CN102752823A - Method for switching user terminal between access joints in WLAN (Wireless Local Area Network) based on AP (Access Point) collaboration - Google Patents
Method for switching user terminal between access joints in WLAN (Wireless Local Area Network) based on AP (Access Point) collaboration Download PDFInfo
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- CN102752823A CN102752823A CN2012102297634A CN201210229763A CN102752823A CN 102752823 A CN102752823 A CN 102752823A CN 2012102297634 A CN2012102297634 A CN 2012102297634A CN 201210229763 A CN201210229763 A CN 201210229763A CN 102752823 A CN102752823 A CN 102752823A
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Abstract
The invention provides a method for switching a user terminal between access joints in a WLAN (Wireless Local Area Network) based on AP (Access Point) collaboration. The switching method is mainly used for solving the problems in the prior art that the switching delay is overlong, and the switching mode is single. The method is technically characterized in that two selecting modes including a driving switching mode and a driven switching mode are adopted, wherein the driving switching mode is used for carrying out the switching from a network side; under a condition that a current AP is overloaded, the driving switch can be started for the AP, and an STA (Single Threaded Apartment) of the user terminal is selected from an STA set of the currently-connected user terminal and then is switched into an adjacent AP; if the communication quality of the STA of the user terminal is degraded, the driven switching mode can be automatically started through the STA of the user terminal, and the STA is switched into an optimal AP; and under the driving switching mode and the driven switching mode, channels to be scanned are subjected to priority ranking, and the time for scanning each channel is dynamically adjusted. The switching method has the advantages of less switching delay and high success rate in scanning and can be applied to distribution type wireless local networks with basic network support.
Description
Technical field
The invention belongs to communication technical field, the method that particularly user terminal switches between access point in the WLAN can be used for the optimization of wireless lan network side and user side communication quality.
Background technology
In recent years, wireless local area network technology has obtained development and successful application rapidly, and popularity improves constantly.WLAN WLAN provides fast, efficiently and WLAN access service cheaply for people.Insert Internet through wlan network and can various services be provided, such as VoIP, multimedia and transfer of data or the like for the user.For these application and service, continual and steady network insertion becomes inevitable requirement.User terminal STA that is to say through access point AP access network in WLAN, and STA must pass through through AP ability access network and other STA.Because the covering power of wlan network access point AP is limited,, can arranges many AP and make things convenient for the access of STA in order to enlarge the coverage of WLAN.As STA owing to move away from the current AP that connects; Perhaps too big or the like these reasons of the too many traffic of STA that current AP connects; When causing the communication quality of STA to drop to a certain degree; STA other AP around can seeking insert to keep the excellent communications quality, the handoff technique among Here it is the WLAN.Handoff technique briefly is exactly that STA passes through series of steps, and disconnection is connected with current AP's, selects the AP an of the best to be attached thereto communication, can suspend current communication in the STA handoff procedure, can continue original communication after the switching completion.
Handoff procedure logically can be divided into three phases: scanning discovery stage, authentication phase, association phase again, wherein:
First step sweep phase
The effect of sweep phase is exactly that STA seeks which to have around own can be for the AP of service is provided oneself, and knows this AP and own quality of connection, then from these AP the AP of the best of selection as switching target.Scan mode has drive sweep and active scan dual mode.802.11 agreement regulation AP broadcasts the beacon frame with self information by the periodicity of 100ms on the channel of itself working, drive sweep is to know the own RSSI of AP on every side through the passive AP of acceptance beacon frame of STA.STA need wait on scanning channel that the regular hour is to guarantee to receive the beacon frame of AP when carrying out drive sweep.Number of available channels at China 802.11b/g is 11, and 802.11a is 13.If STA scans each channel, and on each channel, stop 100ms, then scanning delay will reach 1100ms, can't satisfy the requirement of real time business at all.Active scan is initiatively initiated by STA, and STA sends the Probe Request frame of inquiring after successively on each channel, and AP receives Probe Request frame and then replys Probe Response.STA is known the RSSI of AP on every side through the Probe Response frame that the AP that receives on this channel returns.In active scan, two values have been defined: minimum channel time and maximum channel time.If STA receives the Probe Response frame that AP sends at minimum channel in the time, then STA continues on this channel, to wait for up to the maximum channel time, to guarantee to receive the response of AP all on this channel.If STA does not receive the response of any AP at minimum channel in the time, there is not AP to be operated on this channel around then thinking, STA carries out the scanning of next channel immediately.
The second step authentication phase
After STA successfully finds some new AP, and when therefrom selecting an optimum AP to communicate, must could communicate with this AP through the authentication of AP, could access network.No matter be which kind of authentication mode, necessary step is that STA sends authentication request information to AP, and to the response of website transmission authentication success or failure, authentication mode is safe more after the authentication of AP process, and time delay is big more.
The 3rd re-associates stage in step
After accomplishing top two steps, STA sends the claim frame of re-associates to new connection AP, and AP sends it back the response frame of re-associates to website.STA has accomplished association process with new AP like this, and STA just can carry out the transmission of data between network.The time delay of re-associates process is the exchange process of re-associates frame, after website is received the message of success identity, sends the request message of re-associates to AP, has just accomplished switching after receiving the re-associates respective frame of AP.
A lot of problems can occur in the handoff procedure, wherein handover delay is of paramount importance with finding best AP.Handover delay is crossed the communication quality that senior general has influence on the real-time service such as VoIP significantly.Handover delay mainly is made up of the time delay of above three phases: scanning delay, the authentication time delay with reconnect time delay.Through a large amount of research, scanning delay has accounted for more than 90% of handover delay, and the authentication time delay is with to reconnect time delay shorter, so scanning process also is the emphasis of optimizing in the handoff procedure.Might not cause repeatedly switching if the AP that switches to is not best AP, cause the decline of user terminal communication quality easily yet.
To the problem that occurs in the user terminal handoff procedure among the WLAN, a lot of relevant separating have appearred in recent years
The way of determining, but these methods all exist certain deficiency.Such as Tuning algorithm based on adjustment minimum channel time and maximum channel time; This method is especially little with these two value settings; This has obtained effect on the minimizing handover delay; But cause scanning failure easily, just possibly have AP on the channel but since minimum channel time and maximum channel time be provided with too small, the time that STA treats on channel is weak point and cause accepting the response of AP too.This algorithm only is to consider from STA end simultaneously, just only switches and triggers from STA, and do not consider the factor of network side, causes the terminal to switch to non-best AP easily and duplicates the problem of switching.
Summary of the invention
The objective of the invention is to deficiency to above-mentioned prior art; Propose a kind of based on the changing method of user terminal between access point among the WLAN of AP cooperation; To reduce handover delay; Improve user terminal communication continuity in handoff procedure, and guarantee that STA switches to best AP, avoid repeating switching.
For realizing above-mentioned purpose, technical scheme of the present invention comprises the steps:
(1) current access point AP
aWith neighboring access point AP
bRegularly carry out information exchange, make current access point AP
aObtain neighboring access point AP
bInformation, this information comprises neighboring access point AP
bWorking channel number and load;
(2) current access point AP
aWith the neighboring access point AP that obtains
bInformation, the mode through beacon frame is handed down to and current access point AP
aThe user terminal STA that connects;
(3) user terminal STA receives current access point AP
aThe neighboring access point AP that issues
bInformation after, check current acknowledge(ment) signal intensity RSSI, if current RSSI is less than the passive handoff threshold T that sets
a=75dB, then execution in step (4) starts passive switching, otherwise execution in step (5);
(4) user terminal STA is to current access point AP
aSend passive handoff request, begin passive switching;
4a) user terminal STA utilizes current access point AP
aThe information that issues is confirmed the scanning set, is about to appear at the neighboring access point AP in the information
bConfirm as the scanning set;
4b) user terminal STA calculates own respectively and scans each neighboring access point AP in the set
bDistance, confirm priority according to distance, the nearlyer priority of distance is high more;
4c) user terminal STA selective channel in the scanning set is 1,6,11 these three channels if in the scanning set channel number is arranged, and then preferentially selects this three channels, otherwise, select priority the highest and not by scanned channel;
4d) user terminal STA switches to the channel of selection, and on scanning channel, sends probe request Probe Request, and the initial value of minimum channel time MinT and maximum channel time MaxT is respectively 10ms and 20ms;
4e) user terminal STA is according to whether receiving that in minimum channel time MinT probing response frame Probe Response confirms execution in step; If user terminal STA receives probing response frame Probe Response in minimum channel time MinT; Execution in step (4f) then; Otherwise, execution in step (4g);
4f) user terminal STA selects next channel after stopping maximum channel time MaxT on the scanning channel, and reduces each 5ms of value of minimum channel time MinT and maximum channel time MaxT, and repeating step (4c) is to (4e), up to having scanned all channels;
4g) user terminal STA selects next channel after stopping minimum channel time MinT on the scanning channel, and increases each 5ms of value of minimum channel time MinT and maximum channel time MaxT, and repeating step (4c) is to (4e), up to having scanned all channels;
4h) user terminal STA is according to acknowledge(ment) signal intensity RSSI, and from scanning result, selecting acknowledge(ment) signal intensity RSSI the maximum is that best access point AP switches, and accomplishes passive switching;
(5) current access point AP
aCheck whether self overloads, and check the passive handoff request of whether receiving that user terminal STA sends, if current access point AP
aOverload and do not receive the passive handoff request that user terminal STA sends, then current access point AP
aStart initiatively and switch, execution in step (6), otherwise, current access point AP
aOneself state is checked in circulation;
(6) current access point AP
aStart initiatively and switch, and to current access point AP
aThe user terminal STA that connects issues initiatively switch frame.
Described active is switched, and carries out as follows:
6a) receive that initiatively the user terminal STA of switch frame checks that whether current acknowledge(ment) signal intensity RSSI is less than active handoff threshold T
b=80dB is if the acknowledge(ment) signal intensity RSSI of user terminal STA is less than active handoff threshold T
b, execution in step (6b) then, otherwise, user terminal STA proper communication;
6b) all neighboring access point AP of user terminal STA dynamic scan
b, and with acknowledge(ment) signal intensity RSSI greater than active handoff threshold T
bScanning result writing scan as a result in the table, behind the user terminal STA end of scan this scanning result table is fed back to current access point AP
a
6c) current access point AP
aUtilize the scanning result of each user terminal STA feedback, signal calculated intensity load value: RL
Ij=RSSI
Ij* f
i(l)
F wherein
i(l)=exp (k
1* l)+k
2The expression intermediate variable, l is candidate's access point AP
iLoad, k
1Be the weight that balance factor several 1 is used for adjusting load l, k
2Be that balance factor several 2 is used for adjusting acknowledge(ment) signal intensity RSSI
IjWeight, acknowledge(ment) signal intensity RSSI
IjBe candidate's access point AP
iWith the candidate user terminal STA
jBetween signal quality quality metric;
6d) current access point AP
aWith signal strength signal intensity load value RL
IjDescending ordering forms signal strength signal intensity load tabulation RL;
6e) current access point AP
aFrom signal strength signal intensity load tabulation RL, select to come the foremost, and the candidate's access point AP that was not selected
iWith the candidate user terminal STA
j, and to candidate's access point AP
iSend handoff request and candidate user terminal STA
jLoad information, candidate's access point AP
iReceive current access point AP
aHandoff request of sending and candidate user terminal STA
jLoad information after can check that present load adds the candidate user terminal STA
jLoad whether overload, if do not overload candidate's access point AP
iTo current access point AP
aFeedback is switched affirmation;
6f) current access point AP
aCheck and whether receive candidate's access point AP
iThe switching affirmation of sending, if receive then execution in step (6g), otherwise execution in step (6e);
6g) current access point AP
aTo the candidate user terminal STA
jSend the handover information frame;
6h) candidate user terminal STA
jReceive current access point AP
aThe handover information frame after, switch to candidate's access point AP
i, accomplish initiatively and switch.
The present invention compared with prior art has following advantage:
1) changing method that active is switched and passive switching combines of the present invention's proposition has solved one-sided startup switching problem, the gain that had both improved network side, the gain that has improved user terminal STA side again.
2) the dynamic scan technology among the present invention is carried out dynamic change to minimum channel time and maximum channel time then through the channel that will scan is carried out prioritization, has both reduced handover delay, ensures being scanned into power again.
Description of drawings
Fig. 1 is a general flow chart of the present invention;
Fig. 2 is the passive switching sub-process figure among the present invention;
Fig. 3 initiatively switches sub-process figure among the present invention;
Fig. 4 is the dynamic scan sub-process figure among the present invention.
Embodiment
With reference to Fig. 1, performing step of the present invention is following:
Step 1: current access point AP
aWith neighboring access point AP
bRegularly carry out information exchange, make current access point AP
aObtain neighboring access point AP
bInformation, this information comprises neighboring access point AP
bWorking channel number and load, wherein load is the ratio of current throughput and channel width.
Step 2: current access point AP
aWith the neighboring access point AP that obtains
bInformation, the mode through beacon frame is handed down to and current access point AP
aThe user terminal STA that connects, the mode of described beacon frame is the beacon frame beacon that utilizes in 802.11 standards, in beacon frame beacon, increases neighboring access point AP
bInformation is again with neighboring access point AP
bInformation sends to user terminal STA with beacon frame beacon.
Step 3: user terminal STA receives current access point AP
aThe neighboring access point AP that issues
bInformation after, check current reception signal strength signal intensity RSSI, this reception signal strength signal intensity RSSI is the metric of signal quality between user terminal STA and the access point AP, if current reception signal strength signal intensity RSSI is less than passive handoff threshold T
a, then execution in step (4) starts passive switching, otherwise execution in step (5) starts initiatively switching.
Step 4: user terminal STA is to current access point AP
aSend passive handoff request, begin passive switching:
With reference to Fig. 2, the concrete realization of this step is following:
4a) user terminal STA utilizes current access point AP
aThe information that issues is confirmed the scanning set, is about to appear at the neighboring access point AP in the information
bChannel confirm as scanning set;
4b) channel in the scanning set is carried out dynamic scan
With reference to Fig. 4, being implemented as follows of dynamic scan:
4b1) user terminal STA calculates own respectively and scans each neighboring access point AP in the set
bDistance, confirm channel priority according to distance, the nearlyer priority of distance is high more;
4b2) user terminal STA selective channel in the scanning set is 1,6,11 these three channels if in the scanning set channel number is arranged, and then preferentially selects this three channels, otherwise, select priority the highest and not by scanned channel;
4b3) user terminal STA switches to the channel of selection, and on scanning channel, sends probe request Probe Request, the neighboring access point AP on the scanning channel
bCan feed back probing response frame Probe Response after receiving probe request Probe Request, the initial value of minimum channel time MinT and maximum channel time MaxT is respectively 10ms and 20ms;
4b4) user terminal STA is according to whether receiving that in minimum channel time MinT probing response frame Probe Response confirms execution in step; If user terminal STA receives probing response frame Probe Response in minimum channel time MinT; Then according to probing response frame Probe Response recorder signal strength signal intensity RSSI; And execution in step (4b5), otherwise, execution in step (4b6);
4b5) user terminal STA stops maximum channel time MaxT on scanning channel; In the time of staying, note each the probing response frame Probe Response that receives; The time of staying finishes the back and selects next channel; And each 5ms of value of minimizing minimum channel time MinT and maximum channel time MaxT; Repeating step (4b2) is to (4b4), up to having scanned all channels;
4b6) user terminal STA is after stopping minimum channel time MinT on the scanning channel; Select next channel; And each 5ms of value of increase minimum channel time MinT and maximum channel time MaxT, repeating step (4b2) is to (4b4), up to having scanned all channels;
4c) user terminal STA is according to acknowledge(ment) signal intensity RSSI, and from scanning result, selecting acknowledge(ment) signal intensity RSSI the maximum is that best access point AP switches, and accomplishes passive switching.
Step 5, current access point AP
aCheck whether self overloads, and check the passive handoff request of whether receiving that user terminal STA sends that overload here is meant current access point AP
aThroughput reach more than 55% of bandwidth, if current access point AP
aOverload and do not receive the passive handoff request that user terminal STA sends, then current access point AP
aStart initiatively and switch, execution in step (6), otherwise, current access point AP
aCirculation is checked oneself state and is upgraded neighboring access point AP
bInformation.
Step 6, current access point AP
aStart initiatively and switch, and to current access point AP
aThe user terminal STA that connects issues initiatively switch frame.
With reference to Fig. 3, the concrete realization of this step is following:
6a) receive that initiatively the user terminal STA of switch frame checks that whether current acknowledge(ment) signal intensity RSSI is less than active handoff threshold T
bIf the acknowledge(ment) signal intensity RSSI of user terminal STA is less than active handoff threshold T
b, then user terminal STA utilizes current access point AP
aThe information that issues is confirmed scanning set and execution in step (6b), otherwise, user terminal STA proper communication;
6b) user terminal STA carries out dynamic scan to the channel in the scanning set
With reference to Fig. 4, being implemented as follows of dynamic scan:
6b1) user terminal STA calculates own respectively and scans each neighboring access point AP in the set
bDistance, confirm channel priority according to distance, the nearlyer priority of distance is high more;
6b2) user terminal STA selective channel in the scanning set is 1,6,11 these three channels if in the scanning set channel number is arranged, and then preferentially selects this three channels, otherwise, select priority the highest and not by scanned channel;
6b3) user terminal STA switches to the channel of selection, and on scanning channel, sends probe request Probe Request, the neighboring access point AP on the scanning channel
bCan feed back probing response frame Probe Response after receiving probe request Probe Request, the initial value of minimum channel time MinT and maximum channel time MaxT is respectively 10ms and 20ms;
6b4) user terminal STA is according to whether receiving that in minimum channel time MinT probing response frame Probe Response confirms execution in step; If user terminal STA receives probing response frame Probe Response in minimum channel time MinT; Then according to probing response frame Probe Response recorder signal strength signal intensity RSSI; And execution in step (6b5), otherwise, execution in step (6b6);
6b5) user terminal STA stops maximum channel time MaxT on scanning channel; In the time of staying, note each the probing response frame Probe Response that receives; The time of staying finishes the back and selects next channel; And each 5ms of value of minimizing minimum channel time MinT and maximum channel time MaxT; Repeating step (6b2) is to (6b4), up to having scanned all channels;
6b6) user terminal STA is after stopping minimum channel time MinT on the scanning channel; Select next channel; And each 5ms of value of increase minimum channel time MinT and maximum channel time MaxT, repeating step (6b2) is to (6b4), up to having scanned all channels;
6c) user terminal STA has scanned all neighboring access point AP
bAfter, with acknowledge(ment) signal intensity RSSI greater than active handoff threshold T
bScanning result writing scan as a result in the table, user terminal STA feeds back to current access point AP with this scanning result table
a
6d) current access point AP
aUtilize the scanning result of each user terminal STA feedback, signal calculated intensity load value: RL
Ij=RSSI
Ij* f
i(l),
F wherein
i(l)=exp (k
1* l)+k
2The expression intermediate variable, l is candidate's access point AP
iLoad, k
1Be the weight that balance factor several 1 is used for adjusting load l, k
2Be that balance factor several 2 is used for adjusting acknowledge(ment) signal intensity RSSI
IjWeight, acknowledge(ment) signal intensity RSSI
IjBe candidate's access point AP
iWith the candidate user terminal STA
jBetween signal quality quality metric;
6e) current access point AP
aWith signal strength signal intensity load value RL
IjDescending ordering forms signal strength signal intensity load tabulation RL;
6f) current access point AP
aFrom signal strength signal intensity load tabulation RL, select to come the foremost, and the candidate's access point AP that was not selected
iWith the candidate user terminal STA
j, and to candidate's access point AP
iSend handoff request and candidate user terminal STA
jLoad information, candidate's access point AP
iReceive current access point AP
aHandoff request of sending and candidate user terminal STA
jLoad information after, if candidate's access point AP
iPresent load add the candidate user terminal STA
jLoad not overload then to current access point AP
aFeedback is switched affirmation;
6g) current access point AP
aCheck and whether receive candidate's access point AP
iThe switching affirmation of sending, if receive then execution in step (6f), otherwise execution in step (6h);
6h) current access point AP
aTo the candidate user terminal STA
jSend the handover information frame;
6i) candidate user terminal STA
jReceive current access point AP
aThe handover information frame after, switch to candidate's access point AP
i, accomplish initiatively and switch.
Terminological interpretation
WLAN:Wireless Local Area Network; WLAN;
AP:Access Point; Access point;
STA:Station; The user;
MinT:MinChannelTime: minimum channel time;
MaxT:MaxChannelTime: maximum channel time;
Probe Request: probe requests thereby;
Probe Response: probe response;
RSSI:Received Signal Strength Indication: acknowledge(ment) signal intensity indication.
Claims (3)
1. one kind based on the changing method of user terminal between access point among the WLAN of AP cooperation, comprises the steps:
(1) current access point AP
aWith neighboring access point AP
bRegularly carry out information exchange, make current access point AP
aObtain neighboring access point AP
bInformation, this information comprises neighboring access point AP
bWorking channel number and load;
(2) current access point AP
aWith the neighboring access point AP that obtains
bInformation, the mode through beacon frame is handed down to and current access point AP
aThe user terminal STA that connects;
(3) user terminal STA receives current access point AP
aThe neighboring access point AP that issues
bInformation after, check current acknowledge(ment) signal intensity RSSI, if current RSSI is less than the passive handoff threshold T that sets
a, then execution in step (4) starts passive switching, otherwise execution in step (5);
(4) user terminal STA is to current access point AP
aSend passive handoff request, begin passive switching;
4a) user terminal STA utilizes current access point AP
aThe information that issues is confirmed the scanning set, is about to appear at the neighboring access point AP in the information
bChannel confirm as scanning set;
4b) user terminal STA calculates own respectively and scans each neighboring access point AP in the set
bDistance, confirm channel priority according to distance, the nearlyer priority of distance is high more;
4c) user terminal STA selective channel in the scanning set is 1,6,11 these three channels if in the scanning set channel number is arranged, and then preferentially selects this three channels, otherwise, select priority the highest and not by scanned channel;
4d) user terminal STA switches to the channel of selection, and on scanning channel, sends probe request Probe Request, and the initial value of minimum channel time MinT and maximum channel time MaxT is respectively 10ms and 20ms;
4e) user terminal STA is according to whether receiving that in minimum channel time MinT probing response frame Probe Response confirms execution in step; If user terminal STA receives probing response frame Probe Response in minimum channel time MinT; Execution in step (4f) then; Otherwise, execution in step (4g);
4f) user terminal STA selects next channel after stopping maximum channel time MaxT on the scanning channel, and reduces each 5ms of value of minimum channel time MinT and maximum channel time MaxT, and repeating step (4c) is to (4e), up to having scanned all channels;
4g) user terminal STA selects next channel after stopping minimum channel time MinT on the scanning channel, and increases each 5ms of value of minimum channel time MinT and maximum channel time MaxT, and repeating step (4c) is to (4e), up to having scanned all channels;
4h) user terminal STA is according to acknowledge(ment) signal intensity RSSI, and from scanning result, selecting acknowledge(ment) signal intensity RSSI the maximum is that best access point AP switches, and accomplishes passive switching;
(5) current access point AP
aCheck whether self overloads, and check the passive handoff request of whether receiving that user terminal STA sends, if current access point AP
aOverload and do not receive the passive handoff request that user terminal STA sends, then current access point AP
aStart initiatively and switch, execution in step (6), otherwise, current access point AP
aOneself state is checked in circulation;
(6) current access point AP
aStart initiatively and switch, and to current access point AP
aThe user terminal STA that connects issues initiatively switch frame.
2. according to the described changing method of claim 1, wherein step (2) is described is meant with the beacon frame beacon in 802.11 standards through photos and sending messages under the beacon frame mode, in beacon frame beacon, increases neighboring access point AP
bInformation is again with neighboring access point AP
bInformation sends to user terminal STA with beacon frame beacon.
3. changing method according to claim 1, the active in the wherein said step (6) is switched, and comprises the steps:
6a) receive that initiatively the user terminal STA of switch frame checks that whether current acknowledge(ment) signal intensity RSSI is less than active handoff threshold T
bIf the acknowledge(ment) signal intensity RSSI of user terminal STA is less than active handoff threshold T
b, execution in step (6b) then, otherwise, user terminal STA proper communication;
6b) user terminal STA utilizes all neighboring access point AP of dynamic scan scanning
bAfter, and with acknowledge(ment) signal intensity RSSI greater than active handoff threshold T
bScanning result writing scan as a result in the table, user terminal STA feeds back to current access point AP with this scanning result table
a
6c) current access point AP
aUtilize the scanning result of each user terminal STA feedback, signal calculated intensity load value: RL
Ij=RSSI
Ij* f
i(l)
F wherein
i(l)=exp (k
1* l)+k
2The expression intermediate variable, l is candidate's access point AP
iLoad, k
1Be the weight that balance factor several 1 is used for adjusting load l, k
2Be that balance factor several 2 is used for adjusting acknowledge(ment) signal intensity RSSI
IjWeight, acknowledge(ment) signal intensity RSSI
IjBe candidate's access point AP
iWith the candidate user terminal STA
jBetween signal quality quality metric;
6d) current access point AP
aWith signal strength signal intensity load value RL
IjDescending ordering forms signal strength signal intensity load tabulation RL;
6e) current access point AP
aFrom signal strength signal intensity load tabulation RL, select to come the foremost, and the candidate's access point AP that was not selected
iWith the candidate user terminal STA
j, and to candidate's access point AP
iSend handoff request and candidate user terminal STA
jLoad information, candidate's access point AP
iReceive current access point AP
aHandoff request of sending and candidate user terminal STA
jLoad information after can check that present load adds the candidate user terminal STA
jLoad whether overload, if do not overload candidate's access point AP
iTo current access point AP
aFeedback is switched affirmation;
6f) current access point AP
aCheck and whether receive candidate's access point AP
iThe switching affirmation of sending, if receive then execution in step (6g), otherwise execution in step (6e);
6g) current access point AP
aTo the candidate user terminal STA
jSend the handover information frame;
6h) candidate user terminal STA
jReceive current access point AP
aThe handover information frame after, switch to candidate's access point AP
i, accomplish initiatively and switch.
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Cited By (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103167586A (en) * | 2013-03-01 | 2013-06-19 | 北京傲天动联技术股份有限公司 | Wireless terminal access and reselecting method based on access point (AP) cluster |
| CN104023357A (en) * | 2014-05-06 | 2014-09-03 | 京信通信系统（中国）有限公司 | Load balancing method of concentrated-type wireless local area network and access controller |
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| CN104885529A (en) * | 2012-12-25 | 2015-09-02 | Lg电子株式会社 | Improved scanning method and apparatus in wireless lan system |
| CN104885529B (en) * | 2012-12-25 | 2018-10-23 | Lg电子株式会社 | Improved scan method in Wireless LAN system and equipment |
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