CN107333307A - A method and device for switching access points in a wireless local area network - Google Patents

Abstract

Switch the method and apparatus of access point in a kind of WLAN, for enabling the STA in battery saving mode to carry out AP switchings.This method includes：First AP determines the STA that is connected with the first AP in battery saving mode, wherein, the first AP provides service based on the BSSID corresponding to the STA for the STA, the BSSID corresponding to the STA from and other any STA in same ESS of STA corresponding to BSSID it is different；First AP determines that the 2nd AP in same ESS switches latter linked target AP for the STA；First AP sends wake-up association to the STA, and the wake-up association is used to indicate that the STA is in wake states when the 2nd AP sends beacon frame based on the BSSID corresponding to the STA；First AP sends switching command to the 2nd AP, and the switching command is used to indicate that the 2nd AP provides service based on the BSSID corresponding to the STA for the STA.

Description

A method and device for switching access points in a wireless local area network

technical field

The invention relates to the field of communication technology, in particular to a method and equipment for switching an access point AP in a wireless local area network (WLAN).

Background technique

In a wireless local area network (English: wireless local area networks, WLAN) system, a terminal needs to be connected to an access point (English: access point, AP), and transmit and receive data through the AP. During the communication process, the signal between the terminal and the currently connected AP may become poor. For example, when the distance between the terminal and the first currently connected AP becomes longer, the signal between them becomes poor. When the signal quality between the terminal and the first AP currently connected is lower than the threshold, the terminal will initiate an association request to the second AP with better signal, and switch from connecting with the first AP to connecting with the second AP. The above process It can be called terminal roaming.

The terminal usually enters a power save mode (English: power save mode) when there is no data to send and receive. After entering the power save mode, the terminal only turns on the radio frequency module periodically to send and receive data. When the radio frequency module of the terminal is turned off, the terminal cannot actively initiate roaming. When the terminal turns on the radio frequency module, the link between the terminal and the originally connected AP may have deteriorated to the point that it cannot communicate normally, and the terminal can only re-associate with the AP in the WLAN. When there is data buffered for the terminal, the STA will not be able to receive the data, resulting in data loss.

Contents of the invention

The present application provides a method and device for switching an access point in a wireless local area network, which are used to enable a terminal in a power saving mode to successfully switch between APs.

In a first aspect, the present application provides a method for switching APs in a WLAN. In the WLAN system to which the method is applied, each STA in an extended service set (English: extended service set, ESS) is assigned a basic service set identifier ( English: basic service set identifier, BSSID), and different STAs in the same ESS are assigned different BSSIDs, and the AP in the ESS provides services for the STAs based on the BSSIDs assigned to the STAs. After the first AP determines that the STA it is connected to is in the power-saving mode and the STA in the power-saving mode needs to switch to the second AP in the same ESS, on the one hand, it sends a wake-up frame to the STA, indicating that the STA is in the second AP. The AP is awake when sending beacon frames based on the BSSID assigned to the STA. On the other hand, the first AP sends a switching instruction to the second AP, instructing the second AP to provide services for the STA based on the BSSID allocated for the STA. After sending the wake-up frame to the STA and the switching instruction to the second AP, the first AP stops providing services for the STA.

The AP switching process of the above-mentioned STA connected to the AP is performed by the AP. Therefore, even if the STA is in the power saving mode and the radio frequency module is turned off, the AP switching of the STA can also be performed normally, ensuring that the STA turns on the radio frequency module. Can communicate through the AP in the ESS, and because the STA can switch to the AP with better connection signal, the communication quality of the STA is better

In an optional implementation, after the first AP determines that the STA is in the power-saving mode and that the STA needs to be connected to the second AP, the first AP first judges whether its own beacon frame transmission time is different from that of the second AP's beacon frame. Whether the sending time is synchronized, if the two are synchronized, the first AP may omit the step of sending a wake-up frame to the STA, and directly send a switching instruction to the second AP. When the beacon frame transmission time of the first AP is not synchronized with the beacon frame transmission time of the second AP, the first AP not only sends a wake-up frame to the STA, but also sends a switching instruction to the second AP to ensure that the STA The second AP is in an awake state when sending the beacon frame based on the BSSID allocated to the STA, so that the STA can receive the beacon frame sent by the second AP. This implementation can reduce the sending of wake-up frames when the timing of sending beacon frames by the first AP and the second AP is synchronized, saving transmission resources and reducing time-consuming AP switching.

In an optional implementation, the wake-up frame includes a first beacon frame, and the first beacon frame includes a message for instructing the STA to adjust the wake-up time to the second AP sending a beacon frame based on the BSSID allocated for the STA. time field. For example, the time stamp field included in the first beacon frame is used to instruct the STA to synchronize the local time with the time of the second AP. In this way, the wake-up time of the STA is synchronized with the sending time of the beacon frame of the second AP, so that the STA The STA can receive the beacon frame sent by the second AP to the STA based on the BSSID allocated for the STA.

In an optional implementation, before the first AP sends to the STA a wake-up frame including a field for instructing the STA to adjust the wake-up time to the time when the second AP sends a beacon frame based on the BSSID allocated for the STA, First determine the time interval between the beacon frame sending time of the first AP and the beacon frame sending time of the second AP, the method of determining the time interval may be: the first AP determines to receive the second AP sent The time of the second beacon frame; the first AP determines the beacon frame transmission time of the first AP and the beacon frame of the second AP according to its own beacon frame transmission time and the time of receiving the second beacon frame Time interval before send time. After determining the time interval, the first AP determines the field for updating the STA wake-up time according to the time interval.

In an optional implementation, the wake-up frame includes a third beacon frame, and the third beacon frame includes a field indicating that the STA remains in the wake-up state. Wherein, the STA being in the awake state may mean that the STA is in the active mode, or the STA is in the power saving mode and has entered (for example, entered according to the listening interval) the awake state. A STA in the awake state turns on its radio frequency module. For example, the data to be transmitted indication information (English: delivery traffic indication message, DTIM) field in the third beacon frame is set to 1. In some implementations, the AP and the STA agree that after the STA receives the beacon frame with the DTIM field set to 1, to switch from power saving mode to active mode. In some other implementation manners, the AP and the STA agree that after the STA receives the beacon frame in which the DTIM field is set to 1, the STA continues to be in the power saving mode, but remains in the awake state.

In an optional implementation, the STA receives the third beacon frame, the DTIM field in the third beacon frame is set to 1, the STA sends an election (English: poll) frame to the first AP, and the first AP receives the poll frame , but does not send data to the STA, the STA will remain awake until it receives data or a beacon frame sent by the connected AP.

In an optional implementation, after the first AP sends the third beacon frame indicating that the STA is in the awake state to the STA, it sends one or more data frames to the STA, and the data frames may not contain transmission An empty dataframe of data. For example, when the STA is in the wake-up state of the power saving mode, the first AP receives the poll frame sent by the STA, and sends one or more data frames to the STA, and the "More Data" field of each data frame is set to 1 , after receiving the data frame, the STA remains awake and sends a poll frame to the first AP again. For another example, when the STA is in the active mode, the first AP sends a data frame to the STA. After receiving the data frame, the STA will restart the countdown to enter the power saving mode, so that the STA can remain in the active mode.

In an optional implementation, after the first AP sends the beacon frame indicating that the STA is in the awake state, the plurality of data frames for enabling the STA to maintain the awake state sent to the STA may include an empty data frame. Even if the first AP does not cache the data frame of the STA, the first AP can also send an empty data frame to the STA, and the "More Data" field of the empty data frame is set to 1, indicating that the first AP has cached the data frame of the STA to deceive STA keeps it awake.

In an optional implementation, after confirming that the connection with the STA is successful, the second AP sends a handover success message to the first AP, and the first AP stops sending the wake-up frame for the STA after receiving the handover success message.

In a second aspect, the present application provides a device for switching APs in a WLAN, and the device is configured to execute the method in the above first aspect or any possible implementation of the first aspect. Specifically, the device includes a module for performing the method in the foregoing first aspect or any possible implementation of the first aspect.

In a third aspect, the present application provides a device for switching APs in a WLAN, and the device is configured to execute the method in the first aspect or any possible implementation of the first aspect. Specifically, the device includes a processor and a transceiver, and the processor is coupled with the transceiver. The transceiver is used to communicate with other network elements in the WLAN, and the processor is used to execute the method in the above first aspect or any possible implementation of the first aspect through the transceiver.

In a fourth aspect, the present application provides a computer-readable medium for storing a computer program, and the computer program includes instructions for executing the method in the first aspect or any possible implementation of the first aspect.

On the basis of the implementations provided by the above aspects, the present invention can be further combined to provide more implementations.

Description of drawings

In order to illustrate the technical solutions in this application more clearly, the accompanying drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. Ordinary technicians can also obtain other drawings based on these drawings without paying creative labor.

FIG. 1 is a schematic diagram of a possible implementation of a communication system in an embodiment of the present invention;

FIG. 2 is a schematic flowchart of a method for switching APs in an embodiment of the present invention;

FIG. 3 is another schematic flowchart of a method for switching APs in an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a device for switching APs in a WLAN according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a device for switching APs in another WLAN according to an embodiment of the present invention.

detailed description

The technical solutions of the present invention will be described in detail below with reference to the drawings and specific embodiments. The embodiments of the present invention and specific features in the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations to the technical solutions of the present invention. In the case of no conflict, the embodiments of the present invention and the technical features in the embodiments may be combined with each other.

In WLAN communication, a STA needs to be connected to an AP, and the connected AP is responsible for data forwarding for the STA. When the signal between the STA and the currently connected AP is poor, the STA needs to switch to an AP with better signal to ensure normal data communication of the STA. Usually, after the STA detects that the link with the AP has degraded to a certain extent, it initiates roaming and performs AP handover.

However, after the STA enters the power saving mode, the STA turns off the radio frequency module and only turns on the radio frequency module periodically to send and receive data. When the STA's radio module is turned off, the STA cannot actively initiate roaming. However, when the STA turns on the radio frequency module, the link between the STA and the originally connected AP may have deteriorated to the point that it cannot communicate normally, and the STA can only re-associate with the AP in the WLAN. When the STA caches data, the STA will not be able to receive the data, resulting in data loss.

In order to solve the problem that it is difficult for a STA in power-saving mode to switch between APs, an embodiment of the present invention provides an AP switching method. When the STA is in power-saving mode, the AP is responsible for switching the AP to which the STA is connected. When the STA turns off the radio module, the handover of the AP connected to the STA can still be completed.

In the embodiment of the present invention, when a STA associates with an AP in an extended service set (English: extended serviceset, ESS) for the first time, the STA will be assigned a basic service set identifier (English: basicservice set identifier, BSSID). Any AP connected to the STA provides services for the STA based on the BSSID. That is, the AP in the ESS emulates the AP with the BSSID assigned to the STA as the BSSID, and sends and receives frames of the STA. That is to say, when the AP in the ESS communicates with the STA, the BSSID is used as the radio frequency medium access control (English: media access control, MAC) address of the AP. Since different APs provide services for STAs based on the same BSSID, after the AP connected to the STA switches, the STA will not perceive the AP switching. On the other hand, the BSSIDs allocated to any two STAs in the ESS are different, which can avoid packet forwarding confusion after the STAs perform AP handover in the ESS.

Wherein, the allocation manner of the BSSID corresponding to the STA includes multiple implementation manners. For example, after a STA initiates an association request to an AP in the ESS, the AP that receives the STA association request allocates a BSSID for the STA, and notifies the other APs of the ESS of the BSSID, so that when the STA is connected to other APs in the ESS , the AP to which the STA is connected can provide services for the STA based on the BSSID allocated for the STA. For another example, in the communication system shown in FIG. 1, after the STA initiates an association request to the AP in the ESS, the roaming controller in the WLAN allocates a BSSID for the STA, and notifies the AP in the ESS that based on the BSSID allocated for the STA, Provide services for the STA.

In the embodiment of the present invention, when the WLAN includes the above-mentioned roaming controller, the roaming controller can be implemented in multiple ways, for example, the roaming controller can be used as the control and specification of the wireless access point (English: Control And Provisioning of Wireless Access Points , CAPWAP) protocol access controller (English: Access Controller, AC), correspondingly, the AP can be used as a wireless termination point (English: Wireless Termination Point) in the CAPWAP protocol. In addition, the roaming controller can be implemented by an independent device, or by a cluster of multiple distributed devices.

In the embodiment of the present invention, after the STA reaches the roaming threshold, the AP connected to the STA switches the STA to another AP in the same ESS. It is called a target AP, indicating that the target AP provides services for the STA based on the BSSID allocated for the STA.

The AP to which the STA is connected may determine whether the STA has reached the roaming threshold, or the roaming controller shown in FIG. 1 may determine whether the STA has reached the roaming threshold. Specifically, the AP connected to the STA monitors the signal indicators of the STA, for example, received signal strength indication (English: received signal strength indication, RSSI), packet loss rate, and so on. When the monitoring value of the signal index of the STA by the AP connected to the STA deteriorates to a preset value, it can be determined that the STA has reached the roaming threshold. When the roaming controller judges whether the STA has reached the roaming threshold, the AP to which the STA is connected needs to send the monitoring value of the signal index of the STA to the roaming controller.

The way to determine the target AP that the STA needs to connect to can be as follows: APs that are not connected to the STA in the same ESS monitor the signal indicators of the STA, and the APs connected to the STA or the roaming controller use these APs that are not connected to the STA to The target AP is determined from the APs not connected to the STA based on the monitoring value of the signal index of the STA. For example, the AP not connected to the STA in the same ESS will send the monitoring value of the signal index of the STA to the AP or roaming controller connected to the STA, and the AP or roaming controller connected to the STA will determine the detected signal index The best AP is used as the target AP.

Usually, after the STA sends a message to the connected AP, the physical layer of other APs that are not connected to the STA can also receive the message and calculate signal indicators such as RSSI. Then, the AP’s media access control (English: The media access control (MAC) layer will judge whether the message is sent to itself, and if the message is not sent to itself, the message will be discarded. However, in the embodiment of the present invention, after the MAC layer determines that the message is not sent to itself, the signal indicators such as the RSSI of the message are still stored in the memory, so that the AP can obtain the signal indicators of STAs that are not connected to itself. . The AP may also use other technical means in the prior art to monitor the signal indicators of STAs not connected to itself, which will not be described in detail in the embodiment of the present invention.

Usually, the times at which different APs send beacon frames are not synchronized. For example, different APs have different beacon intervals. For example, one AP sends beacon frames at 0 milliseconds (ms), 100ms, 200ms... and another AP sends beacon frames at 0ms, 110ms, 220ms.... Alternatively, although the beacon intervals of different APs are the same, the phases at which the beacon frames are transmitted are different. For example, one AP sends beacon frames at 0ms, 100ms, 200ms... and another AP sends beacon frames at 30ms, 130ms, 230ms.... When the STA is in the active (English: active) mode, the STA is always in the awake state (English: awake state), the STA can receive the beacon frame sent by the second AP after switching, and send the beacon frame according to the second AP A field for synchronizing time included in , to synchronize its own time with the time of the second AP.

When the STA is in the power saving mode, the STA is in a doze state (English: doze state), and only enters a wake-up state according to a listening interval (English: listen interval) to receive selected beacon frames. The listening interval is generally an integer multiple of the beacon interval. Therefore, the STA turns on the radio frequency module and receives the beacon frame only at the time when the first AP sends the beacon frame before the handover. However, since the beacon frames sent by the first AP and the second AP are usually not synchronized, the STA in the power saving mode may not receive the beacon frame sent by the second AP within a short period of time when it enters the wake-up state, causing the STA to It cannot synchronize its own local time with the time of the switched second AP according to the beacon frame sent by the second AP. In this way, although the second AP has taken over from the first AP to provide services for the STA, since the STA cannot receive the beacon frame sent by the second AP, it cannot synchronize the local time with the time of the second AP, and thus cannot pass the second AP. Send and receive data.

In order to solve this problem, an embodiment of the present invention provides a method for switching APs in a WLAN and an AP. The first AP before the switch sends a wake-up frame to the STA, so that the STA sends a beacon frame at the second AP after the switch. It can be in an awake state, so that the STA can receive the beacon frame sent by the second AP, and synchronize the local time with the time of the second AP according to the beacon frame sent by the second AP.

In conjunction with FIG. 2, the following takes the first AP switching the first STA connected to it to the second AP as an example to describe in detail the method for switching the AP provided by the embodiment of the present invention. The method for switching the AP includes the following steps:

Step 101: the first AP determines that a first STA connected to the first AP is in a power saving mode, and determines that a second AP in the ESS where the first AP is located is a target AP to which the first STA needs to connect.

Specifically, the first AP is connected to the first STA, which means that the first STA is connected to the WLAN through the first AP, and the first AP provides services for the first STA, for example, the first AP forwards data for the first STA; For another example, when the first STA enters the power saving mode, the first STA caches data for the first STA.

The first STA can be any STA connected to the first STA. When the first STA enters the power saving mode, it will send a record of the first STA entering the power saving mode to the connected first AP. This record can determine that the first STA enters the power saving mode.

In step 101, the first AP can learn the roaming threshold of the first AP according to the method described above, and learn that the second AP in the same ESS is the target AP that the first AP needs to connect to. The embodiment of the present invention will not be repeated here.

Step 102: The first AP sends a wake-up frame to the first STA, where the wake-up frame is used to indicate that the first STA is in an awake state when the second AP sends a beacon frame to the first STA based on the first BSSID allocated for the first STA.

Wherein, the STA being in the awake state may mean that the STA is in the active mode, or the STA is in the power saving mode and has entered (for example, entered according to the listening interval) the awake state. A STA in the awake state turns on its radio frequency module.

The wake-up frame in step 102 can have multiple implementations, including but not limited to any of the following implementations:

Mode 1, the wake-up frame is a beacon frame, and the beacon frame includes a field for updating the wake-up time of the first STA, and the field for updating the wake-up time of the first STA is used to instruct the first STA to adjust the wake-up time to the second The time at which the AP sends the beacon frame based on the first BSSID.

Usually, the beacon frame sent by the first AP to the first STA based on the first BSSID includes a field for instructing the first STA to synchronize the wake-up time with the time when the first AP sends the beacon frame. However, in this embodiment of the present invention, in order to ensure that the first STA can receive the beacon frame sent by the second AP, the first AP may update the wake-up time of the first STA in the beacon frame sent to the first STA. The modified field is used to instruct the first STA to synchronize the wake-up time with the time when the second AP sends the beacon frame. This includes instructing the first STA to adjust the wake-up time to the second AP based on the first BSSID. The beacon frame in the time field of sending the beacon frame can be used as the wake-up frame in the embodiment of the present invention.

Wherein, the first AP needs to determine the difference between its own beacon frame transmission time and the second AP's beacon frame transmission time, and then it can determine that the instruction includes instructing the first STA to adjust the wake-up time to the second AP based on the first BSSID. Field for the time at which the beacon frame was sent. Since the first AP is adjacent to the second AP, the first AP can receive the beacon frame sent by the second AP. The beacon frame can be a traditional beacon frame, that is, the second AP sends based on the BSSID of the second AP itself. beacon frame. The first AP determines the local time of the first AP when receiving the beacon frame of the second AP, and calculates the time difference (T_offset ), and then determine the value of the field for updating the wake-up time of the first STA according to the time difference. If the period in which the second AP sends the beacon frame is different from the period in which the first AP sends the beacon frame, the difference between the periods in which the two APs send the beacon frame may also be considered when calculating the time difference. Optionally, the calculation of the above time difference may also take into account the delay between the time when the first AP receives the beacon frame sent by the second AP and the time when the second AP actually sends the beacon frame.

For example, the timestamp (English: timestamp) field in the beacon frame is the field used to update the STA wake-up time, and the timestamp field is used to synchronize the local time of the STA with the time of the AP. If the first STA does not need to switch APs, the value of the timestamp field of the beacon frame sent by the first AP to the first STA at time T1 is A; and if the first STA needs to be switched to the second AP The value of the timestamp field of the beacon frame sent by the first AP to the first STA at time T1 is adjusted to (A-T_offset). In this way, after the first STA performs time synchronization according to (A-T_offset), although it will cause the first STA to A STA is not synchronized with the time of the first AP, but the next wake-up time of the first STA can be synchronized with the time when the second AP sends a beacon frame.

For another example, the field used to update the STA wake-up time in the beacon frame may also be a beacon interval (English: beacon interval) or a listening interval field. Wherein, the beacon interval field is the interval at which the AP sends the beacon frame, and the listening interval field is an integer multiple of the beacon interval field, indicating the interval at which the STA receives the beacon frame. If the first STA does not need to switch APs, the value of the beacon interval field in the beacon frame sent by the first AP to the first STA at time T1 is B, and the value of the listening interval field is k*B, where k is a positive integer ; and in the case that the first STA needs to be handed over to the second AP, the value of the beacon interval field of the beacon frame sent by the first AP to the first STA at time T1 is (B-D), and the value of the listening interval field is k*(B-D), wherein, k*D=T_offset, in this way, the first STA enters the next wake-up time after k*(B-D) according to the listening interval l field, and this time happens to be when the second AP sends a beacon frame time.

Through the above method 1, after the first AP determines to switch the first STA to the second AP, it sends a beacon frame to the first STA, and the field used to update the wake-up time of the first STA in the beacon frame is directed to the second AP to send a beacon frame. The time when the beacon frame is sent, not the time when the first AP sends the beacon frame. In this way, after the first STA receives the beacon frame, the subsequent wake-up time is adjusted to a time synchronized with the beacon frame sent by the second AP, so that the first STA can receive the beacon frame sent by the second AP.

It should be noted that in mode 1, the wake-up time of the first STA is synchronized with the beacon frame sending time of the second AP, which means that the set of wake-up time of the first STA is a subset of the set of beacon frame sending times of the second AP. Sets, two sets can be equal, but not necessarily equal.

Mode 2, the wake-up frame includes a beacon frame, and the beacon frame includes a field indicating that the first STA remains in the wake-up state in the power saving mode.

Usually, the first STA in the power-saving mode enters the awake state from the sleepy state, and receives the beacon frame sent by the connected first AP. If the beacon frame does not include the field for keeping the first STA in the awake state, the first STA The STA switches from the awake state back to the doze state. If the beacon frame includes the field for keeping the first STA in the awake state, the first STA remains in the awake state after receiving the beacon frame.

For example, the field for waking up the first STA in the beacon frame may be a data delivery traffic indication message (English: delivery traffic indication message, DTIM) field.

Usually, after buffering the data frame or management frame for the connected first STA, the first AP will set the bit corresponding to the first STA to 1 in the DTIM field of the beacon frame sent to the first STA, and inform the first STA that there is a possibility to The cache unit (English: bufferable unit, BU) needs to be acquired. The first STA in the power saving mode turns on the radio frequency module during the wake-up time, receives the beacon frame, and keeps the wake-up state according to the DTIM field in the beacon frame. And send an election (poll) frame to the first AP, and after receiving the poll frame, the first AP sends the data packet buffered by the first STA to the first STA.

However, in the embodiment of the present invention, when the first STA in the power-saving mode needs to be switched to the second AP, even if the first AP does not buffer data frames or management frames for the first STA, the first AP is still sending the first STA A field that keeps the first STA awake (for example, a DTIM field that sets the bit number corresponding to the first STA to 1) is added to the sent beacon frame to keep the first AP awake so that it can receive the second AP. Beacon frames sent by the AP.

Optionally, after the first STA receives the third beacon frame sent by the first AP, it sends a poll frame to the first AP, and after the first AP receives the poll frame, it does not send the bufferable unit BU to the first STA. . Since the first STA cannot receive the bufferable unit sent for the poll frame, the first STA will remain awake until it receives the bufferable unit sent by the first AP for the poll frame, or until the signal from the first STA The arrival of the frame sending time.

Mode 3 is different from the foregoing mode 2 in that the beacon frame sent by the first AP to the first STA includes a field indicating that the first STA switches from the power saving mode to the active mode.

During specific implementation, there are the following two situations between mode 2 and mode 3:

In case 1, in mode 2, the beacon frame sent by the first AP to the first STA includes field A, which is used to indicate that the first STA remains awake; while in mode 3, the beacon frame sent by the first AP to the first STA The beacon frame includes a field B, and the field B is used to instruct the first STA to switch from the power saving mode to the active mode. Wherein, field A and field B are two different fields.

Case 2, the beacon frame sent by the first AP to the first STA in method 2 includes field A. In the application scenario of method 2, the first AP and the first STA agree that the field A is used to indicate the first STA remains awake. In mode 3, the beacon frame sent by the first AP to the first STA also includes field A, but in the application scenario of mode 3, the first AP and the first STA agree that this field A is used to indicate the first STA Switch from power saving mode to active mode. For example, in one possible implementation, the first STA does not exit the power saving mode and remains awake after receiving a beacon frame with DTMI bit 1; while in another possible implementation, the first STA receives After the beacon frame with DTMI bit 1, send the record of exiting the power saving mode to the connected AP, exit the power saving mode, and enter the active mode.

It should be noted that, regardless of whether the first STA remains awake without exiting the power saving mode in mode 2, or the first STA switches from the power saving mode to the active mode in mode 3, the radio frequency module of the first STA Both are in the working state, and can receive the beacon frame sent by the second AP based on the first BSSID.

Method 4, combined with method 2, after the first AP sends to the first STA a beacon frame indicating that the first STA remains awake, at least one data frame is sent to the first STA, and the data frame includes instructions to the first STA to continue Field to keep awake.

In the embodiment of the present invention, the so-called data frame may be a data frame containing transmission data, or an empty data frame not containing transmission data.

Specifically, after the first STA receives the above-mentioned third beacon frame sent by the first AP, it sends a poll frame to the first AP, and after the first AP receives the poll frame, it sends at least one data frame (including empty frames) to the first STA. data frame), wherein the "More Data" field of each frame in at least one data frame is set to 1, indicating that the first STA continues to maintain the awake state and continues to send poll frames to the first AP, while the first AP continues to Set the "More Data" field to 1 in the data frame sent to the first STA. In this way, the first STA will remain awake until the first AP does not set the "More Data" field in the data frame sent to the first STA to 1.

Way 5, combined with way 3, after the first AP sends to the first STA a beacon frame indicating that the first STA switches from the power saving mode to the active mode, then sends at least one data frame to the first STA.

After the first STA switches from the power saving mode to the active mode, it may stay in the active mode for a period of time, and the time period may be determined through negotiation between the first STA, the first AP, or both. If the duration of keeping the active mode is short, the first STA may switch from the active mode back to the power saving mode before the beacon frame transmission time of the second AP arrives, resulting in the first STA being unable to receive the second AP based on the first Beacon frame sent by BSSID.

In order to solve this problem, in the embodiment of the present invention, after the first AP sends a beacon frame to the first STA to instruct the first STA to switch from the power-saving mode to the active mode, the first AP also sends a message or Multiple data frames (including the case of an empty data frame). After the first STA receives each data frame, it will remain in the active mode for a period of time. Therefore, if the data frames are sent continuously, the first STA will always remain in the active mode.

For example, it is assumed that the power saving policy of the first STA is set to: if the first STA does not transmit and receive data for a period of time S in the active mode, then switch from the active mode to the power saving mode. The first STA receives the beacon frame sent by the first AP at time T1 and includes a field used to instruct the first STA to switch from the power saving mode to the active mode, and switches from the power saving mode to the active mode. If the first STA does not To send and receive data, it will enter the power saving mode again at (T1+S) time. In order to avoid this situation, in the embodiment of the present invention, the first AP sends an empty data frame to the first STA at the time (T1+S-m) before the time (T1+S), and the first STA receives the empty data frame After a frame, it will remain in active mode for the time period from (T1+S-m) to (T1+2S-m). By analogy, before the active mode of the first STA ends, the first AP sends an empty data frame (or a data frame including transmission data) to the first STA again, so that the first STA remains in the active mode.

In the above method 4 and method 5, the first AP keeps the first STA in an awake state by sending multiple data frames to the first STA after sending the third beacon frame to the first STA, so that the first STA can A beacon frame sent by the second AP is received.

It should be noted that, if there is no conflict, any two or more of the above methods 1 to 5 can be used in combination. The time-synchronized beacon frame sends multiple empty data frames to the first STA, and the "More Data" field in these empty data frames is set to 1, indicating that the first STA remains awake.

In addition, in the above method 1, the wake-up time of the first STA is synchronized with the beacon frame transmission time of the second AP, which means that the set of wake-up time of the first STA is a subset of the beacon frame transmission time set of the second AP, Two sets can be equal, but they don't have to be.

Step 103: the first AP sends a switching instruction to the second AP, where the switching instruction is used to instruct the second AP to provide services for the first STA based on the first BSSID.

Specifically, the handover instruction includes the identifier of the first STA, and is used to instruct the second AP to provide services for the first STA. Optionally, if the first AP or the roaming controller does not immediately inform the second AP of the mapping between the first STA and the first BSSID after allocating the first BSSID to the first STA, the first AP sends a The handover instruction may further include the first BSSID allocated for the first STA, so that the second AP can provide services for the first STA based on the first BSSID.

Step 104: the first STA receives the wake-up frame, and keeps awake at the time when the beacon frame of the second AP is sent.

In step 104, the specific implementation manner of keeping the second AP in the awake state according to the wake-up frame at the beacon frame sending time of the second AP has been described in step 102 and will not be repeated here. In addition, in step 104, the first STA keeps awake at the beacon frame sending time of the second AP. state.

Step 105: The second AP receives the handover instruction, and provides service for the first STA based on the first BSSID allocated for the first STA.

Specifically, after receiving the switching instruction, the second AP is responsible for providing services for the first STA. The so-called service provision includes: the second AP sends a beacon frame to the first STA based on the first BSSID, so that the first STA maintains a link with the second AP according to the beacon frame.

Wherein, the second AP obtains the mapping between the first STA and the first BSSID, which may be implemented in the following manner: after the roaming controller allocates the first BSSID to the first STA, it sends the mapping between the first STA and the first BSSID to the ESS For each AP of , the second AP can then learn the first BSSID assigned by the roaming controller to the first STA. Alternatively, after receiving the switching instruction sent by the first AP, the second AP requests the roaming controller to send the BSSID corresponding to the first STA to the second AP, and the second AP can then learn the first BSSID. Alternatively, when sending the switching instruction to the second AP, the first AP also sends the first BSSID corresponding to the first STA to the second AP.

Step 106: the first AP stops providing services for the first STA.

Specifically, the first AP stops providing services for the first STA, which means that the first AP no longer regards the first STA as an STA that needs to provide normal WLAN services, for example, no longer sends information based on its BSSID for the first STA. frame, forward data, buffer data, and so on.

In combination with any of the ways 2 to 5 in the various implementations of the aforementioned step 102, the first AP may continue to send a wake-up frame to the first STA after performing steps 102 and 103, indicating that the first STA Stay awake during the beacon frame sending time of the second AP. In the above behavior of the first AP sending a wake-up frame to the first STA, the first AP does not provide normal WLAN services to the first STA. Therefore, the so-called first AP stops providing services for the first STA in step 106, which is different from the above-mentioned first AP. After performing step 102 and step 103, the AP continues to send wake-up frames to the first STA without conflict.

In addition, the IP address used by the STA does not change before and after the AP switching. From the point of view of the STA, the BSSID of the AP it is connected to remains unchanged, and it still uses the same IP address for data transmission and reception. Therefore, in the embodiment of the present invention, the STA does not perceive that the AP has been switched at all.

In the above technical solution of the embodiment of the present invention, the first STA in the ESS is assigned a unique first BSSID, and the AP connected to the first STA in the ESS provides services for the first STA based on the first BSSID. When the first AP determines that the connected first STA has reached the roaming threshold and the first STA is in the power saving mode, on the one hand, it sends a switching instruction to the second AP that the first STA needs to connect to, indicating that the second AP is based on the first BSSID as The first STA provides services; on the other hand, the first AP sends a wake-up frame to the first STA, instructing the first STA to keep awake at the beacon frame sending time of the second AP, so that the first STA can receive the second AP The sent beacon frame can maintain the link with the second AP according to the beacon frame sent by the second AP, so as to ensure that the first STA can accept the service provided by the second AP. The above-mentioned STA connection AP switching process is performed by the AP side. Therefore, even if the first STA is in the power saving mode and the radio frequency module is turned off, the AP switching of the first STA can also be performed normally, ensuring that the first STA is turned on. After the radio frequency module, it can communicate through the AP in the ESS, and because the first STA can switch and connect to the AP with better signal, the communication quality of the first STA is better.

Not only that, when the first AP has buffered data for the first STA, the first AP will also hand over the data buffered for the first STA to the second AP, and the second AP will send the buffered data to the first STA, avoiding data lost.

In a possible implementation, referring to FIG. 3 , the following steps are also included before step 102:

Step 107: The first AP judges whether the beacon frame transmission time of itself is synchronized with the beacon frame transmission time of the second AP, if so, then skip step 102, and directly execute step 103, if not, then execute step 102, Step 103 is also executed.

Specifically, after the first AP determines that the first STA needs to be handed over to the second AP, it first judges whether the time when the second AP and the first AP send beacon frames are synchronized. The first STA of the beacon frame itself can receive the beacon frame sent by the second AP, and the first AP may directly perform step 103 without performing step 102 .

If the time when the second AP sends the beacon frame is not synchronized with the time when the first AP sends the beacon frame, the first AP executes step 102 so that the wake-up time of the first STA is the time when the second AP sends the beacon frame.

In the above technical solution, the first AP judges whether the time when the first AP and the second AP send beacon frames are synchronized. When the two are not synchronized, the wake-up frame is sent to the first STA, which can not only ensure that the first STA can receive the beacon frame sent by the second AP, but also can transmit the beacon frame between the first AP and the second AP. During time synchronization, the sending of wake-up frames is reduced to save transmission resources.

In another possible implementation, after determining that the connection with the first STA is successful, the second AP sends a handover success message to the first AP, so that the first STA knows that the first STA has successfully handed over to the second AP, and After receiving the handover success message, the second AP may stop sending the wake-up frame in step 102 to the first STA.

Wherein, the manner in which the second AP determines that the connection with the first STA is successful includes:

In mode A, the second AP sends a frame to the first STA that requires the first STA to return a message, and the first STA returns a message to the second AP. After receiving the return message, the second AP can determine that the connection with the first STA has been successful. establish connection.

The frame that requires the first STA to return a message can be implemented in multiple ways. For example, the frame is a data frame, and the first STA returns an ACK frame to the second AP after receiving the data frame sent by the second AP. Since the ACK frame sent by the first STA to the second AP includes the identity of the second AP, and the second AP provides services for the first STA based on the first BSSID, and the second AP uses the first STA only when it provides services for the first STA. A BSSID is used as its own BSSID. Therefore, the second AP can determine that the ACK frame is sent by the first STA according to receiving the first BSSID in the ACK frame, and then determine that the connection with the first STA has been successfully established.

Optionally, since the first STA will remain awake for a short period of time after receiving the beacon frame sent by the second AP, the second AP may, within the short period of time after sending the beacon frame to the first STA, The frame for determining whether the second AP determines whether the connection with the first STA is successful is sent to the first STA internally, so that the first STA can receive the frame and return a message according to the frame.

In mode B, the first STA in the power saving mode may actively send packets to the connected AP, and after receiving these packets, the second AP can determine that the connection with the first STA is successfully established.

For example, when the first STA turns off the power saving mode, it will send a record of turning off the power saving mode to the connected AP, and the second AP can determine that the connection with the first STA is successfully established after receiving the message containing the record.

In the above technical solution, the second AP can determine to establish a connection with the first STA according to the received message sent by the first STA, and send a handover success message to the first AP, so that the first STA knows that the first STA has successfully switched to Second AP. The first AP can send a wake-up frame to the first STA before receiving the handover success message to ensure that the first STA can receive the beacon frame sent by the second AP, and after the first AP receives the wake-up frame, stop sending the beacon frame to the first STA. Sending the wake-up frame by the first STA can not only save transmission resources, but also avoid confusion of the first STA's response.

The embodiment of the present invention also provides a device 200 for switching APs, and the device 200 serves as an AP in a WLAN. FIG. 4 is a schematic structural diagram of a device 200 , and the device 200 includes: a processor 201 and a transceiver 202 .

Wherein, the processor 201 is configured to: determine that the STA connected to the device 200 is in the power-saving mode, wherein the device 200 provides services for the STA based on the BSSID corresponding to the STA, and the BSSID corresponding to the STA and the The BSSID corresponding to any other STA in the same ESS of the STA is different; determine the second AP in the ESS as the target AP, and the target AP is the AP connected to the STA after switching; generate a wake-up frame, the The wake-up frame is used to indicate that the STA is in an awake state when the second AP sends a beacon frame based on the BSSID corresponding to the STA; a switching instruction is generated, and the switching instruction is used to instruct the second AP to send a beacon frame based on the BSSID corresponding to the STA. The BSSID corresponding to the STA provides services for the STA;

The transceiver 202, coupled to the processor 201, is configured to: send the wake-up frame to the STA; and send the switching instruction to the second AP.

In the embodiment of the present invention, the processor 201 and the transceiver 202 may be two separate components connected through a bus; in addition, the processor 201 and the transceiver 202 may also be integrated, which is not limited in this embodiment of the present invention.

The processor 201 may be one processing element, or may be a general term for multiple processing elements. For example, the processor may be a central processing unit (English: central processing unit, CPU), or a specific integrated circuit (English: application specific integrated circuit, ASIC), or be configured to implement one or more of the embodiments of the present invention an integrated circuit.

The transceiver 202 includes an antenna and a radio frequency module connected to the antenna. Optionally, when the device 200 communicates with the second AP through a wired network such as an optical fiber network, the transceiver 202 includes, in addition to the above-mentioned radio frequency module and antenna, a data transceiver of a wired communication type, such as an Ethernet data transceiver .

In a possible implementation, before the processor 201 is used to: generate the wake-up frame, it is further configured to: determine that the sending time of the beacon frame of the device 200 is not synchronized with the sending time of the beacon frame of the second AP.

In a possible implementation, the wake-up frame includes a first beacon frame, the first beacon frame includes a field for updating the STA wake-up time, and the field for updating the STA wake-up time It is used to instruct the STA to adjust the wake-up time to the time when the second AP sends a beacon frame based on the BSSID corresponding to the STA.

In a possible implementation, the transceiver 202 is further configured to: receive a second beacon frame sent by the second AP;

The processor 201 is further configured to: determine the time when the transceiver receives the second beacon frame, and according to the beacon frame sending time of the device 200 and the transceiver receiving the second beacon frame Determine the time interval between the beacon frame sending time of the device 200 and the beacon frame sending time of the second AP; and determine the field for updating the STA wake-up time according to the time interval.

In a possible implementation, the wake-up frame includes a third beacon frame, and the third beacon frame includes a field indicating that the STA remains in the wake-up state.

In a possible implementation, the wake-up frame further includes: at least one data frame sent after the third beacon frame, where the at least one data frame is used to keep the STA in a wake-up state.

In a possible implementation, the at least one data frame includes an empty data frame.

In a possible implementation, the device 200 further includes a memory 203, which can be used to: store data sent by connected STAs, store data sent to STAs by other network elements, and store state records of STAs (such as whether they are in a provincial state or not). power mode), store instructions sent to the device 200 by other network elements, and so on.

Optionally, the memory 203 may also store executable instructions, and the processor 201 reads and executes the executable instructions in the memory 203 to implement the functions of the device 200 in the embodiment of the present invention.

The above-mentioned memory 203 may be one storage element, or may be a general term for multiple storage elements, and is used to store executable program codes or parameters and data required for device operation. In addition, the above-mentioned memory 203 may include a random-access memory (English: random-access memory, RAM), or may include a non-volatile memory (English: non-volatile memory, NVM), and so on.

It should be noted that the memory 203 and the Ethernet data transceiver in FIG. 4 are represented by dotted boxes, indicating that they are not necessary modules for the AP to realize its functions in the embodiment of the present invention. Generally, the AP also has functions other than those described in the embodiments of the present invention, and these functions need to be implemented based on the memory 203 and/or the Ethernet data transceiver.

For specific implementation manners of operations performed by the constituent modules included in the above device 200, reference may be made to the corresponding steps performed by the first AP in the embodiments corresponding to FIG. 2 and FIG. 3 , and details are not repeated in this embodiment of the present invention.

The embodiment of the present invention also provides a device for switching APs, which can be used as an AP in a WLAN. The device includes: a processor and a transceiver.

Wherein, the transceiver is used to receive the handover command sent by the first AP, and the handover command includes the identity of the first STA.

The processor, coupled with the transceiver, is configured to: control the AP to provide a service for the first STA based on the first BSSID generated for the first STA.

In a possible implementation, the transceiver is further configured to: receive any message sent by the first STA;

The processor is further configured to: after the transceiver receives any message sent by the first STA, generate a handover success message;

The transceiver is also used for: sending a handover success message to the first STA.

In a possible implementation, the processor is further configured to: after the transceiver receives the switching instruction, generate a frame that requires the first STA to return a message;

The transceiver is further configured to: send the frame requiring the first STA to return a message to the first AP.

For the specific implementation manner of the operations performed by the constituent modules included in the above AP, reference may be made to the corresponding steps performed by the second AP in the embodiment corresponding to FIG. 2 , which will not be repeated in this embodiment of the present invention.

An embodiment of the present invention also provides a communication system, which includes multiple APs and multiple STAs.

Wherein, the first AP among the multiple APs is used to: determine that the first STA connected to the first AP is in the power saving mode, and determine that the first STA needs to switch to connect with the second AP in the same ESS; The STA sends a wake-up frame, and the wake-up frame is used to make the first STA wake up at the time when the second AP sends a beacon frame; and sends a switching instruction to the second AP, and the switching instruction is used to make the second AP assign the first STA based on the The first BSSID provides services for the first STA;

The first STA among the plurality of STAs is used to: receive the wake-up frame, and keep awake at the time when the second AP sends the beacon frame according to the wake-up frame;

The second AP among the multiple APs is configured to: receive a handover instruction sent by the first AP, where the handover instruction includes the identifier of the first STA; and provide services for the first STA based on the first BSSID.

In a possible implementation, before sending the wake-up frame to the STA, the first AP determines that its own beacon frame sending time is not synchronized with the second AP's beacon frame sending time.

In a possible implementation, the wake-up frame includes a first beacon frame, and the first beacon frame includes a field for updating the wake-up time of the first STA, and the field is used to indicate that the first STA will wake up The time is adjusted to the time when the second AP sends a beacon frame based on the first BSSID corresponding to the first STA.

In a possible implementation, before sending the wake-up frame to the first STA, the first AP determines the time of receiving the second beacon frame sent by the second AP; The time of the second beacon frame sent by the second AP determines the time interval between the beacon frame sending time of the first AP and the beacon frame sending time of the second AP; Update the field of the wake-up time of the first STA.

In a possible implementation, the wake-up frame further includes: at least one data frame sent after the third beacon frame, where the at least one data frame is used to keep the first STA in a wake-up state.

In a possible implementation, the at least one data frame includes an empty data frame.

In a possible implementation, the second AP is further configured to: send a handover success message to the first STA after receiving any message sent by the first STA;

The first AP is further configured to: receive a handover success message, and stop sending wake-up frames to the first STA.

In a possible implementation, the communication system further includes a roaming controller, configured to assign a unique BSSID to each STA in the same ESS, so that the AP connected to each STA provides services for the STA based on the BSSID assigned to the STA .

In a possible implementation, the first AP and the second AP are further configured to: report the monitoring value of the signal index of the first STA to the roaming controller;

The roaming controller is also used to: determine that the first STA has reached the roaming threshold according to the monitoring value, and determine that the second AP is the target AP, and send a switching trigger instruction to the first AP;

The first AP is used to: determine that the first STA has reached the roaming threshold, and determine the second AP as the target AP, including: receiving a handover trigger instruction, and determining that the first STA has reached the roaming threshold according to the handover trigger instruction, and determining the second AP as the target AP.

For specific implementation manners of operations performed by each device included in the above system, reference may be made to corresponding steps in the embodiments corresponding to FIG. 2 and FIG. 3 , and details are not repeated in this embodiment of the present invention.

The embodiment of the present invention also provides a device for switching APs in a WLAN, where the WLAN includes multiple APs and multiple STAs. With reference to Fig. 5, described device comprises:

The first determining module 301 is configured to determine that the STA connected to the device is in the power saving mode, wherein the device provides services for the STA based on the BSSID corresponding to the STA, and the BSSID corresponding to the STA is equal to and The BSSID corresponding to any other STA in the same ESS of the STA is different;

The second determination module 302 is configured to determine that the second AP in the ESS is a target AP, and the target AP is the AP connected to the STA after handover;

The first sending module 303 is configured to send a wake-up frame to the STA, where the wake-up frame is used to indicate that the STA is in an awake state when the second AP sends a beacon frame based on the BSSID corresponding to the STA;

The second sending module 304 is configured to send a switching instruction to the second AP, where the switching instruction is used to instruct the second AP to provide services for the STA based on the BSSID corresponding to the STA;

The stop service module 305 is configured to stop providing services for the STA after the second sending module sends the switching instruction.

In a possible implementation, the wake-up frame includes a first beacon frame, the first beacon frame includes a field for updating the STA wake-up time, and the field for updating the STA wake-up time It is used to instruct the STA to adjust the wake-up time to the time when the second AP sends a beacon frame based on the BSSID corresponding to the STA.

In a possible implementation, the device also includes:

The third determining module 306 is configured to determine the time at which the second beacon frame sent by the second AP is received before the first sending module sends the wake-up frame; and according to its own beacon frame sending time and The time at which the second beacon frame is received determines the time interval between the beacon frame sending time of the device and the beacon frame sending time of the second AP; and determining the user according to the time interval to update the field of the wake-up time of the STA.

In a possible implementation, the wake-up frame includes a third beacon frame, and the third beacon frame includes a field indicating that the STA remains in the wake-up state.

In a possible implementation, the wake-up frame further includes: at least one data frame sent after the third beacon frame, where the at least one data frame is used to keep the STA in a wake-up state.

In a possible implementation, the at least one data frame includes an empty data frame.

For a specific implementation manner of operations performed by each component module included in the above device, reference may be made to the corresponding steps performed by the first AP in the embodiments corresponding to FIG. 2 and FIG. 3 , and details will not be repeated in this embodiment of the present invention.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the invention may take the form of a computer program product embodied on one or more computer-readable storage media (including but not limited to magnetic disk storage, optical storage, etc.) having program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the scope of the present invention. Thus, the present invention is also intended to include the modifications and variations of the present invention if they fall within the scope of the claims of the present invention.

Claims (18)

1. switch access point AP method in a kind of WLAN WLAN, it is characterised in that described Method includes：

First AP determines that the site STA being connected with the first AP is in battery saving mode, wherein, it is described First AP is an AP in multiple AP, and the first AP is based on the basic clothes corresponding to the STA Business set identifier BSSID provide service for the STA, the BSSID corresponding to the STA and and institute The BSSID stated corresponding to other any STA of STA in same extended service set ESS is different；

First AP determines that the 2nd AP in the multiple AP in the ESS is target AP, institute State target AP and switch latter linked AP for the STA；

First AP sends wake-up association to the STA, and the wake-up association is used to indicate that the STA exists 2nd AP is in wake states when sending beacon frame based on the BSSID corresponding to the STA；

First AP sends switching command to the 2nd AP, and the switching command is described for indicating 2nd AP provides service based on the BSSID corresponding to the STA for the STA；

First AP is sent after the switching command, stops providing service for the STA.

2. the method as described in claim 1, it is characterised in that the wake-up association includes the first beacon frame, First beacon frame includes the field for being used to update the STA recovery times, described to be used to update described The field of STA recovery times is used to indicate that the STA adjusts recovery time to the 2nd AP based on institute State the time that the BSSID corresponding to STA sends beacon frame.

3. method as claimed in claim 2, it is characterised in that in the first AP to the STA Send before wake-up association, methods described also includes：

First AP determines to receive the time for the second beacon frame that the 2nd AP is sent；

First AP is according to itself beacon frame information time and receives the institute of second beacon frame The time of stating determines the beacon frame information time of the first AP and the beacon frame information time of the 2nd AP Time interval before；

First AP is used for the word for updating the STA recovery times according to being determined the time interval Section.

4. the method as described in claim 1, it is characterised in that the wake-up association includes the 3rd beacon frame, 3rd beacon frame includes the field for indicating that the STA keeps wake states.

5. method as claimed in claim 4, it is characterised in that the wake-up association also includes：Described At least one data frame sent after 3rd beacon frame, at least one described data frame is used to make the STA Keep wake states.

6. method as claimed in claim 5, it is characterised in that at least one described data frame includes sky Data frame.

7. in a kind of WLAN switch AP equipment, the equipment as the AP in the WLAN, Characterized in that, the equipment includes：

First determining module, the STA for determining to be connected with the equipment is in battery saving mode, wherein, The equipment provides service, the STA institutes based on the BSSID corresponding to the STA for the STA Corresponding BSSID with and other any STA in same ESS of the STA corresponding to BSSID It is different；

Second determining module, for determining that the 2nd AP in the ESS is target AP, the target AP Switch latter linked AP for the STA；

First sending module, for sending wake-up association to the STA, the wake-up association is described for indicating STA is when the 2nd AP sends beacon frame based on the BSSID corresponding to the STA in revival shape State；

Second sending module, for sending switching command to the 2nd AP, the switching command is used to refer to Show that the 2nd AP provides service based on the BSSID corresponding to the STA for the STA；

Stop service module, for after second sending module sends the switching command, stopping as institute State STA and service is provided.

8. equipment as claimed in claim 7, it is characterised in that the wake-up association includes the first beacon frame, First beacon frame includes the field for being used to update the STA recovery times, described to be used to update described The field of STA recovery times is used to indicate that the STA adjusts recovery time to the 2nd AP based on institute State the time that the BSSID corresponding to STA sends beacon frame.

9. equipment as claimed in claim 8, it is characterised in that the equipment also includes：

3rd determining module, for before first sending module sends the wake-up association, it is determined that receiving To the time of the 2nd AP the second beacon frames sent；And beacon frame information time according to itself and The time for receiving second beacon frame determines beacon frame information time of the equipment and described the Time interval before the two AP beacon frame information time；And be used for according to being determined the time interval Update the field of the STA recovery times.

10. equipment as claimed in claim 7, it is characterised in that the wake-up association includes the 3rd beacon frame, 3rd beacon frame includes the field for indicating that the STA keeps wake states.

11. equipment as claimed in claim 10, it is characterised in that the wake-up association also includes：Institute At least one data frame sent after the 3rd beacon frame is stated, at least one described data frame is described for making STA keeps wake states.

12. equipment as claimed in claim 11, it is characterised in that at least one described data frame includes Empty data frame.

13. in a kind of WLAN switch AP equipment, the equipment as the AP in the WLAN, Characterized in that, the equipment includes：

Processor, is used for：It is determined that the STA being connected with the equipment is in battery saving mode, wherein, it is described Equipment provides service based on the BSSID corresponding to the STA for the STA, corresponding to the STA BSSID from and other any STA in same ESS of the STA corresponding to BSSID it is different； It is determined that the 2nd AP in the ESS is target AP, the target AP is to connect after the STA switches The AP connect；Wake-up association is generated, the wake-up association is used to indicate that the STA is based on institute in the 2nd AP State when the BSSID corresponding to STA sends beacon frame and be in wake states；Switching command is generated, it is described to cut Changing instruction is used to indicate that the 2nd AP is provided based on the BSSID corresponding to the STA for the STA Service；

Transceiver, couples with the processor, is used for：The wake-up association is sent to the STA；And The switching command is sent to the 2nd AP.

14. equipment as claimed in claim 13, it is characterised in that the wake-up association includes the first beacon Frame, first beacon frame includes the field for being used to update the STA recovery times, described to be used to update The field of the STA recovery times is used to indicate that the STA adjusts recovery time to the 2nd AP The time of beacon frame is sent based on the BSSID corresponding to the STA.

15. equipment as claimed in claim 14, it is characterised in that the transceiver is additionally operable to：Receive The second beacon frame that 2nd AP is sent；

The processor is additionally operable to：Determine that the transceiver receives the time of second beacon frame, and root Received according to the beacon frame information time and the transceiver of the equipment described in second beacon frame Time was determined before the beacon frame information time of the equipment and the beacon frame information time of the 2nd AP Time interval；And the field for updating the STA recovery times is determined according to the time interval.

16. equipment as claimed in claim 13, it is characterised in that the wake-up association includes the 3rd beacon Frame, the 3rd beacon frame includes the field for indicating that the STA keeps wake states.

17. equipment as claimed in claim 16, it is characterised in that the wake-up association also includes：Institute At least one data frame sent after the 3rd beacon frame is stated, at least one described data frame is described for making STA keeps wake states.

18. equipment as claimed in claim 17, it is characterised in that at least one described data frame includes Empty data frame.