the STA, and the STA itself determines when to perform operating channel switching. 
     Optionally, the STA may send an operating channel switching completion response message to the AP, after operating channel switching is completed. In this case, by using the response message, the AP may learn that the operating channel of the STA has been switched and a next operation may be performed, for example, step  206  is performed. If the AP has not received the response message within a preset time, the AP may resend a notification message to notify the STA of the target channel again, thereby ensuring that operating channel switching is completed for the AP and the STA. 
     Step  206 : The AP switches the operating channel to the target channel. As shown in  FIG. 2 , the AP switches the detected operating channel to the channel  6 . Because one VAP corresponds to one channel, since the operating channel is switched, the operating VAP is switched accordingly. The AP uses a VAP (a VAP  6 ) corresponding to the channel  6  to perform data transmission with the STA on the channel  6 . 
     The AP may configure, after receiving the response message from the STA, the target channel as an operating channel that serves the STA, or may directly configure, without waiting for the response message from the STA, the target channel as an operating channel that serves the STA. 
     Now, operating channel switching is completed, and the AP performs data transmission with the STA on the new operating channel (the target channel). Before operating channel switching, the AP and the STA use the VAP  1  (a VAP corresponding to the channel  1 ) to perform data transmission by using the channel  1 . After operating channel switching, the AP and the STA use the VAP  6  (a VAP corresponding to the channel  6 ) to perform data transmission by using the channel  6 . 
     Therefore, according to the channel automatic selection and switching method provided in this embodiment of the present invention, after the AP and the STA are successfully connected, the AP performs quality detection on the operating channel, and then determines, based on the quality detection result, whether the operating channel needs to be switched. If the operating channel needs to be switched, the AP performs quality detection on the backup channels, and if there is a backup channel of higher quality, channel switching for the AP and the STA is started. Because the backup channel and the operating channel use the same network connection information, when the AP and the STA perform operating channel switching, a data link layer connection interruption phenomenon does not occur, thereby ensuring that operating channel switching is completed without interrupting a data link layer connection between the AP and the STA. 
       FIG. 3  is a diagram (after channel switching) of a connection between an AP and at least one STA according to an embodiment of the present invention. In  FIG. 3 , after the AP and the STA in  FIG. 1  perform the channel automatic selection and switching procedure shown in  FIG. 2 , an operating VAP that is on the AP and provides a service for the STA is switched from a VAP  1  to a VAP  6 , and an operating channel of the AP and the STA is switched from a channel  1  to a channel  6 . 
       FIG. 4  is another diagram (before channel switching) of a connection between an AP and at least one STA according to an embodiment of the present invention. As shown in  FIG. 4 , a plurality of VAPs are configured on the AP, and one VAP may provide a service for one or more STAs.  FIG. 4  shows only partial information before channel switching. For example, an operating channel of a VAP  1  is a channel  1 , which means that the AP uses the VAP  1  to provide a service for a STA  1  and a STA  2  by using the channel  1 . An operating channel of a VAP  13  is a channel  13 , which means that the AP uses the VAP  13  to provide a service for a STA m by using the channel  13 . 
       FIG. 5  is another diagram (after channel switching) of a connection between an AP and at least one STA according to an embodiment of the present invention. In this case, quality of an operating channel of a VAP  1  deteriorates, and an operating channel of a VAP  13  is normal. In  FIG. 5 , after the AP and the plurality of STAs in  FIG. 4  perform the channel automatic selection and switching procedure shown in  FIG. 2 , the operating channel of the VAP  1  on the AP, a STA  1 , and a STA  2  is switched from a channel  1  to a channel  6 , an operating VAP is switched to a VAP  6 , and an operating channel of a VAP  13  and a STA m and an operating VAP remain unchanged. 
     It should be noted that there may be only one operating VAP on the AP, and correspondingly, there is only one operating channel. As shown in  FIG. 1 , there is a VAP  1  on an AP, and in this case, the AP needs to perform quality detection on only an operating channel of the VAP  1 . Alternatively, there may be a plurality of operating VAPs on the AP, and correspondingly, there are a plurality of operating channels on the AP. As shown in  FIG. 3 , there is a VAP  1  and a VAP  13  on an AP, and correspondingly, there are two operating channels on the AP. In this case, the AP needs to perform quality detection on an operating channel of the VAP  1  and an operating channel of the VAP  13 . The method shown in  FIG. 2  may be used to perform detection on both of the two operating channels. 
       FIG. 6  is another flowchart of channel automatic selection and switching according to an embodiment of the present invention. Some modifications are made in  FIG. 6  on the basis of  FIG. 2 . The following describes in detail only the modifications. For a same part, refer to related descriptions of  FIG. 2 . 
     After step  203  and before step  204 , the method further includes: 
     Step  601 : The AP suspends sending of data to the STA, to ensure that data sent by the AP to the STA is not lost. 
     After step  204  and before step  205 , the method further includes: 
     Step  602 : The STA suspends sending of data to the AP, to ensure that data sent by the STA to the AP is not lost. 
     Therefore, according to the channel automatic selection and switching method provided in this embodiment of the present invention, before sending an operating channel switching message to the STA, the AP suspends sending of data to the STA. Before performing operating channel switching, the STA suspends sending of data to the AP. Data transmission between the AP and the STA can be normally started after the operating channel of both the AP and the STA is switched to the target channel. In this way, integrity of data sent between the AP and the STA is effectively ensured. 
     According to the channel automatic selection and switching method provided in this embodiment of the present invention, channel switching prompt information may be presented on the STA to prompt a user of the STA that the AP has automatically completed channel optimization. This resolves an operating channel quality deterioration problem, thereby effectively improving AP and STA user experience. A specific prompt method may be notifying the user of the STA in a form of text on a screen of the STA, or may be notifying the user of the STA in a form of a sound. A specific manner to be used needs to be set depending on an actual need, and no specific limitation is imposed in the present invention. 
     An embodiment of the present invention provides an AP. Referring to  FIG. 7 .  FIG. 7  is a schematic structural diagram of an AP according to an embodiment of the present invention. The AP includes a processor  71 , a network interface  72 , a memory  73 , and a communications bus  74 . The communications bus  74  is configured to implement connection communication between the processor  71 , the network interface  72 , and the memory  73 . The network interface  72  includes one or more VAPs, and the VAPs are configured to provide a service for one or more STAs. The processor  71  executes a program that is stored in the memory  73  and executed by the AP. 
     An embodiment of the present invention provides a STA. Referring to  FIG. 8 .  FIG. 8  is a schematic structural diagram of a STA according to an embodiment of the present invention. The STA includes a processor  81 , a network interface  82 , a memory  83 , and a communications bus  84 . The communications bus  84  is configured to implement connection communication between the processor  81 , the network interface  82 , and the memory  83 . The processor  81  executes a program that is stored in the memory  83  and executed by the STA. 
     An embodiment of the present invention provides a channel automatic selection and switching system, including the AP shown in  FIG. 7  and the STA shown in  FIG. 8 . 
     In the specification, claims, and accompanying drawings of the present invention, the terms “first”, “second”, “third”, and so on are intended to distinguish between different objects but do not indicate a particular order. It should also be understood that, the term “and/or” used herein indicates and includes any or all possible combinations of one or more associated listed items. It should be further understood that the term “include” adopted in the specification specifies presence of features, integers, steps, operations, elements and/or components, with presence or attachment of other features, integers, steps, operations, components, elements, and their combinations not excluded. 
     All or some of the steps of the method embodiments may be implemented by a program instructing relevant hardware. The program may be stored in a computer-readable storage medium. When the program runs, the steps of the method embodiments are performed. The foregoing storage medium includes: any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (Read Only Memory, ROM for short), a random access memory (Random Access Memory, RAM for short), a magnetic disk, or an optical disc. 
     The foregoing descriptions are merely specific implementations of the present invention, but are not intended to limit the protection scope of the present invention. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.