WO2016029850A1

WO2016029850A1 - Station control

Info

Publication number: WO2016029850A1
Application number: PCT/CN2015/088110
Authority: WO
Inventors: Guoxiang XU; Haitao Zhang; Tao Zheng
Original assignee: Hangzhou H3C Technologies Co., Ltd.
Priority date: 2014-08-26
Filing date: 2015-08-26
Publication date: 2016-03-03
Also published as: CN105376756A

Abstract

According to one example of the present application, an access point (AP) acquires state information related to a wireless station and determines an association state between said wireless station and said AP according to said state information. The association state is selected from the list comprising : roaming away, association unchanged, non-association unchanged and roaming arrival. The AP implements association processing corresponding to the determined association state so to cause said wireless station to implement wireless association according to said association processing.

Description

Station Control

Background

Wireless Local Area Networks (WLANs) are being applied more and more broadly, e.g., in premises such as marketplaces and homes, because of their flexibility and convenient installation. A WLAN system may include wireless access points (APs) and wireless stations (STAs) that are associated with APs and access the network through APs. Each AP has a certain coverage area. When a STA is moving from one AP's coverage area to another to the coverage area of another AP, the STA experiences handover between the APs and is associated with the new AP. This may be referred to as roaming of a STA.

Brief Description of the Drawings

Fig. 1 is an application scenario diagram of the station control method provided in the present application；

Fig. 2 is a flowchart of a station control method in one example of the present application；

Fig. 3 is a state transition schematic diagram of a wireless station in the station control method in one example of the present application；

Fig. 4 is a roaming diagram in a station control method in one example of the present application；

Fig. 5 is a structure diagram of a wireless access point in one example of the present application； and

Fig. 6 is a hardware architecture diagram of an AP in one example of the present application.

Detailed Description of Embodiments

Referring to Fig. 1, which shows a WLAN including APs and wireless stations STAs, for example, AP1 and AP2. It is assumed that a STA is associated with AP1 and accesses network service through AP1.

Each AP has a certain coverage area such as that shown in Fig. 1 in which an elliptic loop XQ is used to denote the coverage area of AP1. Similarly, AP2 has a certain coverage area which is not shown in Fig. 1. The STA is initially within the coverage of AP1 and associated with AP1. However, in some cases the STA may not be stationary, but may be moving, for example, from the initial location in the coverage area of AP1 to the coverage area of AP2. In this case for AP1, the association state between STA and AP1 may change, for example, from "association unchanged" to "roaming away" . Then the station control method provided in the present application is for AP to determine what state the STA is currently in and implement processing according to the state, so as to facilitate STA to implement AP association corresponding to its state. For example, AP1 in Fig. 1 may cause the STA to disconnect the association with AP1 and associate with AP2. The timing depends upon the configuration of the AP and the situation and in some cases the AP1 may cause the STA to disconnect and associate with the AP2 quickly so as facilitate efficient roaming. Refer to the following detail description for the scheme of how to control.

Fig. 2 is a flowchart of a station control method in one example of the present application, which may be carried out by an AP and as shown in Fig. 2, may include the following blocks.

At block 101, state information related to the wireless station is acquired.

State information refers to the information according to which what an association state (including for example a roaming away state, a roaming arrival state etc. ) a STA and an AP are in. The association state may be determined or decided by the AP, and may for example be based on some measurement parameters such as a STA's signal strength measured by AP or the AP's load, etc. If the signal strength is relatively weak, the AP may determine that the STA is moving away gradually, and may determine that STA is in the roaming away state when the signal strength is below a certain threshold. Alternatively, if the AP's load is relatively large, above a certain load threshold, the AP can decide to have the STA to leave, namely, to no longer accept STA's association.

At this block, the state information related to STA refers to the information that may be obtained by measuring STA related signals, such as the above-mentioned STA's signal strength or other aspects, such as a roaming request message sent by the controller and received by the AP (in which case the message may be considered as the information and the AP may determine that STA is in the roaming arrival state according to the message) . The above-mentioned controller is a network role for integrating AP information in the entire network to implement relevant management； such controller may operate on a certain AP or on separate equipment. For example, the controller may be an access controller (AC) . That is, the information is related to the determination of STA's state, whether they are obtained by direct interaction with the STA or not.

Furthermore, there may also be two scenarios for the AP to acquire the above-mentioned state information: the AP passively listens to the messages sent from STA, including management frames and data frames etc., and obtains the signal strength according to the messages； or the AP actively sends messages to the STA and acquires the above-mentioned state information through response messages returned by the STA.

At block 102, the association state between the wireless station and the AP is determined according to the state information.

After the AP acquires the above-mentioned state information, for example, STA's signal strength, load of AP itself, etc., the association state between STA and AP may be determined according to these information, for example, determining that STA is in a roaming away, a roaming arrival state. Furthermore, the association state between STA and AP determined on AP may include at least one of the following: roaming away, association unchanged, non-association unchanged and roaming arrival. Of course, at a certain moment, the STA is in one of the above-mentioned association states.

Here, the process for the AP to determine the association state between STA and itself according to the state information will be described in detail in the following examples.

At block 103, association processing corresponding to the association state is implemented according to the association state between STA and AP.

In one example, the AP may implement corresponding processing according to the association state determined by itself between wireless station and AP, so as to facilitate STA to implement more reasonable AP association. For example, when AP determines STA is roaming away, AP may actively send a de-association message to the STA to disconnect with the STA； or reduce the transmission power for beacon frames to force the STA to select other APs.

With the station control method provided by the present application, an AP can influence wireless association of a wireless station by determining the association state of a wireless station and implementing association processing corresponding to the state, so as for the wireless station to associate according to the association processing, which makes the association between wireless station and AP more reasonable and in turn can improve the network performance.

While at present, the manner in which STA is roaming, for example, includes, STA measures the AP's signal strength received by it: when the currently associated AP's signal strength gradually decreases to a threshold value, while a new AP's signal strength is relatively strong, the STA would disconnect with the currently associated AP and switch to the new AP. But the problem with this case is that, the STA is stuck to the currently associated AP and will switch to the new AP until the currently associated AP's signal strength is very low, that is, the STA itself cannot switch to a more suitable AP in time, which impacts the network performance. Furthermore, the new AP selected by STA may already have large load, then after association the STA cannot obtain good bandwidth etc. In summary, unreasonable conditions may occur when STA is associating AP, which influences the overall network performance, such as lowering the STA's network speed.

In one example, in order for a more accurate determination of association state between STA and AP by AP, when AP acquires the state information related to STA, it can further acquire parameters other than signal strength. For example, STA can acquire parameters such as the signal strength and the time of flight in air of wireless messages to determine association state between STA and AP comprehensively. Further, AP will implement different association processing according to different association states between STA and AP. Each stage will be described in detail below respectively in the order of acquiring information by AP → state determining → association processing.

Acquiring information:

AP can determine the association state between STA and AP according to STA's state information. When the association state between STA and AP is determined, AP can implement association processing corresponding to the state according to the association state. So acquiring STA's state information is the basis for AP to implement association processing. In one example, AP can acquire a plurality of state information for determining association state between STA and AP and the state information may be referred to as information indicator. For example, the indicator may include the signal strength or received signal strength indicator (RSSI) , time of flight in air (TOF) , certain transmission rate of messages and corresponding success ratio, AP's load, etc. The TOF, success ratio etc. may be referred to as "message transmission parameters" .

The above indicators are described briefly below.

Signal strength or RSSI: a measurement indicator used to represent the magnitude of energy sensed by AP's radio frequency unit while receiving signals, with larger values representing larger energy of the received signals, and that STA is closer to AP.

TOF: time of flight in air of a wireless message, such as the time of flight in air for a message from AP to STA or from STA to AP. In one example, the TOF value is a half of total time value for a round trip of a message. For example, the AP sends a message to STA at time t1, and receives a response message returned by STA at time t2, and then the half of the time difference between t1 and t2 is referred to as TOF.

And in this example, while determining the association state between STA and AP according to TOF, at least two TOF values may be acquired and the association state between STA and AP is determined according to the variation tendency of these at least two TOF values as measurement time approaches. For example, assuming the TOF measured at the time point of one minute before is 1.5 millisecond, while the TOF measured at the current time point is 1.6 millisecond, that is, as the measurement time approaches the current time, TOF increases gradually, then it may be determined that STA is gradually moving away from AP, since TOF is generally positively correlated with distance.

Certain transmission rate and corresponding success ratio of a wireless message: when AP and STA is apart from each other by a certain distance, a wireless message is transmitted at different transmission rates, then the transmission success ratio of the wireless message is also different (receiving returned response message may be considered as success, otherwise failure) . For example, when STA and AP are a certain distance apart, when transmitting a wireless message at a certain transmission rate at this distance, assuming the success ratio should be s1, then s1 may be referred to as the threshold value, and if the practical success ratio is below the threshold value, it means STA is further. Based on this, AP may set a threshold value for success ratio and determine the association state between STA and AP is roaming away if the practical success ratio is below the threshold value.

AP's load: since when there are too many STAs associated with an AP, the STA may not obtain enough bandwidth, which impacts the STA's network performance, so AP may determine whether STA is associated according to the load condition of its own. For example, it is assumed that AP may set that at most 7 STAs may be associated beforehand, and then the number 7 may be a threshold value. If AP's load is equal to or greater than this threshold value, AP can determine that the association state between STA and AP is roaming away and further implement processing for facilitating STA to move away.

The Table 1 below enumerates some information indicators related to STA collected on AP:

Table 1 Information indicator related to STA

In the above-mentioned Table 1, some of information indicators obtained by AP are illustrated, and AP may also acquire more information for determining association state between STA and AP. Furthermore, two TOF indicators are illustrated in Table 1. While in practical implementations, AP may obtain three, four or more TOFs to determine the moving tendency of STA more accurately. Similarly, also one transmission rate and corresponding success ratio are illustrated in Table 1. In practice, AP may save several, e.g., two transmission rates, and transmits wireless messages at these rates to acquire corresponding success ratio. Optionally, for the information indicators in Table 1, AP can select to acquire one or more of them. For example, acquiring two indicators, namely signal strength and TOF to determine association state between STA and AP results in a more accurate determination than acquiring one indicator, the signal strength.

Furthermore, acquiring state information at this block not only includes indicators such as the above-mentioned signal strength and TOF, but also includes the messages sent by the controller received by AP such as a roaming request message, and the block of determining association state between STA and AP according to the message will be described in detail in the following "state determination" .

Even further, the above-mentioned information indicator may be acquired by AP passively listening to a message sent from STA, for example, AP listening to a management frame, a control frame, a data frame etc. sent from STA, and AP can obtain for example signal strength or RSSI while receiving these frames.

Alternatively, when AP does not send traffics to STA in a certain period, AP may actively send a detection message to STA to acquire information indicator of STA. For example, for non-associated STA, it may send a Null Data frame to obtain Ack response which is the response message returned for the detection message Null Data frame, and for an associated STA, it may send a Ping package to obtain Ack message and Ping response message and can measure indicators such as measurement signal strength, TOF or success ratio according to these messages. In the present application, state information is obtained by AP actively sending messages to STA, which facilitates AP to analyze these information to find out what association state STA and AP are in, and if it is the roaming away state, it can facilitate association switching of STA in time.

In the present application, AP may periodically collect the above-mentioned information indicators, for example for every other time t (t≥1s) . In case that a controller is available, AP may report these information to the controller periodically, and the controller may form the following Table 2 by combining the STA's information reported by various APs according to the STA's MAC as index.

Table 2 Information indicator related to STA

In the table, the controller may learn about the measurement of information indicators of a certain STA in each APs, for example, STA1 measures a high signal strength at AP1 while a low signal strength at AP3. The controller may select an AP more suitable for associating with STA according to the above-mentioned information, for example, selecting AP1 with high signal strength as the AP suitable for associating with STA1. The specific distribution of the selected AP's information by the controller will be described in the following state determination and association processing stages.

State determining:

After collecting the above-mentioned information indicator, AP will determine association state between STA and AP according to the indicator. In one example, AP will record the association state between STA and AP for each STA in its coverage. The association states set in this example includes four types. Referring to Fig. 3, the association states include association unchanged, roaming away, non-association unchanged and roaming arrival, wherein the association unchanged and roaming away are two states when STA is associated to AP, while non-association unchanged and roaming arrival are two states when STA is not associated with AP.

It is to be noted that the above-mentioned example is explained with an example in which four association states of STA are set on AP. They may also be not four types. For example, the association states between STA and AP set on AP include at least three types, e.g., including "association unchanged, roaming away and roaming arrival" , and a determination is made regarding which state of the three states STA is in at a certain moment. As another example, it is also possible to set on AP that association states between STA and AP include at least two types, for example, including "association unchanged" and "roaming away" . As another example, it is also possible to set on AP that association states between STA and AP include at least one type, for example, including "roaming arrival" , and the association processing for facilitating STA roaming is implemented when it is determined that STA is in the roaming arrival state. The determination of four states will be described below as an example, and other cases will not be described in detail any longer.

As shown in Fig. 3, switching between association states is triggered by trigger events. For example, when trigger event 1 occurs, AP may determine according to this that the association state between STA and AP is switching from "association unchanged" to "roaming away" , that is, trigger event 1 is the condition for AP to determine roaming away of STA. Other association states between STA and AP are determined in the same manner, wherein trigger event 5 is disconnection between STA and AP, and trigger event 6 is the establishment of connection between STA and AP. The determination of trigger event 1, trigger event 2, trigger event 3 and trigger event 4 will be described below.

Furthermore, networks may be classified into cases of "without controller" and "with controller" . For these two cases, determination of association states between STA and AP differs slightly, which will be described below.

Without Controller:

the occurrence of trigger event 1 may be based on at least one of the following conditions:

a) Signal strength being less than threshold value S1；

b) Signal strength being less than threshold value S1, and TOF1>TOF2>TOF3 (the collection time corresponding to TOF1 is approaching the current time) ；

c) Signal strength being less than threshold value S1 and success ratio k<threshold value F1；

d) Signal strength being less than threshold value S1, and load on AP being higher than threshold value L1.

It is to be noted that the four cases a) ～ d) listed for the above-mentioned trigger event 1 may also be optional, and in specific implementations, other conditions may be used as trigger events. For example, determination may be made according to TOF alone. If TOF1>TOF2>TOF3, it is determined that STA is moving away, and as the trigger event for roaming away TOF is no longer used together with signal strength for comprehensive determination. Similarly, it is also possible to make determination according to success ratio alone, and if success ratio k<threshold value F1, roaming away is determined. Furthermore, the signal strength in the above-mentioned trigger event 1 may also be substituted for RSSI for determination.

The occurrence of trigger event 2 may be based on at least one of the following conditions, that is, the occurrence of at least one indicates that STA is returning to the coverage of associated AP again. Generally, trigger event 2 and trigger event 1 are contrary determinations.

The occurrence of trigger event 2 may be based on at least one of the following conditions:

a) Signal strength being greater than threshold value S2；

b) Signal strength being greater than threshold value S2, and TOF1<TOF2<TOF3 (the collection time corresponding to TOF1 is approaching to the current time) ；

c) Signal strength being greater than threshold value S2 and success ratio k>threshold value F2；

the condition for trigger event 3 is similar to that for trigger event 2. However, different threshold value may be used. Trigger event 4 is similar to trigger event 1.

With Controller:

in this case, the manner for AP to determine STA is substantially identical to the case without controller. But the determination of trigger event 3 and trigger event 4 are slightly different. AP can determine association state between STA and AP according to the received roaming state notification message sent by the controller which may be a roaming request message or a roaming cancelling message, for example:

the occurrence of trigger event 3 may be based on the following conditions:

a) AP receiving a roam-out request message sent by the controller.

The occurrence of trigger event 4 may be based on the following conditions:

a) AP receiving a roam-out cancel message sent by the controller； or

b) Conditions being similar to trigger event 1 but with different threshold values.

The above-mentioned messages are sent in the following ways.

For example, when the association state between STA and AP is roaming away, the AP associated with the STA will transmit a roam-out message to the controller which carries the STA's MAC identification. When the controller receives the message, it selects several (generally less than or equal to 3) other APs suitable for association with STA according to the STA's information already collected, for example, the information in Table 2.

Referring to Fig. 4, in the moving process of STA (notebook) , when the AP1 associated therewith determines it's roaming away, it transmits a roam-out request message to the controller AC. AC selects a number of APs from other APs such as AP2, AP3, AP4 and AP5 etc., as candidate APs for STA roaming switching. It is assumed that AP2 and AP5 are selected. AC forwards the roam-out request message received by AP1 to AP2 and AP5 to inform these two APs that they will be the APs to be switched to. At this point, after AP2 and AP5 received the roam-out request message indicating occurrence of trigger event 3, they record the association state between STA and AP as roaming arrival.

At the same time, AC would return a roam-out response message to AP1 in which a list of APs selected by AC is carried, for example, inform AP1 the to-be-selected AP2 and AP5, such that AP1 informs the list to STA that can select an AP to associate with according to this list.

In one example of the present application, the controller AC may select APs to be switched to in various ways, for example:

a) Ranking the signal strengths of all APs in regard to the STA in descending order and selecting the first 5 APs as APs to be switched to；

b) According to TOF, TOF1 (APk) <TOF1 (AP1) , wherein, APk is the selected AP.

Furthermore, when the STA's state changes from roaming away to association unchanged, or from roaming away to non-association unchanged, AP would send a roam-out cancel message to the controller. The controller forwards the message to those APs that have received (or been sent to) roam-out request message after receiving the message and these APs can determine the occurrence of trigger event 4 according to the roam-out cancel message, thereby determining the STA's state is changing from roaming arrival to non-association unchanged.

Association processing:

In one example of the present application, when determining the association state between STA and AP, AP would implement corresponding association processing according to the state, such that STA can be adjusted to the proper AP in time, wherein in the association unchanged state, AP may not take any action.

In the roaming away state, AP can implement one or more of the following actions.

a) AP sending a de-association message or a de-authentication message to STA, which will facilitate STA to disconnect with AP so as to associate with other proper APs as soon as possible.

b) AP reducing transmission power of management frame that includes at least one of the following: a beacon frame, or a probe response frame for probe request of STA. By reducing the transmission power of management frame, AP will not be selected at STA side and STA will be adjusted to other APs for association.

c) If STA supports 802.11k or 802.11v standard, AP can include the selected AP in the roaming response message returned by AC in the candidate neighbor list of the neighbor report message sent to STA, or the candidate neighbor list of the basic service set transition management request message, such that STA can transit to the APs in the candidate neighbor list as soon as possible according to the list.

In the non-association unchanged state, AP can implement one or more of the following actions.

a) AP not responding to the probe request message of STA, that is, neglecting the probe request frame sent from STA. By not responding to the message, STA chooses not to associate with the AP but moves to other APs for association.

b) AP rejects the association request, or rejects it for a certain times, such as one or two times while receiving the association request of STA.

In the roaming arrival state, AP can implement the following actions: increasing transmission power of management frame that includes at least one of a beacon frame or a probe response frame for STA's probe request.

Fig. 5 is a structure diagram of a wireless access point in one example of the present application, the equipment of which can implement the station control method provided in the present application. As shown in Fig. 5, the equipment may include an information acquisition unit 51, a state determination unit 52 and a station control unit 53.

The information acquisition unit 51 is configured to acquire state information related to a wireless station, which includes, for example, roaming away, association unchanged, non-association unchanged and roaming arrival.

The state determination unit 52 is configured to determine the association state between said wireless station and an AP according to said state information.

The station control unit 53 is configured to implement the association processing corresponding to said association state according to said association state, so as for said wireless station to implement wireless association according to said association processing.

In some examples, the information acquisition unit 51 is configured to acquire at least two periods of transmission time of transmitting a wireless message between the local device and said wireless station.

Said state determination unit 52 is configured to determine the association state between said wireless station and AP according to the variation tendency of said at least two periods of transmission time as the measurement time approaches the current time.

The information acquisition unit 51 is configured to acquire the success ratio of transmitting said wireless message when transmitting a wireless message at a preset transmission rate.

Said state determination unit 52 is configured to determine the association state between said wireless station and AP according to said success ratio and the success ratio threshold value corresponding to said preset transmission rate.

The information acquisition unit 51 may be configured to receive the roaming state notification message corresponding to said wireless station sent by the controller.

Said state determination unit 52 is configured to determine the association state between said wireless station and an AP according to said roaming state notification message.

The station control unit 53 may be further configured to implement at least one of the following processings.

When said state determination unit determines that the association state is roaming away, it reduces transmission power of the management frame that includes at least one of a beacon frame and a probe response frame.

In another example, when said state determination unit determines that the association state is roaming arrival, it increases transmission power of the management frame that includes at least one of a beacon frame and a probe response frame.

In another example, when said state determination unit determines that the association state is non-association unchanged, it neglects the probe request frame sent by said wireless station or rejects the association request of said station.

The information acquisition unit 51 may be further configured to send a probe message to said wireless station and acquire said state information according to the response message returned by said wireless station for said probe message.

Fig. 6 is a hardware architecture diagram of an AP in one example of the present application. In this example, AP generally includes a processor 61 and a non-transitory machine readable storage medium 62. The processor 61 and the non-transitory machine readable storage medium 62 may be communicatively connected with each other via an internal bus 64. In addition, AP in the present application may further include other hardware such as a communication interface 63 to facilitate receiving or transmitting data.

As shown in Fig. 6, the station control logic device 65 is stored in the non-transitory machine readable storage medium 62 in the form of machine readable instructions, and the processor 61 performs the following operations by executing instructions corresponding to the station control logic device 65 stored in the non-transitory machine readable storage medium 62.

Acquiring state information related to the wireless station；

determining an association state between said wireless station and said AP according to said state information, said association state including at least one of the following: roaming away, association unchanged, non-association unchanged and roaming arrival； and

implementing the association processing corresponding to said association state according to said association state, so as for said wireless station to implement wireless association according to said association processing.

In one example, wherein the state information acquired by said AP comprises parameters selected from the list comprising:

a message transmission parameter that is at least two periods of transmission time for transmitting a wireless message between said AP and said wireless station；

the state information acquired by said AP includes a message transmission parameter that is the success ratio of transmitting a wireless message when transmitting said wireless message at a preset transmission rate；

the signal strength of said wireless station； and

the received signal strength indicator RSSI of said wireless station.

In one example, the state information acquired by said AP includes a message transmission parameter that is at least two periods of transmission time for transmitting a wireless message between said AP and said wireless station.

For said determining the association state between said wireless station and said AP according to said state information, the non-transitory machine readable storage medium 62 is further to store machine readable instructions that are executable by the processor to:

determine the association state between said wireless station and said AP according to said message transmission parameter； and includes: determining the association state between said wireless station and said AP according to the variation tendency of said at least two periods of transmission time as the measurement time approaches the current time.

In one example, the state information acquired by said AP includes a message transmission parameter that is the success ratio of transmitting a wireless message when transmitting said wireless message at a preset transmission rate.

determine the association state between said wireless station and AP according to said message transmission parameter； and includes determining the association state between said wireless station and AP according to said success ratio and the success ratio threshold value corresponding to said preset transmission rate.

In one example, the state information acquired by said AP further includes the signal strength of said wireless station or the received signal strength indicator RSSI.

For said determining the association state between said wireless station and said AP according to said state information , the non-transitory machine readable storage medium 62 is further to store machine readable instructions that are executable by the processor to

determine the association state between said wireless station and said AP according to said signal strength or the RSSI in combination with said message transmission parameter.

In one example, for said acquiring the state information related to the wireless station and determining the association state between said wireless station and said AP according to said state information , the non-transitory machine readable storage medium 62 is further to store machine readable instructions that are executable by the processor to:

determine the association state between said wireless station and said AP according to the received roaming state notification message corresponding to said wireless station sent by the controller.

In one example, for said acquiring the state information related to the wireless station, the non-transitory machine readable storage medium 62 is further to store machine readable instructions that are executable by the processor to:

receive a roaming state notification message corresponding to said wireless station sent by the controller.

In one example, for said implementing the association processing corresponding to said association state according to the association state, the non-transitory machine readable storage medium 62 is further to store machine readable instructions that are executable by the processor to:

reduce transmission power of management frame that includes at least one of a beacon frame and a probe response frame when said association state is roaming away；

increase transmitting power of management frame that includes at least one of a beacon frame and a probe response frame when said association state is roaming arrival；

neglect the probe request frame sent by said wireless station or rejecting the association request of said station when said association state is non-association unchanged.

Claims

A station control method comprising:

acquiring, by a wireless access point (AP) , state information related to a wireless station；

determining, by said AP, an association state between said wireless station and said AP according to said state information, said association state including a state selected from the list comprising: roaming away, association unchanged, non-association unchanged and roaming arrival； and

implementing, by said AP, an association processing corresponding to the determined association state, so as to cause said wireless station to implement wireless association according to said association processing.
The method according to claim 1, wherein the state information acquired by said AP comprises at least one parameter selected from the list comprising:

a message transmission parameter that is at least two periods of transmission time for transmitting a wireless message between said AP and said wireless station,

a message transmission parameter that is the success ratio of transmitting a wireless message when transmitting said wireless message at a preset transmission rate,

the signal strength of said wireless station； and

the received signal strength indicator RSSI of said wireless station.
The method according to claim 2, wherein said determining, by said AP, the association state between said wireless station and said AP according to said state information comprises:

determining, by said AP, the association state between said wireless station and said AP according to a variation tendency of said at least two periods of transmission time as a measurement time approaches the current time.
The method according to claim 2, wherein said determining, by said AP, the association state between said wireless station and said AP according to said state comprises:

determining, by said AP, the association state between said wireless station and said AP according to said success ratio and a success ratio threshold value corresponding to said preset transmission rate.
The method according to claim 2, wherein said determining, by said AP, the association state between said wireless station and said AP according to said state information comprises:

determining, by said AP, the association state between said wireless station and said AP according to said signal strength or the RSSI in combination with said message transmission parameter.
The method according to claim 1, wherein said acquiring, by said AP, the state information related to the wireless station comprises:

receiving, by said AP, a roaming state notification message corresponding to said wireless station sent by the controller.
The method according to claim 1, wherein said implementing, by said AP, the association processing corresponding to said association state according to said association state comprises:

when said association state is roaming away, reducing, by said AP, transmission power of management frame that includes at least one of a beacon frame and/or a probe response frame；

when said association state is roaming arrival, increasing, by said AP, transmission power of management frame that includes at least one of a beacon frame and/or a probe response frame；

when said association state is non-association unchanged, by said AP, neglecting the probe request frame sent by said wireless station or rejecting the association request of said terminal.
A wireless access point AP, comprising a processor and a non-transitory machine readable storage medium storing instructions which are executable by the processor to:

acquire state information related to the wireless station；

determine an association state between said wireless station and said AP according to said state information, said association state include states selected from the list comprising: roaming away, association unchanged, non-association unchanged and roaming arrival； and

implement the association processing corresponding said association state according to said association state, so as for said wireless station to implement wireless association according to said association processing.
The AP according to claim 8, wherein the state information acquired by said AP comprises a parameter selected from the list comprising:

a message transmission parameter that is at least two periods of transmission time for transmitting a wireless message between said AP and said wireless station；

a message transmission parameter that is the success ratio of transmitting a wireless message when transmitting said wireless message at a preset transmission rate；

the signal strength of said wireless station； and

the received signal strength indicator RSSI of said wireless station.
The AP according to claim 9, wherein the machine readable instructions further includes instructions executable by the processor to:

determine the association state between said wireless station and said AP according to the variation tendency of said at least two periods of transmission time as a measurement time approaches the current time.
The AP according to claim 9, wherein the machine readable instructions further includes instructions executable by the processor to:

determine the association state between said wireless station and AP according to said success ratio and the success ratio threshold value corresponding to said preset transmission rate.
The AP according to claim 9, wherein the machine readable instructions include instructions that are executable by the processor to:

determine the association state between said wireless station and said AP according to said signal strength or the RSSI in combination with said message transmission parameter.
The AP according to claim 8, for said acquiring the state information related to the wireless station, the non-transitory machine readable storage medium is further to store machine readable instructions that are executable by the processor to:

receive a roaming state notification message corresponding to said wireless station sent by the controller.
The AP according to claim 8, wherein the machine readable instructions further include instructions to implement the association processing corresponding to said association state by:

reducing transmission power of management frame that includes at least one of a beacon frame and/or a probe response frame when said association state is roaming away；

increasing transmission power of management frame that includes at least one of a beacon frame and/or a probe response frame when said association state is roaming arrival；

neglecting the probe request frame sent by said wireless station or rejecting the association request of said station when said association state is non-association unchanged.