CN108495347A - A kind of method of seamless roam - Google Patents
A kind of method of seamless roam Download PDFInfo
- Publication number
- CN108495347A CN108495347A CN201810178538.XA CN201810178538A CN108495347A CN 108495347 A CN108495347 A CN 108495347A CN 201810178538 A CN201810178538 A CN 201810178538A CN 108495347 A CN108495347 A CN 108495347A
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- client
- rssi
- identical networking
- controllers
- assoc
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/08—Reselecting an access point
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/16—Discovering, processing access restriction or access information
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/20—Selecting an access point
Abstract
The invention discloses a kind of methods of seamless roam, including step in detail below：A, identical networking, the access of b, identical networking are configured, c, identical networking exit, d, abnormality processing, and e, identical networking provide roaming user data service.By among the above, the method of seamless roam provided by the invention, handover delay is further decreased so that STA even switchings of the perception less than AP, meets those applications very harsh to handover delay requirement, such as the VoIP during radio roaming or real-time video transmission business.
Description
Technical field
The present invention relates to the field of wireless communication technique more particularly to a kind of methods of seamless roam.
Background technology
It is widely deployed in market currently based on the wireless aps product of 802.11 standards, office building, airport, the ground such as railway station,
Provide easily wireless access Internet service to the user.But for the real-time audio and video transmission application in roam procedure, commonly
AP products just seem unable to do what one wishes.The limited coverage area of general AP, client（STA）It often will be from one in roam procedure
A AP is switched to another AP.Most of client needs to disconnect the wireless connection with current service AP in handoff procedure,
Then the signal strength of scanning neighboring AP, in the best AP wireless associations of last selection signal intensity.This process causes wirelessly
Access service, which disconnects, continues milliseconds up to a hundred the even several seconds time, can not meet the requirement of real-time audio and video transmission application.
802.11r standards define a kind of fast handoff mechanisms of WLAN, and key management and resource allocation are wirelessly being weighed
It is realized before association or during re-association, reduces the time delay that switching is brought, reduce wireless access caused by handoff procedure
Influence of the service disruption to real time business.But still there is 50 milliseconds or so of handover delay in the equipment based on 802.11r standards,
This business such as VoIP high to certain delay requirements is still not applicable.
Therefore a kind of new wireless roaming method is needed to further decrease handover delay.
Invention content
The invention mainly solves the technical problem of providing a kind of method of seamless roam, further decrease handover delay with
So that STA even perceives the switching less than AP, those applications very harsh to handover delay requirement are met, such as wireless unrestrained
VoIP during trip or real-time video transmission business.
In order to solve the above technical problems, one aspect of the present invention is：Provide a kind of side of seamless roam
Method, including step in detail below：
A, identical networking, including multiple AP and the AC wireless controllers and client that are connect with AP are configured, wherein all AP
Same channel, SSID, BSSID, cipher mode and channel width are used, also sets up that there are one in CC on AC wireless controllers
Entreat controller；
B, the access of identical networking, client is scanned in identical networking to a SSID, and after the completion of scanning, client will be sent
AUTH frames and AP are authenticated, and then ASSOC processes are initiated by client after the completion of certification, due to being needed to visitor during ASSOC
Family end distributes a whole network unique ASSOC ID, and ASSOC ID can only be distributed by CC central controllers, CC central controllers
Select optimal AP and client associate, the CC central controllers after being successfully associated and between client cipher key interaction also by this most
Excellent AP is forwarded；
C, identical networking exits, and is exiting process, if it is normally exiting, client will issue current service APs mono-
A Disassociation Request management frames, current service APs are receiving Disassociation Request management
Disassociation Response management frames are replied after frame and notify the MAC Address of CC central controller clients；If it is
Exception exits, and current service APs will start after not receiving client for a long time to the ack responses of its keepalive frame
The WLAN kickoff flows that wirelessly driving carries, while the MAC of current service APs notice CC central controller clients
Location can delete the relevant information of this client to CC central controllers immediately；
D, abnormality processing, offline, the centers CC control that CC central controllers by the time-out of Echo Request messages detect AP
Device deletes this AP, and all clients associated under AP are switched to the RSSI in AP, the RSSI data structures of client
Maximum neighbouring AP will be as the new demand servicing AP of client；
E, identical networking provides roaming user data service, and the CC central controller moment pays close attention to the service APs of client and neighbouring
The variation of the client signal RSSI that APn is reported up, once the change triggers of RSSI switching flow, then CC central controllers
Client is switched to new demand servicing AP.
In a preferred embodiment of the present invention, the client also uses channel same as the AP being connected.
In a preferred embodiment of the present invention, for all AP in the same LAN, all AP are unified
It is configured and is managed by AC wireless controllers.
The beneficial effects of the invention are as follows：The method of the seamless roam of the present invention, further decreases handover delay so that STA
Even switching of the perception less than AP, meets those applications very harsh to handover delay requirement, such as radio roaming process
In VoIP or real-time video transmission business.
Description of the drawings
To describe the technical solutions in the embodiments of the present invention more clearly, make required in being described below to embodiment
Attached drawing is briefly described, it should be apparent that, drawings in the following description are only some embodiments of the invention, for
For those of ordinary skill in the art, without creative efforts, it can also be obtained according to these attached drawings other
Attached drawing, wherein：
Fig. 1 be seamless roam of the present invention method in AP switch flow chart.
Specific implementation mode
The technical scheme in the embodiments of the invention will be clearly and completely described below, it is clear that described implementation
Example is only a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, this field is common
All other embodiment that technical staff is obtained without making creative work belongs to the model that the present invention protects
It encloses.
The embodiment of the present invention includes：
A kind of method of seamless roam, including step in detail below：
A, identical networking, including multiple AP and the AC wireless controllers and client that are connect with AP are configured, wherein all AP
Same channel, SSID, BSSID, cipher mode and channel width are used, also sets up that there are one in CC on AC wireless controllers
Entreat controller；
B, the access of identical networking, client is scanned in identical networking to a SSID, and after the completion of scanning, client will be sent
AUTH frames and AP are authenticated, and then ASSOC processes are initiated by client after the completion of certification, due to being needed to visitor during ASSOC
Family end distributes a whole network unique ASSOC ID, and ASSOC ID can only be distributed by CC central controllers, CC central controllers
Select optimal AP and client associate, the CC central controllers after being successfully associated and between client cipher key interaction also by this most
Excellent AP is forwarded；
C, identical networking exits, and is exiting process, if it is normally exiting, client will issue current service APs mono-
A Disassociation Request management frames, current service APs are receiving Disassociation Request management
Disassociation Response management frames are replied after frame and notify the MAC Address of CC central controller clients；If it is
Exception exits, and current service APs will start after not receiving client for a long time to the ack responses of its keepalive frame
The WLAN kickoff flows that wirelessly driving carries, while the MAC of current service APs notice CC central controller clients
Location can delete the relevant information of this client to CC central controllers immediately；
D, abnormality processing, offline, the centers CC control that CC central controllers by the time-out of Echo Request messages detect AP
Device deletes this AP, and all clients associated under AP are switched to the RSSI in AP, the RSSI data structures of client
Maximum neighbouring AP will be as the new demand servicing AP of client；
E, identical networking provides roaming user data service, and the CC central controller moment pays close attention to the service APs of client and neighbouring
The variation of the client signal RSSI that APn is reported up, once the change triggers of RSSI switching flow, then CC central controllers
Client is switched to new demand servicing AP.
Invention describes a kind of special AP identical networking schemes.This special identical networking makes multiple AP works
Make to get up as the same AP, such client would not when being freely switched to another AP from an AP when moving
It is disconnected, does not have any switch or communicating interrupt.This special identical networking is zero switching（Zero Handoff, referred to as
ZHO）Identical networking.ZHO identical networkings need all AP all to use same channel and SSID.In addition all AP connections
Wireless client also use same channel.The identical networking network architecture is as shown in Figure 1.Wherein all AP are same
It is unified to be configured by AC wireless controllers in LAN, it manages.It is different with traditional AC, the AC of identical networking
It not only needs all AP to be configured to identical BSSID, SSID, frequency, cipher mode and channel width, and needs to be every
One client determines the most suitable provided wirelessly access of physics AP from the viewpoint of client, and only there are one empty
Quasi- AP provides it with wirelessly access.
The present invention will focus on the architecture design and handoff algorithms of identical networking.For between traditional AC and AP configuration and
Management function, the present invention will not be described in great detail.
There are 3 basic processes in WLAN wireless networks for terminal：Access, user data services and is exited.Assuming that M AP
Common-frequency network is formed, AC is APx（X=1~M）It is configured to identical channel ch, identical SSID and BSSID and identical
Cipher mode and channel width.In this way for client, only wirelessly access is provided it with there are one virtual AP.
Should also there be a central controller on AC（Central Controller, abbreviation CC）It is responsible for executing handoff algorithms and matches
AP is closed to complete the access of client and exit flow.
1, wireless access process
In access procedure, client will only be scanned to a SSID in this common-frequency network.After the completion of scanning, client will be sent out
It send AUTH frames and AP to be authenticated, ASSOC processes is then initiated by client after the completion of certification.Due to need during ASSOC to
Client distributes the unique ASSOC ID of a whole network, so ASSOC ID cannot be distributed by each physics APx, can only by CC Lai
Distribution.Each physics APx does not distribute ASSOC ID immediately after receiving Association Request management frames.But
Association Request management frames and corresponding RSSI are transmitted to CC.Wirelessly driving requires client to exist to WLAN
It sends out after Association Request management frames in certain time, such as 30ms, receives Association Response,
Otherwise client will retransmit Association Request management frames.Then suggest with a small amount of time, such as 10ms, going to receive in the sides CC
Collect Association Request management frames.After CC distributes ASSOC ID, the maximum APx of RSSI are selected, only APx are allowed to go
Associated client end, while APx only being allowed to remove to send the Association Response management frames for carrying ASSOC id informations to visitor
Family end.CC communicates also only thus APx completions with the EAPOL 4-Way Handshakes of client below.The key information for including in EAPOL is all
It is to be generated by the Hostapd modules on CC, APx is responsible for forwarding.In above-mentioned access procedure, CC determines client
Service APx.After access procedure successfully completes, service APx is determined, neighbouring APn is also determined therewith, can just be sent out after this
Raw AP switchings.Before this or access is unsuccessful, and since service APx is not determined, AP switchings will not occur.CC can be gone always
The service APx of client is selected until access procedure successfully completes.
2, it exits and abnormality processing
Process is being exited, if it is normally exiting, client will issue current service APs（In APs and above-mentioned access procedure
APx can be the same physics AP, can also be different）Disassociation Request management frames.APs is being received
Disassociation Response management frames are replied after Disassociation Request management frames and the centers CC is notified to control
The MAC Address of device client processed.Therefore CC and current service APs can delete the relevant information of this client.If it is
Exception exits（Such as client power-off）, current service APs do not receiving client to its keepalive frame for a long time
The WLAN wirelessly included kickoff flows of driving will be started after ack responses.The MAC Address of APs notices CC clients simultaneously.Together
Normal to exit equally, CC can delete the relevant information of this client with current service APs.
If AP abnormal restartings or power-off, it is offline that CC by the time-out of Echo Request messages detects AP.CC is deleted
This AP, and all clients associated under AP are switched to neighbouring AP by the switching flow of Fig. 1.Client RSSI data structures
The maximum neighbouring AP of middle RSSI will be as the new demand servicing AP of client.If client, such as iphone has the keep-alive work(of oneself
Can, it can detect AP exceptions itself and re-initiate association process, in this case according to wireless access flow processing.
3, user data services
In user data services process, client is always in roaming.Although physics AP in its imperceptible identical networking
Variation, central controller CC want moment concern service APs and the change adjacent to the APn reception client signal RSSI reported up
Change.May be neighbouring APn again for other clients additionally, due to service APs, so the physics AP in identical networking is not
Data access service to be only provided, and also provides the monitoring service of similar wireless probe.Wireless drive software is collected with frequency
They are reported to CC by all client mac address information that can be detected and RSSI under work.Since RSSI is by transmission rate
It is very big with the influence of bandwidth, therefore the RSSI reported should report the RSSI of management frame and control frame as far as possible.These 802.11
Frame is sent with fixed rate and fixed bandwidth, is comparable.If that report is the RSSI of data frame, this RSSI is wanted
In addition back-off caused by transmission rate and transmission bandwidth.CC receives the client address information and RSSI that physics AP is reported
Afterwards, receiving time should be stabbed to TSr and smooth filtered RSSI is stored in following data structure.Smothing filtering coefficient and work as
It is preceding to receive this AP to last CC and report the time tolerance of this client-side information related.Difference is bigger, and current RSSI is smooth
Shared weight is bigger in the process, i.e. RSSI=aRSSIcur+ (1-a) RSSIpre (0<a<1, a for current RSSI smoothed
Weight in journey).For neighbouring AP, if the RSSI that it is reported is more than the RSSI+RSSIh of service APs after smooth
（RSSIh is RSSI amount of hysteresis, and positive number prevents switching ping-pong）, CC also needs to record current time stamp T Sg, and otherwise TSg is set
It is set to 0.
STA RSSI data structure tables：
| STA MAC | The addresses service APs/ RSSI/TSr | The neighbouring addresses AP1/ RSSI/TSr/TSg | The neighbouring addresses AP2/ RSSI/TSr/TSg | … … | The neighbouring addresses APn/ RSSI/TSr/TSg |
Although there is no limit above-mentioned data structure will not be infinitely great for the number of physics AP under identical networking.Because for STA
For, the number of neighbouring AP will not be very much.Farther AP does not just receive the signal of STA.We can limit the maximum value of n
It is 32.When having more than the neighbouring AP of n and reporting STA RSSI information, that oldest information reported adjacent to AP will be by new
Information is covered.After each data structure update, CC will be operated as shown in Figure 1.Similar with RSSIh, TSh is that the time is slow
Stagnant amount is positive value, for eliminating unnecessary switching caused by RSSI mutation.
Central controller CC determines that client needs to be switched to next AP, it sends switching to new service AP first and asks
Seek message.Include the MAC Address and encryption information of client inside switching request message.New service AP first closes this client
Connection, is then arranged encryption information, finally sends switching response message to CC.CC is after receiving switching response message to old service
Association request message is gone in AP transmissions.Remove the MAC Address for including client inside association request message.Old service AP is first by this visitor
Family end is gone to be associated with, and then sends and goes associate response message to CC.CC reinitializes client after receiving associate response message
Hold RSSI data structures.
In conclusion the method for the seamless roam of the present invention, further decreases handover delay so that STA is even perceived not
To the switching of AP, meet those applications very harsh to handover delay requirement, for example, VoIP during radio roaming or
Real-time video transmission business.
Example the above is only the implementation of the present invention is not intended to limit the scope of the invention, every to utilize this hair
Equivalent structure or equivalent flow shift made by bright description is applied directly or indirectly in other relevant technology necks
Domain is included within the scope of the present invention.
Claims (3)
1. a kind of method of seamless roam, which is characterized in that including step in detail below：
A, identical networking, including multiple AP and the AC wireless controllers and client that are connect with AP are configured, wherein all AP
Same channel, SSID, BSSID, cipher mode and channel width are used, also sets up that there are one in CC on AC wireless controllers
Entreat controller；
B, the access of identical networking, client is scanned in identical networking to a SSID, and after the completion of scanning, client will be sent
AUTH frames and AP are authenticated, and then ASSOC processes are initiated by client after the completion of certification, due to being needed to visitor during ASSOC
Family end distributes a whole network unique ASSOC ID, and ASSOC ID can only be distributed by CC central controllers, CC central controllers
Select optimal AP and client associate, the CC central controllers after being successfully associated and between client cipher key interaction also by this most
Excellent AP is forwarded；
C, identical networking exits, and is exiting process, if it is normally exiting, client will issue current service APs mono-
A Disassociation Request management frames, current service APs are receiving Disassociation Request management
Disassociation Response management frames are replied after frame and notify the MAC Address of CC central controller clients；If it is
Exception exits, and current service APs will start after not receiving client for a long time to the ack responses of its keepalive frame
The WLAN kickoff flows that wirelessly driving carries, while the MAC of current service APs notice CC central controller clients
Location can delete the relevant information of this client to CC central controllers immediately；
D, abnormality processing, offline, the centers CC control that CC central controllers by the time-out of Echo Request messages detect AP
Device deletes this AP, and all clients associated under AP are switched to the RSSI in AP, the RSSI data structures of client
Maximum neighbouring AP will be as the new demand servicing AP of client；
E, identical networking provides roaming user data service, and the CC central controller moment pays close attention to the service APs of client and neighbouring
The variation of the client signal RSSI that APn is reported up, once the change triggers of RSSI switching flow, then CC central controllers
Client is switched to new demand servicing AP.
2. the method for seamless roam according to claim 1, which is characterized in that the client also uses and is connected
The same channels of AP.
3. the method for seamless roam according to claim 2, which is characterized in that all AP are in the same local
In net, all AP are unified to be configured and is managed by AC wireless controllers.
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| CN201810178538.XA CN108495347B (en) | 2018-03-05 | 2018-03-05 | Seamless roaming method |
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| CN201810178538.XA CN108495347B (en) | 2018-03-05 | 2018-03-05 | Seamless roaming method |
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