CN101019443A

CN101019443A - Seamless channel change in a wireless local area network

Info

Publication number: CN101019443A
Application number: CN 200580030612
Authority: CN
Inventors: 安吉罗·卡费洛; 克里斯多福·凯夫; 保罗·马里内尔; 文森特·罗伊
Original assignee: InterDigital Technology Corp
Current assignee: InterDigital Technology Corp
Priority date: 2004-09-10
Filing date: 2005-09-06
Publication date: 2007-08-15
Also published as: CN2877154Y

Abstract

A method for seamless channel change in a wireless local area network having a station STA (204) and an access point AP (202) begins with sending a channel change intention message from the AP to STA (210). A channel change response message (212) is sent from STA to the AP, informing the AP whether the STA will follow the channel change. The AP determines whether to proceed with the channel change, and performs the change if the determination is positive.

Description

The Wireless LAN seamless channel change

Technical field

The invention relates to a kind of Wireless LAN (WLAN), the present invention especially about a kind of in a WLAN method of seamless channel change.

Background technology

In the wlan system that in infrastructure mode, operates, be linked to an access point (AP) of a basic service set (BSS), typically have the coupled knot of one or more platforms (STAs).This AP and relevant STAs thereof when this channel is crowded (also, flow shown on this channel is very high), just need the node of BSS to use more crowded channel by send and receive information bag to communicate with one another on a given channel.Similarly, if this channel is subjected to the influence of system external disturbance,, but wishes and also need the different channel of BSS node use though this is more common on unwarranted frequency band.

BSSs changes the most typical method of channel, it transmits the channel of all frames (management, control and data) to this AP at a specific time changing, this expression STA will stop to receive any frame from its AP suddenly, and all frames that will deliver to AP are considered as non-affirmation, the service responsive for service quality (QoS), this service disruption can't satisfy the user.

In order to satisfy the regulatory demand that in the 5 GHz frequency bands in Europe, operates, made correction (IEEE 802.11h) in WLAN medium access control (MAC) and physical layer (PHY) specification, allow in the wlan system and the radar system of 5GHZ frequency band in the correction and deposit, but it does not provide and makes terminal temperature difference seamless and effectively utilize the method for Radio Resource to implement channel-changing, when AP or its channel of STA decision replacing, the family of 802.11 standards does not provide any hand (hand-shaking) form of changing to guarantee seamless channel change.

Operating on the system of infrastructure mode, 803.11h specification comprises a notification message, it allows this AP to notify this STA future with switching channels, in high-level, there are three selections to make this notice possess acceptance condition, and this channel will switch, and it should be noted that prior art does not provide any mechanism for following situation:

1) STA request AP changes channel.

2) STA confirms to receive the notice from AP, and it will follow this AP replacing to new channel.In 802.11h, notice is to use broadcasting to implement, so AP do not receive any affirmation (ACK) and make it can judge whether this STA will follow to this new channel, or whether this STA correctly receives this notice.This can cause a kind of situation, be an AP do not need to transmit and again transmission frame give and not follow the STA of AP to new channel, the number of frames that cushions in AP may be very a large amount of, and will cause wireless medium very inefficent, this is because the relevant multiple window that falls back of transmission again can present the growth of exponential type.

3) STA confirms that it has followed AP to new channel, and this can produce inefficiency situation similar to the above.

Therefore, the method and apparatus that needs a kind of seamless channel change in a WLAN is just arranged.

Summary of the invention

Therefore the present invention overcomes the restriction of prior art, allows to carry out seamless channel change at a WLAN, and does not need break in service and can significantly not reduce the efficient of wireless medium.

A kind of have the method for seamless channel change among the WLAN of a STA and an AP one.At first send a channel-changing intent message to this STA by this AP.Then send a channel-changing response message to this AP, notify this STA of this AP whether will follow channel-changing by this STA.This AP judges whether continue channel-changing, and if be judged to be and be, just carry out this channel-changing.

Another kind of have the method for seamless channel change among the WLAN of a STA and an AP one.At first send a channel-changing request to this AP by this STA.Judge whether can carry out channel-changing, and this channel-changing is to carry out according to this judgement.

Two methods all comprise a non-essential additional step, and it is the successful execution according to this channel-changing, send a channel-changing by this STA and carry out message to this AP.

A kind ofly comprise in the Wireless LAN of an AP and a STA, carry out the system of a seamless channel change one.This AP is configured to send a channel-changing intent message to this STA.This STA is configured to send a channel-changing response message to this AP, comprises an indication, indicates this STA whether will follow the new channel of this AP to one.After receiving this channel-changing response message, this AP more is configured to judge whether will continue channel-changing, if just and to be judged to be to carry out this channel-changing.Although this AP will consider the response message from this STA, the decision that whether continues this channel-changing does not need according to this response message.

Another kind comprises in the Wireless LAN of an AP and a STA one, carries out the system of a seamless channel change.This STA is configured to send a channel-changing request message to this AP.Only support in the example of a STA at AP, this AP is configured to judge whether this channel-changing can be performed, and judges this channel-changing of execution according to this.Support in the example of the STA that surpasses at AP, this AP is configured to begin aforesaid channel-changing program via this channel-changing intent message.

A kind ofly comprise in the Wireless LAN of an AP and a STA, carry out the system of a seamless channel change one.This AP comprises one first channel-changing notifying device; One first channel-changing decision maker, it is to be connected to this first channel-changing notifying device; One measurement request device, it is to be connected to this first channel-changing decision maker; One first transmitter/receiver, it is to be connected to this first channel-changing notifying device, this first channel-changing device and this measurement request device; And one first antenna, it is to be connected to this first transmitter/receiver.This STA comprises a second channel and changes notifying device; One second channel changes decision maker, and it is to be connected to this second channel to change notifying device; One platform capability device, it is to be connected to this second channel to change decision maker; One second channel modifier, it is to be connected to this second channel to change decision maker; One second transmitter/receiver, it is to be connected to this second channel change notifying device and this second channel modifier; One measurement report device, it is to be connected to this second transmitter/receiver; And one second antenna, it is to be connected to this second transmitter/receiver.

Description of drawings

By the description of a hereinafter preferred embodiment, the example that is given, with reference to corresponding accompanying drawing, the present invention can obtain to understand in more detail, wherein:

Figure 1 shows that initial seamless channel change method flow diagram by AP;

Figure 2 shows that the signal flow graph of method shown in Figure 1;

Figure 3 shows that initial seamless channel change method flow diagram by a STA; And

Figure 4 shows that a system block diagrams, it is to be configured to implement a seamless channel change.

Embodiment

After this, proprietary term " platform (STA) ", it comprises but is not limited to, a wireless transmission/receive unit, a subscriber equipment, a fixing or moving user unit, a calling set or any type of device that can operate under a wireless environment.When after this this paper mention proprietary term " access point (AP) ", it comprises but is not limited to, a platform, a Node B, a platform controller or any type of interface arrangement under wireless environment.

The present invention addresses the above problem, and it is by setting the hand-exchanging program between an AP and a STA, the wherein coupled STAs communication of this AP, and it notify with switching channels, and wherein this STA confirms that it will or will can not follow at the new AP of channel.This program guarantees that discernable all AP of all STAs change the notice of channels, and which STA AP also can know and can follow to new channel, and which STAs has followed the new channel that the AP decision changes.The present invention is also by allowing STA request channel-changing to solve problem to trigger hand-exchanging program.

Fig. 1 in order to simplify accompanying drawing and discussion of the present invention, hereinafter only talks about a single S TA with the initial hand-exchanging program 100 of description of drawings AP of the present invention, and principle of the present invention is also applicable to the system of a plurality of STAs.

One AP sends channel-changing intent message to a STA, changes channel to channel X to indicate its intention, and wherein X represents channel identifier (step 102).This message also comprises the message about the channel-changing time, this message can use broadcast frame or clean culture to send frame to send, use the benefit of broadcast frame to be, when a plurality of STAs link to each other with this AP, the quantity that its restriction message sends on wireless medium, use the benefit of single broadcasting frame (one of the STA that each links to each other) to be, the robustness that it helps signal to send, because this AP can wait for the MAC ACK from STA, indicate this STA whether correctly to receive message, in the example of not receiving from the ACK of specific STA, AP can resend this channel-changing intent message.

According to the channel-changing intent message that receives, STA can judge whether will change its channel to this new channel (step 104) based on the wireless frequency environment of its ability, its present position and validity and the load of other APs in system.This judgement can involve a multiple criteria determination procedure, for instance, first criterion that this STA can consider is, whether it has ability (considering the restriction of hardware and configuration) changes to channel X, as being declared by the channel-changing intent message that AP sent.STA may consider second and the 3rd criterion be the level of interference of STA and load on channel X.According to this kind criterion, this STA just determines whether need this channel-changing, and the multiple criteria analysis that this conclusion can use any row to be is reached, and it is will to calculate the mark that obtained and a predetermined level comparison based on weights and obtain.

In case make decision, STA just sends a channel-changing response message, and it comprises a notice, notifies this message to be received (also can be used for using in the example of broadcast transmission channel-changing intent message), and an indication, indicate this STA whether will follow this AP to new channel (step 106).

Indication in the channel-changing response message has comprised different predefine and has responded, its including but not limited to:

1) this STA will follow this AP to new channel.

2) this STA will can not follow to new channel, and will be ready to continue to be served on the channel that communicates by AP.If the scan ability or the STA that indicate new channel will reduce its usefulness or STA shortage change channel of STA judge that changing channel can't make the QoS demand of its application facet that satisfies the user, can improve just the probability of this situation then takes place.

3) STA will not follow AP to new channel, but can not ask AP to treat at identical channel.If STA has identified another candidate AP, and judge that it can provide than the better usefulness of existing AP on new channel, can improve just the probability of this situation then takes place.

STA can carry out the technical scope that channel-changing is judged, be included on the new channel use measure or report quality yardstick (for example: the signal noise disturb than (SNR), signal and noise than (SINR), packets of information error rate (PER) or the like), and with these yardsticks and the quality scale ratio on existing channel, measured, or with predetermined level relatively.STA also uses and measures on new channel or the load yardstick (for example: channel occupancy, medium access delay or the like) of report, with load scale ratio measured on existing channel, or with predetermined level relatively.Also can use the weights benchmark combination of above-mentioned yardstick on new channel, compare with the weights benchmark combination of same scale on existing channel, or compare with predetermined level.

If AP uses its channel-changing intent message of broadcast transmission, also receive the purpose use of this channel-changing intent message by this channel-changing response message that STA sent as affirmation.With the single broadcasting message transmitting channel message that changes one's intention several benefits is arranged, because it allows AP to distinguish out the STA that does not receive the channel-changing intent message, and receive the channel-changing intent message but do not send the STA of this channel-changing response message, this APc can wait for the response (plus or minus) of all STAs or till expiring, whether with frequency band change continue, and AP can not limited by the suggestion of STA yet if then just making a determination.

According to the channel-changing response notification that receives from STA, whether this AP then decision will change this channel (step 108), this step allows this AP to consider the intention that it changes channel again, for instance, only serving a single STA and this STA at AP indicates it not follow this AP to example of new channel, this AP may determine not carry out channel-changing, can help it to make better decision if AP believes measurement report, and this also is to measure to the STAs request to the AP chance.

Generally speaking, the judgement whether this AP continues channel-changing is based on, and with the user's of the channel-changing message response of each pattern relative populations, carries out the influence of this channel-changing cause to service quality with prediction.Relatively each form relative populations of responding and usefulness of predicting according to this channel of switching changes the program that target is made decision, and also is one of several possibility executive modes.

If this AP decision does not change channel, just program 100 stops (step 110).If the AP decision continues channel-changing (step 108), then it sends a channel-changing notification message to the STA (step 112) that links to each other.This message also comprises the information about the channel-changing time, and this message can use broadcast frame or single broadcasting frame sends, and the advantage of each form is with mentioned above identical.

If the AP decision continues channel-changing, it can use the information that is contained in the channel-changing response message that is received from STA, and remove all and belong to the buffer information bag that the STA of the extremely new channel of AP is not followed in response, if STA does not follow AP to new channel, then this can prevent that a large amount of banded amount of AP waste is on unsuccessful transport packet.This AP changes to new channel (step 114), and if STA follow this AP, this STA also changes to new channel (step 116).

The inessential step of a hand-exchanging program is, after STA changes channel, send a channel-changing and carry out message to this AP (step 118), this information also can be used for preventing this AP waste frequency band in unsuccessful ground transport packet to STA, this STA indicates (in its channel-changing response message) will follow this AP to new channel, but can't reach.Then this program becomes termination (step 110).

Figure 2 shows that system's 200 signal graphs of carrying out program shown in Figure 1, this system 200 comprises an AP 202 and a STA 204.This AP 202 sends a channel-changing intent message 210, and it can be broadcasted or single broadcasting sends.This STA 204 (or each STA 204, its be if this AP 202 to have a plurality of STAs coupled) by send a channel-changing response message 212 to this AP 202 to respond this intent message 210, each STA 204 sends its response message with single broadcasting message.

Take place if this frequency band changes, just this AP 202 sends a channel-changing notification message 214 to this STA 204, as intent message 210, this notification message 214 can broadcast message or the transmission of single broadcasting message.This STA 204 can send a channel-changing according to the channel-changing of success and carry out message 216 to this AP 202, and it is to be a non-essential message.

Figure 3 shows that the method according to this invention 300 flow charts, wherein a STA asks this AP to change its channel.In a preferred implementation, the present invention makes this STA ask it to change employed channel to this AP, and when the critical QoS to the user of interference that this STA suffered or channel activity power, the needs of this kind request just can rise.

This STA sends one with a single broadcasting frame and changes the channel request message to its AP (step 302), this message can comprise following in some or all information: carry out the time restriction of this channel-changing, preferable channel table and the interference on existing and candidate channel or the noise level measurement of desire migration.

According to the message that is received, this AP then can take one or two action.If this AP has a plurality of coupled STAs, then it makes this AP begin to carry out hand-exchanging program 100, is begun by step 102.If it is coupled that this AP only has a single STA, then very can determine to continue this channel-changing program, and begin to carry out this program 100 by step 108.

In the flow process of the described any point of Fig. 1, this AP can take to measure on the channel of existing and recommendation, and/or requires the STA of request channel-changing to measure.

Channel 4 is for being configured to carry out system's 400 schematic diagrames of a seamless channel change, and this system 400 comprises an AP 402 and a STA 404.This AP 402 comprises a channel-changing notifying device 410, and a channel-changing decision maker 412, and it is to be connected to this channel-changing notifying device 410.One channel-changing device 414 is to be connected to this channel-changing decision maker 412.One measurement request device 416 is to be connected to this channel-changing decision maker 412.One transmitter/receiver 418 is to be connected to this channel-changing notifying device 410, this channel-changing device 414 and this measurement request device 416.One antenna 420 is to be connected to this transmitter/receiver 418.

This STA 404 comprises a channel-changing notifying device 430, and a channel-changing decision maker 432, and it is to be connected to this channel-changing notifying device 430.One STA capability device 434 is to be connected to this channel-changing decision maker 432.One channel-changing device 436 is to be connected to this channel-changing decision maker 432.One transmitter/receiver 438 is to be connected to this channel-changing notifying device 430 and this channel-changing device 436.One measurement report device 440 is to be connected to this transmitter/receiver 438.One antenna 442 is to be connected to this transmitter/receiver 438.

This system 400 is following runnings.This channel-changing notifying device 410 in this AP 402 sends this channel-changing intent message to this STA 404, is to be handled by channel-changing notifying device 430 in STA 404.Change at a STA initial channel under the situation of request, this channel-changing notifying device 430 in this STA 402 at first sends this channel-changing request message to this AP 402, in AP 402 is to be handled by channel-changing notifying device 410.

After this STA 404 receives this channel-changing intent message, this channel-changing decision maker 432 in this STA 404 judges just whether this STA changes its channel, and this channel-changing decision maker 432 can insert the information that is stored in this STA capability device 434 and make decision with help.In case this channel-changing decision maker 432 is made the decision about this channel-changing, it just sends a signal to this channel-changing notifying device 430, and it can will determine (via this channel-changing response message) to be sent to this channel-changing notifying device 410 in this AP 402.If these STA 404 desires change its channel, just then this channel-changing decision maker 4332 sends a signal to this channel-changing device 436 to change this channel.

In this AP 402, this channel-changing decision maker 412 is in order to judge whether this AP will change its channel.As mentioned above, the channel-changing response message that this decision can be subjected to being received from this STA 404 influences.Making aspect this decision, this channel-changing decision maker 412 can be to these STA 404 requests, and it is to reach via measurement request device 416.According to the measurement request that is received from this AP 402, this STA 404 takes suitable measurement, and gives this AP 402 via these measurement report device 440 repayment.If these AP 402 desires change its channel, just this channel decision maker 412 sends a signal to channel-changing device 414 to change this channel.

Embodiment

A kind of have the method for seamless channel change among the WLAN of a STA and an AP one, and its step is to comprise: send a channel-changing intent message to this STA by this AP; Send a channel-changing response message to this AP by this STA, notify this STA of this AP whether will follow this channel-changing; Judge whether carry out channel-changing in this AP; And if result of determination is for being then to carry out a channel-changing.

According to described method elder generation's the last period, wherein this channel-changing response message comprises an affirmation, and it is to confirm that this channel-changing intent message is received.

According to previous two sections described methods wherein, wherein this execution in step also comprises following steps: send a channel-changing notification message to this STA by this AP; Go up this channel of change in this AP and this STA; And send a channel-changing by this STA and carry out message to this AP, it is the successful execution according to channel-changing.

According to first three one of them described method of section of elder generation, wherein this WLAN comprises and surpasses one STA, and this execution in step will consider the quantity of the STAs that can change channel before carrying out this channel-changing.

According to the described method of first previous paragraphs, wherein this WLAN only comprises a STA, and this determination step comprises following steps: whether carry out this channel-changing by this AP decision; If desire is carried out this channel-changing, send a channel-changing notification message to this STA by this AP; On this AP and this STA, change this channel.

According to the described method of previous arbitrary paragraph, its step also comprises: if this channel-changing is successfully finished, send a channel-changing by this STA and carry out message to this AP.

According to first three section of elder generation described method wherein, wherein this WLAN comprises and surpasses a STA, and this determination step comprises following steps: send a channel-changing intent message this STA extremely whenever by this AP; Whether support this channel-changing by this STA decision whenever; Send a channel-changing response message to this AP by every this STA; Judge whether carry out this channel-changing by this AP; If desire is carried out this channel-changing, send a channel-changing notification message this STA extremely whenever by this AP; And at this AP and whenever change this channel on this STA.

According to previous four sections described methods wherein, its step also comprises: if this channel-changing is successfully finished, send a channel-changing by every this STA and carry out message to this AP.

A kind ofly comprise the system that carries out a seamless channel change among the WLAN of an AP and a STA one.This AP is configured to send a channel-changing intent message to this STA.This STA is configured to send a channel-changing response message to this AP, and this channel-changing response message comprises an indication, and it is whether this STA of indication will follow the new channel of this AP to one.This AP also be configured to receive this channel-changing respond news existing after, judge whether change its channel, and if be judged to be and be, just change its channel.

According to described system the last period, wherein this channel-changing response message comprises an affirmation, and it is to confirm that this channel-changing intent message is received by this STA.

According to previous two sections one section described systems wherein, if wherein this AP decision changes its channel, then this AP more is configured to send a channel-changing notification message to this STA and change its channel; And this STA more is configured to change its channel, and sends a channel-changing and carry out message to this AP, and it is the successful execution according to channel-changing.

According to first three one of them described system of section of elder generation, wherein this WLAN comprises and surpasses one STA, and this AP will consider the quantity of the STAs that can change channel before carrying out this channel-changing.

A kind ofly comprise the system that carries out a seamless channel change among the WLAN of an AP and a STA one.This STA is configured to send a channel-changing request message to this AP.This AP is configured to judge whether can carry out this channel-changing, and carries out this channel-changing based on this decision.

According to the described method, system of first previous paragraphs, wherein this WLAN only comprises a STA; If desire is carried out this channel-changing, send a channel-changing notification message to this STA by this AP; This AP is configured to change its channel; And this STA is configured to change its channel.

According to previous two sections one of them described systems, if wherein this channel-changing is successfully finished, this STA also is configured to send a channel-changing and carries out message to this AP.

According to first three one of them described system of section of elder generation, wherein this WLAN comprises and surpasses a STA; This AP is configured to send a channel-changing intent message this STA extremely whenever; Whenever this STA is configured to decision whether to support this channel-changing, and sends a channel-changing response message to this AP; This AP is configured to judge whether carry out this channel-changing, and if desire carry out this channel-changing, just send a channel-changing notification message, and change its channel to every this STA; And whenever this STA is configured to change its channel.

According to previous four sections one of them described methods, if wherein this channel-changing is successfully finished, whenever this STA more is configured to send a channel-changing and carries out message to this AP.

A kind ofly comprise the system that carries out a seamless channel change among the WLAN of an AP and a STA one.This AP comprises one first channel-changing notifying device; One first channel-changing decision maker, it is to be connected to this first channel-changing notifying device; One first channel-changing device, it is to be connected to this first channel-changing decision maker; One measurement request device, it is to be connected to this first channel-changing decision maker; One first transmitter/receiver, it is to be connected to this first channel-changing notifying device, this first channel-changing device and this measurement request device; And one first antenna, it is to be connected to this first transmitter/receiver.This STA comprises a second channel and changes notifying device; One second channel changes decision maker, and it is to be connected to this second channel to change notifying device; One platform capability device, it is to be connected to this second channel to change decision maker; One second channel modifier, it is to be connected to this second channel to change decision maker; One second transmitter/receiver, it is to be connected to this second channel to change notifying device and this second channel modifier; One measurement report device, it is to be connected to this second transmitter/receiver; And one second antenna, it is to be connected to this second transmitter/receiver.

According to described system elder generation's the last period, wherein the first channel-changing notifying device of this in this AP is to be configured to send a channel-changing intent message to this platform.

According to previous two sections one of them described systems, wherein this second channel in this platform changes notifying device, is to be configured to receive this channel-changing intent message.

According to first three one of them described system of section of elder generation, wherein this second channel in this platform changes notifying device, is to be configured to send a channel-changing request message to this AP.

According to previous four sections one of them described systems, wherein the first channel-changing notifying device of this in this AP is to be configured to receive this channel-changing request message.

According to the first five one of them described system of section of elder generation, wherein the first channel-changing decision maker of this in this AP is to be configured to judge whether this AP will change its transmission channel.

According to the first six one of them described system of section of elder generation, if wherein this AP will change its transmission channel, just then this first channel-changing decision maker sends a signal to this first channel-changing device, to change this transmission channel.

According to the first seven one of them described system of section of elder generation, wherein the first channel-changing decision maker of this in this AP sends a signal to this measurement request device, to measure to this platform request.

According to the first eight one of them described system of section of elder generation, wherein this measurement report device is to be configured to carry out measurement and to report that this measurement is to this AP.

According to previous nine sections one of them described systems, wherein this second channel in this platform changes decision maker, is to be configured to judge whether this platform will change its receive channel.

According to previous ten sections one of them described systems, if wherein this platform will change its receive channel, just then this second channel change decision maker sends a signal to this second channel modifier, to change this receive channel.

Demonstration Application of the present invention has comprised the field of load balance and dynamic channel selection, in these are used, needs this AP to change its channel and has become time dependent load of adaptation and disturbance state.The present invention allows to interrupt carrying out this kind channel-changing with the minimum service of the STAs that links to each other.

Although feature of the present invention and element are all described in the particular combinations mode in embodiment, but each feature or element can use alone among the embodiment, and do not need other features or elements combination with better embodiment, or with/do not do different combinations with other features of the present invention and element.Although the present invention describes by preferred embodiment, the modification of desorption the application claim scope is not conspicuous concerning person skilled in the art scholar for other.Above-mentioned description is for the purpose of description, and can not limit special invention by any way.

Claims

1. method of in a Wireless LAN (WLAN), carrying out a seamless channel change, this Wireless LAN has a base station (STA) and an access point (AP), and its step comprises:

Send a channel-changing intent message to this STA from this AP;

Send a channel-changing response message to this AP from this STA, notify this STA of this AP whether can follow this channel-changing;

At this this channel-changing of AP decision whether carrying out; And

If this determines then to carry out a channel-changing into just.

2. method according to claim 1 is characterized in that this channel-changing response message comprises an affirmation, and it is to confirm that this channel-changing intent message is received.

3. method according to claim 1 is characterized in that this execution in step comprises:

Send a channel-changing notification message to this STA from this AP;

Changing this channel on this AP and on this STA; And

After this channel-changing is successfully carried out, send a channel-changing from this STA immediately and carry out message to this AP.

4. method according to claim 1 is characterized in that this WLAN comprises more than one STA, and this execution in step can be considered the STA quantity that can change channel before carrying out this channel-changing.

5. method of in a Wireless LAN (WLAN), carrying out a seamless channel change, this Wireless LAN has a base station (STA) and an access point (AP), and its step comprises:

Send a channel-changing request message to this AP from this STA;

Determine whether this can carry out this channel-changing; And

Determine to carry out this channel-changing according to this.

6. method according to claim 5 it is characterized in that this WLAN only comprises a STA, and this deciding step comprises:

Determine whether this channel-changing will be performed by this AP;

If in the time of will carrying out this channel-changing, then send a channel-changing notification message to this STA from this AP; And

On this AP and this STA, change this channel.

7. method according to claim 6 is characterized in that its step also comprises:

If successfully carried out this channel-changing, then send a channel-changing and carry out message to this AP from this STA.

8. method according to claim 5 it is characterized in that this WLAN comprises more than one STA, and this deciding step comprises:

Send a channel-changing intent message to each STA from this AP;

Determine whether this channel-changing can be supported by each STA;

Send a channel-changing response message to this AP from each STA;

Determine whether this channel-changing will be performed by this AP;

If will carry out this channel-changing, then send a channel-changing notification message to each STA from this AP;

At this AP and whenever change this channel on this STA.

9. method according to claim 8 is characterized in that its step also comprises:

If successfully carried out this channel-changing, then send a channel-changing and carry out message to this AP from each STA.

10. system that in a Wireless LAN (WLAN), carries out a seamless channel change, it comprises:

One access point (AP);

One platform (STA);

This AP is configured to send a channel-changing intent message to this STA;

This STA is configured to send a channel-changing response message to this AP, and this channel-changing response message comprises an indication, and it is whether this STA of indication will follow the new channel of this AP to one; And

This AP is configured to after receiving this channel-changing response message, and whether decision changes its channel, and if this determine then to change its channel into just.

11. system according to claim 10 is characterized in that this channel-changing response message comprises an affirmation, it is to confirm that this channel-changing intent message is received by this STA.

12. system according to claim 10 is characterized in that if this AP decision changes its channel, then:

This AP also is configured to send a channel-changing notification message to this STA and change its channel; And

This STA also is configured to change its channel, and after successfully carrying out this channel-changing, sends a channel-changing immediately and carry out message to this AP.

13. system according to claim 10 is characterized in that this WLAN comprises more than one STA, and before carrying out this channel-changing, this AP can consider the STA quantity that can change channel.

14. a system that carries out a seamless channel change in a Wireless LAN (WLAN), it comprises:

One access point (AP);

One platform (STA);

This STA is configured to send a channel-changing request message to this AP; And

This AP is configured to determine whether this channel-changing can be carried out, and carries out this channel-changing according to this decision.

15. system according to claim 14 is characterized in that:

This WLAN only comprises a STA;

If will carry out this channel-changing, then this AP sends a channel-changing notification message to this STA;

This AP is configured to change its channel; And

This STA is configured to change its channel.

16. system according to claim 15 also is configured to when successfully carrying out this channel-changing if it is characterized in that this STA, then sends a channel-changing and carries out message to this AP.

17. system according to claim 14 is characterized in that:

This WLAN comprises more than one STA;

This AP is configured to send a channel-changing intent message to each STA;

Each STA is configured to determine whether this channel-changing can be supported, and sends a channel-changing response message to this AP;

This AP is configured to decision whether will carry out this channel-changing, and if will carry out this channel-changing, then send a channel-changing notification message to each STA, and change its channel; And

Each STA is configured to change its channel.

18. system according to claim 17 is characterized in that if successfully carried out this channel-changing, then each STA also is configured to send a channel-changing and carries out message to this AP.

19. a system that carries out a seamless channel change in a Wireless LAN, it comprises:

One access point, it comprises:

One first channel-changing notifying device;

One first channel-changing decision maker, it is connected to this first channel-changing notifying device;

One first channel-changing device, it is connected to this first channel-changing decision maker;

One measurement request device, it is connected to this first channel-changing decision maker;

One first transmitter/receiver, it is connected to this first channel-changing notifying device, this first channel-changing device and this measurement request device; And

One first antenna, it is connected to this first transmitter/receiver; And

One platform, it comprises:

One second channel changes notifying device;

One second channel changes decision maker, and it is connected to this second channel and changes notifying device;

One platform capability device, it is connected to this second channel and changes decision maker;

One second channel modifier, it is connected to this second channel and changes decision maker;

One second transmitter/receiver, it is connected to this second channel and changes notifying device and this second channel modifier;

One measurement report device, it is connected to this second transmitter/receiver; And

One second antenna, it is connected to this second transmitter/receiver.

20. system according to claim 19 is characterized in that this first channel-changing notifying device in this AP, is to be configured to send a channel-changing intent message to this platform.

21. system according to claim 20 is characterized in that this second channel in this platform changes notifying device, is to be configured to receive this channel-changing intent message.

22., it is characterized in that this second channel in this platform changes notifying device, be to be configured to send a channel-changing request message to this AP according to claim 19 or 20 described systems.

23. system according to claim 22 is characterized in that this first channel-changing notifying device in this AP, is to be configured to receive this channel-changing request message.

24., it is characterized in that this first channel-changing decision maker in this AP, be to be configured to judge whether this AP will change its transmission channel according to claim 19,20 or 22 described systems.

25. system according to claim 24 is characterized in that if this AP will change its transmission channel then this first channel-changing decision maker just sends a signal to this first channel-changing device, to change this transmission channel.

26. according to claim 19,20,22 or 24 described systems, it is characterized in that this first channel-changing decision maker in this AP sends a signal to this measurement request device, to measure to this platform request.

27., it is characterized in that this measurement report device is to be configured to carry out measurement and to report that this measurement is to this AP according to claim 19,20,22,24 or 26 described systems.

28., it is characterized in that this second channel in this platform changes decision maker, be to be configured to judge whether this platform will change its receive channel according to claim 19,20,22,24 or 26 described systems.

29. system according to claim 28 is characterized in that if this platform will change its receive channel, this second channel changes decision maker and just sends a signal to this second channel modifier, to change this receive channel.