CN100450057C - Wireless station point switching method and radio inserting point thereof - Google Patents

Wireless station point switching method and radio inserting point thereof Download PDF

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Publication number
CN100450057C
CN100450057C CNB2005101033183A CN200510103318A CN100450057C CN 100450057 C CN100450057 C CN 100450057C CN B2005101033183 A CNB2005101033183 A CN B2005101033183A CN 200510103318 A CN200510103318 A CN 200510103318A CN 100450057 C CN100450057 C CN 100450057C
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sta
tap
handoff request
message
cap
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CN1933435A (en
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李鸿飞
庄宏成
杜汉美
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XFusion Digital Technologies Co Ltd
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Huawei Technologies Co Ltd
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Abstract

A method for switching over radio station includes sending switch-over request message to object radio access point by radio station, feeding back switch-over and wait message to radio station by object radio access point, returning radio station to channel of current radio access point and carrying out communication with current radio access point then carrying out relevant treatment of switching over course according to switch-over request response message feedback by object radio access point through current radio access point on channel of current radio access point. The radio access point used in said method is also disclosed.

Description

The changing method of wireless site and WAP (wireless access point) thereof
Technical field
The present invention relates to WLAN (wireless local area network) (WLAN, Wireless Local Area Network) technical field, especially relate to a kind of changing method and WAP (wireless access point) thereof of wireless site.
Background technology
At present, at WLAN (wireless local area network) (WLAN, Wireless Local Area Network) in, wireless site (STA, Station) at different radio access point (AP, Access Point) method of switching between is: at STA and current wireless access point (CAP, Current Access Point) communicate during, in the time of need switching to other AP and get on, STA at first disconnects and the connecting of current wireless access point CAP, send handoff request to Target Wireless access point (TAP, Target Access Point) again, the correlation behavior information of application respective resources and transmission self on Target Wireless access point TAP; Treat to notify this STA handoff procedure of current wireless access point CAP to finish by Target Wireless access point TAP behind the STA handover success.
Please refer to Fig. 1, this figure is in existing IEEE802.11r draft, STA carries out the process schematic diagram of hand-off process between diverse access point AP, in the IEEE802.11r draft standard, the main process of carrying out hand-off process between the different AP of STA in WLAN (wireless local area network) is as follows:
Al, STA are measured to and need leave current wireless access point CAP, and set up session with Target Wireless access point TAP;
A2, STA change the channel of TAP over to, to send 802.11 authentication request to TAP;
A3, because the IEEE802.11r draft standard will be to the fail safe and the service quality (QoS of communication when emphasizing that STA carries out hand-off process between different AP, Quality Of Service) considers, like this when TAP receives 802.11 authentication request message of being sent by STA, TAP is when handling the authentication request of STA, need hold consultation with the upper strata of key level and other a plurality of network elements, and after handling the authentication request of sending by STA, feed back 802.11 authentication request to STA and reply;
After a4, STA receive 802.11 authentication request successful respond of TAP feedback, send reassociation requests to TAP again; Wherein in reassociation requests, STA can be to the TAP requests resource allocation;
After a5, TAP receive the reassociation requests that STA sends, after handling through consultation, be that STA reserves Resources allocation, reply to STA feedback reassociation requests then with a plurality of network elements.
So far, STA successfully switches to Target Wireless access point TAP from current wireless access point CAP, and after this STA just can carry out secured session and data interaction with TAP.
But in above-mentioned handoff process, after TAP need hold consultation with other a plurality of network elements with the upper strata of key level (key generation system), to determine attributes such as required key and resource, could reply 802.11 authentication request to STA to reply, with fail safe and the QoS that guarantees to communicate by letter; And TAP and upper layer network element are held consultation and handle to be are needed the cost certain hour, promptly between this period of negotiation, because TAP is the authentication request of treatment S TA in time, can cause STA in the channel of TAP, to be in wait state, cause switching and time delay occurs, and because current STA has left the channel of CAP, but do not carry out exchanges data with TAP, so also can cause the packet data loss in the communication process, have a strong impact on thereby may cause to real time communication business (as packet voice VOIP business).
At the defect problem that exists in the above-mentioned handoff procedure, the correspondence problem that exists in to above-mentioned handoff procedure in " ' wait ' of switching fast in the authentication message replys (" Not Ready " Response in FT Auth Messages (11-05-0829-00-000r)) " motion improves.
Please refer to Fig. 2, this figure is the STA that proposes in " Not Ready " Response in FT Auth Messages motion carries out hand-off process between diverse access point AP a process schematic diagram; In " Not Ready " Response in FT Auth Messages motion, the main process of carrying out hand-off process between the different AP of STA in WLAN (wireless local area network) is as follows:
B1, STA need leave current wireless access point CAP carrying out being measured in session and the data exchange process with current wireless access point CAP, and set up session with Target Wireless access point TAP;
B2, STA change the channel of TAP over to, to send 802.11 authentication request to TAP;
B3, TAP are after receiving 802.11 authentication request that STA sends, if the timely authentication request of treatment S TA, TAP can estimate the authentication request required time length of treatment S TA, promptly estimate to finish with the upper layer network element and hold consultation to determine STA is carried out the time span of the required key information of Certificate Authority, sending authentication request to STA then waits for the arrival of news, STA waits for indication, and wherein TAP this time of carrying TAP in the authentication request that STA sends waits for the arrival of news estimates to handle the time span value that obtains;
B4, STA receive after this authentication request of require waiting for waits for the arrival of news, and return in the channel of CAP and continue and CAP carries out session and data interaction;
Length value estimated time of carrying during b5, STA wait for the arrival of news according to the authentication request that receives, in that passed through should estimated time behind the length value, turn back to the authentication response of waiting for TAP in the channel of TAP once more, or turn back in the channel of TAP again to TAP and retransmit 802.11 authentication request (among the figure shown in the dotted line);
B6, TAP finish negotiation with the upper layer network element, after having determined STA carried out the needed key information of Certificate Authority, feed back 802.11 authentication request to STA again and reply;
After b7, STA receive 802.11 authentication request successful respond of TAP feedback, send reassociation requests to TAP again, with to the TAP requests resource allocation;
After b8, TAP receive the reassociation requests that STA sends, if the timely reassociation requests of treatment S TA, TAP can estimate the reassociation requests required time length of treatment S TA, promptly estimate to finish with the upper layer network element and hold consultation to determine time span to the Internet resources of STA distribution, sending reassociation requests to STA then waits for the arrival of news, STA waits for indication, and wherein TAP carries the time span value that this time of TAP estimates that processing obtains in the reassociation requests that STA sends waits for the arrival of news;
B9, STA receive after this reassociation requests of require waiting for waits for the arrival of news, and return in the channel of CAP and continue and CAP carries out session and data interaction;
Length value estimated time of carrying during b10, STA wait for the arrival of news according to the reassociation requests that receives, in that passed through should estimated time behind the length value, turn back to the reassociation requests of waiting for TAP in the channel of TAP once more and reply, or turn back in the channel of TAP again to TAP and retransmit reassociation requests (among the figure shown in the dotted line);
B11, TAP finish negotiation with the upper layer network element, after having determined to distribute to the Internet resources of STA, reply to STA feedback reassociation requests again;
So far, STA successfully switches to Target Wireless access point TAP from current wireless access point CAP, and after this STA just can carry out secured session and data interaction with TAP.
This shows, the hand-off process mode that above-mentioned motion proposes, Target Wireless access point TAP will carry out twice time and estimate to handle, for the first time be after receiving the authentication request that STA sends, estimate to hold consultation to determine STA is carried out the time span value of the key information of Certificate Authority with the upper layer network element; For the second time be after receiving the reassociation requests that STA sends, estimate to hold consultation with the time span value of the Internet resources of determining to distribute to STA with the upper layer network element; But because TAP needs and upper strata and other a plurality of network elements of key level are held consultation, to determine the key information and the network resource information of correspondence.But generally, the upper strata of key level and the state of other network element may change along with the variation of time, thereby the processing time length value that may cause TAP to estimate after consulting prolongs or shortens, and TAP also may be because other unpredictable factor be [unusual as the unexpected short time of self system, with distributed system (DS, Distribution System) communication data is made mistakes, or the situation such as withdraw from of other STA] and the processing time length value that causes self estimating prolongs or shortens, so the accuracy of the processing time length value of being estimated by TAP is very unreliable.
Like this, the processing time length value of being estimated by TAP that STA obtains also is inaccurate, therefore work as the time span value that STA receives according to self, after through corresponding estimation duration, STA leaves the channel of CAP, change over to and continue in the channel of TAP to wait for or re-send request may (authentication request or reassociation requests), the request of STA but TAP this moment may still can't finish dealing with, so the time of can carrying out is once more estimated, and send correspondence to STA and wait for the arrival of news, thereby increased a wait process once more, therefore increased the handover delay of STA.Bide one's time waiting once more simultaneously, STA also can turn back in the channel of CAP and continue and CAP communicates, like this when waiting for that the number of times occurrence probability is when higher, can cause STA between CAP and TAP, to carry out " table tennis switches " effect, thereby the packet data loss probability in the communication process is increased, and this can cause relatively the real time communication business and seriously influence.
Summary of the invention
The technical problem to be solved in the present invention is to propose a kind of changing method of wireless site, reducing handover delay, and reduces the losing probability of grouped data, avoids that communication service impacts to real-time.
Accordingly, the invention allows for a kind of WAP (wireless access point).
For addressing the above problem, the technical scheme that the present invention proposes is as follows:
A kind of changing method of wireless site comprises step:
A, wireless site STA send handoff request message to Target Wireless access point TAP;
B, described TAP wait for the arrival of news to the switching of STA feedback;
Channel and CAP that C, described STA return current wireless access point CAP communicate; And
D, basis receive on described CAP channel by described TAP feeds back the handoff request acknowledgment message situation of coming by CAP, carries out the alignment processing in the handoff procedure;
E1, be the handoff request success message in the handoff request acknowledgment message that receives, and the handoff request process is when finishing, channel and TAP that described STA is transferred to TAP communicate, the handoff procedure of end from described CAP to TAP.
Preferably, STA is communicating in the process with described CAP in the described steps A, when being measured to described TAP signal strength signal intensity and being satisfied with switching condition with respect to the CAP signal strength signal intensity, is transferred to the TAP channel and sends handoff request message to TAP.
Preferably, also comprise step between described steps A and the B:
When A-1, described TAP receive the handoff request message that STA sends, judge whether in time to handle this handoff request message, if, execution in step A-2; Otherwise execution in step B;
A-2, described TAP are to the corresponding handoff request acknowledgment message of described STA feedback;
A-3, described STA judge whether the handoff request process finishes, if, on the channel of described TAP, communicate with TAP, finish handoff procedure from described CAP to TAP; Otherwise
A-4, return the described STA of steps A and continue to send follow-up handoff request message to TAP.
Preferably, the process that STA receives the handoff request acknowledgment message of being come by CAP feedback by TAP among the described step D on the CAP channel specifically comprises:
When D1, described TAP handle the handoff request message that STA sends, generate corresponding handoff request acknowledgment message, and be that described handoff request acknowledgment message encapsulates the address of CAP and the address of STA;
D2, the described TAP handoff request acknowledgment message after with encapsulation process sends to distributed system;
D3, described distributed system are forwarded to described CAP according to the CAP address of carrying in the handoff request acknowledgment message that receives with described handoff request acknowledgment message;
D4, described CAP are transmitted to STA according to the STA address of carrying in the handoff request acknowledgment message that receives with described handoff request acknowledgment message.
Preferably, also comprise before the described step e 1:
Described STA preestablishes the expected time length value of the described TAP feedback of expectation handoff request acknowledgment message; And judge whether in the expected time length value that sets, to receive the handoff request acknowledgment message that TAP comes by the CAP feedback, if, execution in step E1; Otherwise STA thinks the failure of this handoff request, returns steps A and continues to send this handoff request message to TAP.
Preferably, after described step D, also comprise:
E2, be the handoff request success message, and the handoff request process is returned the described STA of steps A and is continued to send follow-up handoff request message to TAP when not finishing in the handoff request acknowledgment message that receives.
Preferably, also comprise before the described step e 2:
Described STA preestablishes the expected time length value of the described TAP feedback of expectation handoff request acknowledgment message; And judge whether in the expected time length value that sets, to receive the handoff request acknowledgment message that TAP comes by the CAP feedback, if, execution in step E2; Otherwise STA thinks the failure of this handoff request, returns steps A and continues to send this handoff request message to TAP.
Preferably, after described step D, also comprise:
E3, when the handoff request acknowledgment message that receives is the handoff request failed message, return the described STA of steps A and continue to send this handoff request message to TAP.
Preferably, also comprise before the described step e 3:
Described STA preestablishes the expected time length value of the described TAP feedback of expectation handoff request acknowledgment message; And
Judge whether in the expected time length value that sets, to receive the handoff request acknowledgment message that TAP comes by the CAP feedback, if, execution in step E3; Otherwise,
STA thinks the failure of this handoff request, returns steps A and continues to send this handoff request message to TAP.
Preferably, described STA is authentication request message and reassociation requests message to the handoff request message that TAP sends successively; Described TAP waits for the arrival of news to the switching of STA feedback, and authentication request for the authentication request message of the described transmission of correspondence waits for the arrival of news and the reassociation requests of the reassociation requests message of corresponding described transmission waits for the arrival of news; Described TAP is the reassociation requests response message of the reassociation requests message of the authentication request response message of authentication request message of corresponding described transmission and corresponding described transmission to the handoff request acknowledgment message that is in the STA feedback on the CAP channel by CAP.
A kind of WAP (wireless access point) comprises:
The unit is known in the address, is used for the handoff request message sent according to wireless site STA, knows the address information of the current wireless access point CAP at the address information of described STA and this STA place;
The response message generation unit is used for after the handoff request message that described STA is sent is handled, and generates corresponding handoff request acknowledgment message;
The address encapsulation unit is used for knowing the address information that the unit gets access to according to described address, encapsulates the CAP address at this STA address and this STA place for the handoff request acknowledgment message of described response message generation unit generation;
The response message transmitting element, be used for the handoff request acknowledgment message after the encapsulation unit encapsulation process of described address is sent to distributed system, so that distributed system is forwarded to CAP according to the CAP address in the handoff request acknowledgment message with handoff request acknowledgment message, and make CAP handoff request acknowledgment message is transmitted to STA according to the STA address in the handoff request acknowledgment message.
The beneficial effect that the present invention can reach is as follows:
The present invention program sends handoff request message by STA to TAP; TAP switches to the STA feedback and to wait for the arrival of news under the situation of the handoff request message that timely treatment S TA sends; STA receive switch wait for the arrival of news after, the channel and the CAP that return CAP communicate; And follow-up basis receives the handoff request acknowledgment message situation of being come by CAP feedback by TAP on the CAP channel, carries out the alignment processing in the handoff procedure.Thereby can avoid in the prior art STA in order to receive the handoff request acknowledgment message that TAP sends, wait for or retransmit handoff request message, therefore can reduce STA carries out hand-off process between CAP and TAP time delay and need constantly return the TAP channel; Simultaneously can also avoid STA in order on the TAP channel, to receive the handoff request acknowledgment message of sending by TAP, and need continuous interchannel to switch at CAP and TAP, do not wish " table tennis switches " effect of taking place and produce handoff procedure, therefore can reduce the packet data loss probability that causes owing to " table tennis switches " effect in the communication process, the corresponding communication quality that improves the real-time communication service.
Simultaneously, TAP no longer needs the needed concrete duration value of handoff request of estimating that treatment S TA sends in handoff process, corresponding STA also no longer needs to monitor the estimation duration value that TAP returns, and has therefore reduced the processing complexity of wireless access point AP and wireless site STA.
Description of drawings
Fig. 1 is that STA carries out the process schematic diagram of hand-off process between diverse access point AP in existing IEEE802.11r draft;
Fig. 2 carries out the process schematic diagram of hand-off process between diverse access point AP for the STA that proposes in " Not Ready " Response in FT Auth Messages motion;
Fig. 3 is the main realization principle flow chart of the changing method of wireless site of the present invention;
Fig. 4 judges whether to send the process chart that switching waits for the arrival of news to STA for TAP in the inventive method;
Fig. 5 is that STA carries out the particular flow sheet of alignment processing according to the situation of TAP by CAP feedback handoff request acknowledgment message in the inventive method;
The processing procedure schematic diagram that Fig. 6 implements in the wlan system structure of existing standard for the inventive method;
Fig. 7 is principle according to the proposed method, and STA carries out the process schematic diagram of hand-off process between diverse access point AP;
Fig. 8 is the main composition structured flowchart of wireless access point AP of the present invention.
Embodiment
In the tradition of the WAP (wireless access point) among WLAN switching mode, STA leaves the channel of CAP, be transferred to the channel of TAP and send handoff request message to TAP, in the time of may having because the timely handoff request of treatment S TA of TAP, therefore TAP can estimate to handle the needed duration of handoff request of this STA, then the duration value of estimating to obtain is carried on to switch and sends to STA in waiting for the arrival of news, STA waits for indication.After STA receives this wait message, return to and continue in the channel of CAP to carry out session and exchanges data with CAP, after having passed through a period of time that equates with the duration value of TAP estimation, be transferred to again in the channel of TAP and retransmit handoff request message, or be transferred in the channel of TAP and wait for the handoff request acknowledgment message that receives the TAP feedback to TAP.Because when TAP estimate to handle the required duration value of handoff request, often to take all factors into consideration multiple factors such as QoS, safety and resource allocation, promptly will hold consultation, so the duration value accuracy of estimating in the actual process is not very high with upper strata and other a plurality of network elements of key level.STA is after having waited for the duration value of being estimated by TAP, be transferred to again in the channel of TAP, might not in time receive the handoff request acknowledgment message of TAP this moment, if this moment, TAP did not still handle the handoff request that STA sends, can send to STA once more and require its equivalent messages of waiting for, so STA needs to wait for once more.As mentioned above, STA need switch through the interchannel of the channel of the CAP that is everlasting and TAP and repeatedly wait for back and forth, thereby increased the packet data loss probability in the communication process and the time delay of hand-off process.The present invention program has proposed STA and has carried out in the handoff procedure between CAP and TAP thus, STA is receiving after switching that TAP sends waits for the arrival of news, turn back on the channel of CAP and communicate with CAP, on the channel of CAP, wait for simultaneously and receive the handoff request acknowledgment message that TAP sends by CAP, and, carry out the alignment processing of handoff procedure according to receiving the situation of TAP by CAP transmission handoff request acknowledgment message.To avoid STA in handoff procedure, need constantly to switch back and forth and repeatedly wait at the channel of CAP and the interchannel of TAP, reduced handover delay, and reduced the losing probability of grouped data, the corresponding communication quality that improves the real-time communication service.
Below in conjunction with each accompanying drawing main realization principle of the present invention and embodiment thereof are explained in detail.
Please refer to Fig. 3, this figure is the main realization principle flow chart of the changing method of wireless site of the present invention, and its main implementation procedure is as follows:
Step S10, wireless site STA sends handoff request message to Target Wireless access point TAP; Wherein STA is communicating in the process with current wireless access point CAP, if when being measured to the signal strength signal intensity of Target Wireless access point TAP and being satisfied with switching condition with respect to the signal strength signal intensity of CAP, the channel that just is transferred to TAP sends handoff request message to TAP.
Wherein STA is being carried out in the handoff procedure to TAP by CAP, and successively the handoff request message of Fa Songing is drawn together IEEE802.11 authentication request message and reassociation requests message.
When step S20, TAP receive the handoff request message of being sent by STA, wait for the arrival of news to the switching of STA feedback;
Please refer to Fig. 4, this figure is that TAP judges whether to send the process chart that switching waits for the arrival of news to STA in the inventive method, and its main implementation procedure is as follows:
Step S11, TAP receives the handoff request message that STA sends;
Step S12, TAP judge whether this handoff request message that timely treatment S TA sends, if, execution in step S13; Otherwise execution in step S14 (being above-mentioned steps S20);
Step S13, TAP in time finish dealing with after the handoff request message that STA sends, to the corresponding handoff request acknowledgment message (as IEEE802.11 authentication request response message and reassociation requests response message etc.) of STA feedback, execution in step S15 then;
Step S14, TAP switch and wait for the arrival of news (waiting for the arrival of news and reassociation requests waits for the arrival of news etc. as the IEEE802.11 authentication request) to STA feedback, carry out other processing procedures after waiting for the arrival of news then.
Step S15, STA judge whether the handoff request process finishes, if, execution in step S16; Otherwise execution in step S17;
Step S16, STA communicates with TAP on the channel of TAP, finishes the handoff procedure from CAP to TAP;
Step S17, (returning above-mentioned steps S10) STA continue to send follow-up handoff request message (for example above-mentioned processing procedure is the processing procedure to authentication request message, and then follow-up STA can continue to send reassociation requests message to TAP) to TAP.
Please continue with reference to the step S30 among Fig. 3, STA receives after the switching that is come by TAP feedback waits for the arrival of news, and the channel that turns back to current wireless access point CAP is proceeded to communicate by letter with CAP;
Step S40, follow-up, STA can feed back the handoff request acknowledgment message situation of coming by CAP according to receiving by TAP on the CAP channel, carry out the alignment processing in the handoff procedure.
Wherein STA receives by TAP specific as follows by the process of the next handoff request acknowledgment message of CAP feedback on the CAP channel:
When 1) TAP handles the handoff request message that STA sends, generate corresponding handoff request acknowledgment message, and be the address of the handoff request acknowledgment message encapsulation CAP that generates and the address of STA;
2) then, the handoff request acknowledgment message of TAP after with encapsulation process sends to distributed system (DS, Distribution System);
3) DS is forwarded to corresponding CAP according to the CAP address information of carrying in the handoff request acknowledgment message that receives with handoff request acknowledgment message;
4) this CAP continues to be transmitted to this STA according to the STA address of carrying in the handoff request acknowledgment message that receives with handoff request acknowledgment message.
Please refer to Fig. 5, this figure is that STA carries out the particular flow sheet of alignment processing according to the situation of TAP by CAP feedback handoff request acknowledgment message in the inventive method, and its concrete alignment processing process is as follows:
Step S41, STA preestablish the expected time length value (as the handoff request acknowledgment message of expectation TAP in 1ms internal feedback correspondence is set) of expectation TAP feedback handoff request acknowledgment message;
Step S42, STA turns back in the process that communicates with CAP on the channel of CAP, judge whether simultaneously in the expected time length value that sets, to receive the handoff request acknowledgment message that TAP comes by the CAP feedback, if, execution in step S43 or step S47; Otherwise execution in step S48;
Step S43, the handoff request acknowledgment message that TAP comes by the CAP feedback is the handoff request success message;
Step S44, STA judge whether the handoff request process finishes, if, execution in step S45; Otherwise execution in step S46;
The channel that step S45, STA are transferred to TAP sends handoff request success response message to TAP, and communicates with TAP on the channel of TAP, thereby finishes whole handoff process from CAP to TAP.
Step S46, (returning above-mentioned steps S10) STA continues (for example to send follow-up handoff request message to TAP on the channel of TAP, if above-mentioned processing procedure is at authentication request message, then here STA can continue to send reassociation requests message to TAP, finishes until handoff process).
Step S47, the handoff request acknowledgment message that TAP comes by the CAP feedback is the handoff request failed message;
Step S48, STA can think the failure of this handoff request, (returning above-mentioned steps S10) STA can continue to send this handoff request message (if promptly above-mentioned processing procedure is that then STA can continue to send this authentication request message to TAP at authentication request message) here to TAP.
802.11 authentication request message and reassociation requests message that wherein corresponding STA sends, TAP can be by CAP to corresponding authentication request response message and the reassociation requests response message of STA feedback.
Following is an embodiment who implements the inventive method:
The wlan system that the inventive method was relied on when implementing is identical with the IEEE802.11 system configuration of existing standard, specifically please refer to shown in Figure 6, by distributed system (DS), WAP (wireless access point) (AP) and wireless site (STA) composition.In WLAN, STA is connected with DS by AP, thereby realization and WLAN communication equipment interior or that WAN is interior communicates.On the wlan system architecture basics of this standard, the main implementation process of the inventive method is as follows:
1. STA communicates by CAP and DS;
2. STA is switched on the TAP by CAP at needs, when realizing communicating by letter by TAP and DS, sends handoff request to TAP;
If 3. the TAP handoff request that STA sends of in time finishing dealing with then sends the handoff request successful respond to STA; If TAP is because longer with other network element required time of holding consultation, and during the handoff request that the STA that can not in time finish dealing with sends, can send a switching to STA to wait for the arrival of news, require STA to wait for;
4. STA receives the switching that TAP sends and waits for the arrival of news, and turns back in the channel of CAP to continue to communicate with CAP, and waits for that TAP replys by the handoff request that CAP sends;
If STA replys by the handoff request that CAP sends at the overtime TAP that do not receive yet of the expected time of self 4., then judge the failure of this handoff request, and return above-mentioned the transmission to TAP once more in 2. should be with a handover request message.
5. after TAP finishes dealing with the handoff request that STA sends, send corresponding handoff request by DS to CAP and reply, CAP replys this handoff request and is transmitted to STA;
If to reply be the handoff request failure to the handoff request that receives of STA 5., then STA be back to above-mentioned the transmission to TAP once more in 2. should be with a handover request message.
Be the handoff request success if the handoff request that STA receives is 5. replied, then change over to and carry out next step processing;
If 6. whole handoff request processing procedure (comprising authentication request procedure and reassociation requests process etc.) finishes, then STA is transferred to the channel of TAP sends response from the handoff request successful respond to TAP; Otherwise turning back to the above-mentioned 2. middle follow-up handoff request of carrying out in the handoff procedure handles.
7. STA realize by TAP on the TAP channel with DS between communicate by letter.
Please refer to Fig. 7, this figure is a principle according to the proposed method, and STA carries out the process schematic diagram of hand-off process between diverse access point AP, and the main process of carrying out hand-off process between the different AP of STA in WLAN (wireless local area network) is as follows:
C1, STA need leave current wireless access point CAP carrying out being measured in session and the data exchange process with current wireless access point CAP, and set up session with Target Wireless access point TAP;
C2, STA are transferred to the channel of TAP, to send 802.11 authentication request to TAP;
C3, TAP are after receiving 802.11 authentication request that STA sends, if the timely authentication request of treatment S TA can send authentication request to STA and waiting for the arrival of news, STA waits for indication;
C4, STA receive after this authentication request of require waiting for waits for the arrival of news, and turn back in the channel of CAP and continue and CAP carries out session and data interaction;
C5, TAP feed back 802.11 authentication request and reply to being in STA on the CAP channel by CAP after 802.11 authentication request that the STA that finishes dealing with sends;
C6, STA are after receiving the 802.11 authentication request successful respond that TAP comes by CAP feedback on the channel of CAP, the channel that turns back to TAP again sends reassociation requests to TAP, with to the TAP requests resource allocation;
After c7, TAP received the reassociation requests that STA sends, if the timely reassociation requests of treatment S TA can send reassociation requests to STA and waiting for the arrival of news, STA waited for indication;
C8, STA receive after this reassociation requests of require waiting for waits for the arrival of news, and turn back in the channel of CAP and continue and CAP carries out session and data interaction;
C9, TAP reply to the STA feedback reassociation requests that is on the CAP channel by CAP after the reassociation requests that the STA that finishes dealing with sends;
C10, STA are after receiving the reassociation requests successful respond of TAP by the CAP feedback on the channel of CAP, the channel that turns back to TAP again is to TAP feedback reassociation requests success response message; So far, STA successfully switches to Target Wireless access point TAP from current wireless access point CAP, and after this STA just can carry out secured session and data interaction with TAP on the channel of TAP.
As fully visible, the changing method of wireless site of the present invention can avoid STA can not in time handle under the situation of handoff request at TAP, cause STA need on the channel of TAP, wait for or retransmit handoff request message, and avoided STA not receive handoff request that the TAP feedback comes when replying at waiting time, be in " table tennis switches " effect that the interchannel of the channel of CAP and TAP switches repeatedly, therefore reduced the time delay of handoff procedure, reduce the losing probability of packet data package in the handoff procedure simultaneously, relatively helped the development of real-time communication service.
Simultaneously in handoff process, TAP also no longer needs the needed concrete duration value of request message of estimating that treatment S TA sends, corresponding STA also no longer needs to monitor the estimation duration value that TAP returns, and has reduced the processing complexity of wireless access point AP and wireless site STA thus.
Accordingly, the invention allows for a kind of wireless access point AP, please refer to Fig. 8, this figure is the main composition structured flowchart of wireless access point AP of the present invention, it mainly comprises: unit 10, response message generation unit 20, address encapsulation unit 30 and response message transmitting element 40 are known in the address, and wherein the main effect of each part is as follows:
Unit 10 is known in the address, be mainly used in the handoff request message of sending according to wireless site STA (as comprising authentication request message and reassociation requests message etc.), know the address information of the current wireless access point CAP at the address information of STA and this present place of STA;
Response message generation unit 20 is mainly used in after the handoff request message that STA is sent is finished dealing with, and generates corresponding handoff request acknowledgment message (as comprising authentication request response message and reassociation requests response message etc.);
Address encapsulation unit 30 is mainly used in according to the address and knows the address information that unit 10 gets access to, and the handoff request acknowledgment message that generates for response message generation unit 20 encapsulates the corresponding STA address and the CAP address at this present place of STA;
Response message transmitting element 40, be mainly used in the handoff request acknowledgment message after address encapsulation unit 30 encapsulation process is sent to distributed system DS, so that DS can be according to the CAP address information that encapsulates in the handoff request acknowledgment message that receives, the handoff request acknowledgment message that receives is forwarded to CAP, and make CAP according to the STA address information that encapsulates in the handoff request acknowledgment message that receives, the handoff request acknowledgment message that receives is transmitted to corresponding STA.
Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims (11)

1, a kind of changing method of wireless site is characterized in that, comprises step:
A, wireless site STA send handoff request message to Target Wireless access point TAP;
B, described TAP wait for the arrival of news to the switching of STA feedback;
Channel and CAP that C, described STA return current wireless access point CAP communicate; And
D, the handoff request acknowledgment message that reception is come by the CAP feedback by described TAP on described CAP channel;
E1, be the handoff request success message in the handoff request acknowledgment message that receives, and the handoff request process is when finishing, channel and TAP that described STA is transferred to TAP communicate, the handoff procedure of end from described CAP to TAP.
2, the method for claim 1, it is characterized in that, STA is communicating in the process with described CAP in the described steps A, when being measured to described TAP signal strength signal intensity and being satisfied with switching condition with respect to the CAP signal strength signal intensity, is transferred to the TAP channel and sends handoff request message to TAP.
3, the method for claim 1 is characterized in that, also comprises step between described steps A and the B:
When A-1, described TAP receive the handoff request message that STA sends, judge whether in time to handle this handoff request message, if, execution in step A-2; Otherwise execution in step B;
A-2, described TAP are to the corresponding handoff request acknowledgment message of described STA feedback;
A-3, described STA judge whether the handoff request process finishes, if, on the channel of described TAP, communicate with TAP, finish handoff procedure from described CAP to TAP; Otherwise
A-4, return the described STA of steps A and continue to send follow-up handoff request message to TAP.
4, the method for claim 1 is characterized in that, STA receives on the CAP channel by TAP and specifically comprises by the process of the next handoff request acknowledgment message of CAP feedback among the described step D:
When D1, described TAP handle the handoff request message that STA sends, generate corresponding handoff request acknowledgment message, and be that described handoff request acknowledgment message encapsulates the address of CAP and the address of STA;
D2, the described TAP handoff request acknowledgment message after with encapsulation process sends to distributed system;
D3, described distributed system are forwarded to described CAP according to the CAP address of carrying in the handoff request acknowledgment message that receives with described handoff request acknowledgment message;
D4, described CAP are transmitted to STA according to the STA address of carrying in the handoff request acknowledgment message that receives with described handoff request acknowledgment message.
5, the method for claim 1 is characterized in that, also comprises before the described step e 1:
Described STA preestablishes the expected time length value of the described TAP feedback of expectation handoff request acknowledgment message; And
Judge whether in the expected time length value that sets, to receive the handoff request acknowledgment message that TAP comes by the CAP feedback, if, execution in step E1; Otherwise,
STA thinks the failure of this handoff request, returns steps A and continues to send this handoff request message to TAP.
6, the method for claim 1 is characterized in that, also comprises after described step D:
E2, be the handoff request success message, and the handoff request process is returned the described STA of steps A and is continued to send follow-up handoff request message to TAP when not finishing in the handoff request acknowledgment message that receives.
7, method as claimed in claim 6 is characterized in that, also comprises before the described step e 2:
Described STA preestablishes the expected time length value of the described TAP feedback of expectation handoff request acknowledgment message; And
Judge whether in the expected time length value that sets, to receive the handoff request acknowledgment message that TAP comes by the CAP feedback, if, execution in step E2; Otherwise,
STA thinks the failure of this handoff request, returns steps A and continues to send this handoff request message to TAP.
8, the method for claim 1 is characterized in that, also comprises after described step D:
E3, when the handoff request acknowledgment message that receives is the handoff request failed message, return the described STA of steps A and continue to send this handoff request message to TAP.
9, method as claimed in claim 8 is characterized in that, also comprises before the described step e 3:
Described STA preestablishes the expected time length value of the described TAP feedback of expectation handoff request acknowledgment message; And
Judge whether in the expected time length value that sets, to receive the handoff request acknowledgment message that TAP comes by the CAP feedback, if, execution in step E3; Otherwise,
STA thinks the failure of this handoff request, returns steps A and continues to send this handoff request message to TAP.
As the described method of 1~9 arbitrary claim, it is characterized in that 10, described STA is authentication request message and reassociation requests message to the handoff request message that TAP sends successively;
Described TAP waits for the arrival of news to the switching of STA feedback, and authentication request for the authentication request message of the described transmission of correspondence waits for the arrival of news and the reassociation requests of the reassociation requests message of corresponding described transmission waits for the arrival of news;
Described TAP is the reassociation requests response message of the reassociation requests message of the authentication request response message of authentication request message of corresponding described transmission and corresponding described transmission to the handoff request acknowledgment message that is in the STA feedback on the CAP channel by CAP.
11, a kind of WAP (wireless access point) is characterized in that, comprising:
The unit is known in the address, is used for the handoff request message sent according to wireless site STA, knows the address information of the current wireless access point CAP at the address information of described STA and this STA place;
The response message generation unit is used for after the handoff request message that described STA is sent is handled, and generates corresponding handoff request acknowledgment message;
The address encapsulation unit is used for knowing the address information that the unit gets access to according to described address, encapsulates the CAP address at this STA address and this STA place for the handoff request acknowledgment message of described response message generation unit generation;
The response message transmitting element, be used for the handoff request acknowledgment message after the encapsulation unit encapsulation process of described address is sent to distributed system, so that distributed system is forwarded to CAP according to the CAP address in the handoff request acknowledgment message with handoff request acknowledgment message, and make CAP handoff request acknowledgment message is transmitted to STA according to the STA address in the handoff request acknowledgment message.
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