EP4079013A1

EP4079013A1 - Improved switching between physical access points sharing the same virtual access point identifier

Info

Publication number: EP4079013A1
Application number: EP20845189.8A
Authority: EP
Inventors: Jean-Philippe Javaudin; Jean-Michel Bonnamy; José SALDANA; José RUIZ MAS; Julian FERNANDEZ NAVAJAS
Original assignee: Orange SA
Current assignee: Orange SA
Priority date: 2019-12-20
Filing date: 2020-12-14
Publication date: 2022-10-26
Also published as: FR3106950A1; US20230034345A1; WO2021123582A1; CN115053550A

Abstract

Improved switching between physical access points sharing the same virtual access point identifier. The invention relates to a method for managing the switching of a terminal (STA) between a plurality of physical access points (AP1, AP2) to a Wi-Fi network, a virtual access point identifier (LVAP) dedicated to the terminal being assigned by a controller (CTL) to a first physical access point (AP1), the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the method comprising at the first access point:  transmitting (1003), from the first physical access point to the controller, information relating to the capabilities of the terminal,  receiving (1010) an order to switch from the first connection to a second connection established between the terminal and a second physical access point (AP2) of the plurality using the same virtual access point identifier, the first and the second connections being adapted to the capabilities of the terminal.

Description

DESCRIPTION

Improved failover between physical access points sharing the same virtual access point ID

1. Field of the invention

The invention lies in the field of Wi-Fi networks, and more particularly that of a Wi-Fi network using a virtual access point (LVAP) managed by a network controller SDN (Sofware Defined Network, in English) .

2. State of the prior art

An advantage of a virtual access point is to allow the switching of a terminal (also called a station) between two physical access points (AP) Wi-Fi transparently for the terminal, simply by moving the device. Outgoing AP to the incoming AP the LVAP virtual access point identifier, with its characteristics, routing rules, and terminal attachment. However, the fact that the terminal does not need to re-associate with the new physical AP can cause problems. Indeed, the match between the capacities of the station and the capacities of the new physical AP can be broken if the different physical APs of the network do not have identical capacities.

This is the case for example when a Wi-Fi network consists of several heterogeneous Wi-Fi APs where some support Wi-Fi 4, and others Wi-Fi 5, or when the maximum bandwidth supported is 80 MHz for some APs and 160 MHz for others.

Figure 1 shows a simple example of a Wi-Fi network with 2 access points AP1 and AP2. The AP1 supports Wi-Fi 5 (IEEE 802.11ac radio standard), in the 5 GHz band with a maximum bandwidth of 80 MHz. The AP2 also supports Wi-Fi 5, in the 5 GHz band but with a maximum bandwidth of 160MHz (this functionality is optional in the IEEE 802.11ac standard).

A Wi-Fi station (STA), supporting Wi-Fi 5 with 160 MHz connects to this network. The following 2 cases can then occur.

If a Wi-Fi station (STA) associates with GAR1 first, the connection will be established with a bandwidth of 80 MHz. Then, as illustrated in FIG. 1, if the station approaches GAR2 while moving away from IΆR1, its Wi-Fi connection ends up switching from IΆR1 to IΆR2. During this transparent switchover for the station, the station will not try to re-associate and the connection will not go to 160 MHz, which would have been possible because of the respective functionalities of IΆR2 and of the STA station. The resulting quality enjoyed by the station is lower, but the connection will still work.

Conversely, if the STA first associates with IΆR2 then switches to IΆR1, the connection will be established with a bandwidth of 160 MHz. During this transparent switchover for the station, the station will not seek to re-associate and will continue to transmit with a bandwidth of 160 MHz. This feature is not supported by IΆR1, the connection will be broken, causing an interruption of service. The STA station will reset a new connection after a delay ranging from several hundred ms to several seconds.

The publication "Traffic Management in LTE-Wi-Fi Slicing Networks", by ASD Alfoudi et al., IEEE 2017, discloses that a physical access point periodically communicates the status of its connections to the controller. This allows the CTL controller to know if the signal strength of a station connected to this access point, received by this access point, goes below a certain threshold, in which case the quality of the communications carried by this access point. access to the station may be endangered. However, the controller can trigger a switch from the station to another physical access point, simply by moving the LVAP identifier, already known by the station, from the first to the second access point. However, this method does not prevent the aforementioned drawbacks from occurring.

One of the aims of the invention is to remedy these drawbacks of the state of the art.

3. Disclosure of the invention

The invention improves the situation using a method for managing the switchover of a terminal between a plurality of physical access points to a Wi-Fi network, a virtual access point identifier dedicated to the terminal. being assigned by a controller to a first physical access point, the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the method comprising at the first point access:

• transmit, from the first physical access point to the controller, information relating to the capabilities of the terminal,

• receive an order to switch from the first connection to a second connection established between the terminal and a second physical access point of the plurality using the same virtual access point identifier, the first and the second connection being adapted to the terminal capabilities.

The criterion determined for switching a terminal from the first access point to a second is for example an excessively low power level of the signal between the terminal and the first access point. This level is perceived by the access point which can for example communicate it periodically to the controller. In a virtual access point context, when the controller decides to switch the terminal to a second physical access point preferable to the first, the first access point has the virtual access point identifier removed by the controller, which assigns it to the second physical access point. Thus, the terminal continues to send its data frames with the same recipient identifier, and does not see that the physical access point has changed. Advantageously, by virtue of the proposed method, and unlike the prior art, the second connection is established taking into account the capacities particulars of the terminal. According to the prior art, information relating to the quality of the current connection can be transmitted to the controller, but no information specific to the single terminal itself is transmitted.

In the present documents, by "capacity" of a terminal or of an access point, is meant any property, functionality or software or physical configuration, present in the terminal or in the access point having an impact on the quality of its operation.

According to one aspect of the invention, the management method comprises extracting information relating to the capabilities of the terminal from a Probe Request type message sent by the terminal and received by the first physical access point.

During the association phase between the terminal and the physical access point, a Probe Request type message is sent by the terminal, in a known manner. This message includes the capabilities of the terminal that the physical access point needs to know in order to optimally adapt the connection established between the terminal and itself.

According to one aspect of the invention, the management method comprises extracting information relating to the capabilities of the terminal from an Association Request type message sent by the terminal and received by the first physical access point. During the association phase between the terminal and the physical access point, an Association Request type message is sent by the terminal, in a known manner. This message includes the capabilities of the terminal that the terminal has selected to best match those of the physical access point.

According to one aspect of the management method, information relating to the capabilities of the terminal is transmitted to the controller in a message requesting the creation of a virtual access point.

The reception of a Probe Request by the first access point triggers the transmission of a request, by the first access point to the controller, in order to obtain a virtual access point identifier dedicated to the terminal. Advantageously, it is in this request that the parameters relating to the capacities of the terminal are transmitted.

According to one aspect of the invention, the management method comprises reconfiguring the first connection, prior to switching if the capacities of the second physical access point are lower than those of the first.

Thanks to this aspect, for example, if the first connection, established according to the best common capacities between the terminal and the first physical access point, is established at 160 MHz, and the second physical access point does not go above 80 MHz, the second connection is not interrupted. Indeed, before the switchover, the first connection is modified to switch from the 160 MHz band to the 80 MHz band, which prevents the terminal, for which the switchover is transparent, from transmitting 160 MHz data frames to the second physical access point unable to receive them, which would inevitably interrupt the connection and force the terminal to restart the association procedure with a physical access point. In the present, by "lower capacity" or "higher capacity" is meant a resulting lower quality, respectively a resulting higher quality, of operation of the equipment under consideration.

According to one aspect of the invention, the management method comprises the reconfiguration of the second connection, following the switchover if the capacities of the second physical access point are greater than those of the first.

Thanks to this aspect, for example, if the first connection, established according to the best common capacities between the terminal and the first physical access point, is established at 80 MHz, and the second physical access point is capable of '' reach 160 MHz, the second connection is not blocked at 80 MHz. Indeed, after the switchover, the second connection is modified to switch from the 80 MHz band to the 160 MHz band, which increases the quality of the connection made possible by the capacities of the terminal. The invention also relates to a method of controlling the switching of a terminal between a plurality of physical access points to a Wi-Fi network, a virtual access point identifier dedicated to the terminal being assigned by a controller to a first one. physical access point, the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the method comprising at the level of the controller:

• receive, from the first physical access point, information relating to the capacities of the terminal,

• and, according to a determined criterion, triggering the switch from the first connection to a second connection established between the terminal and a second physical access point of the plurality using the same virtual access point, the first and the second connection being adapted to the capacities of the terminal.

According to one aspect of the control method, information relating to the capabilities of the terminal is transmitted to the controller in a virtual access point creation request message sent by the first physical access point.

According to one aspect of the invention, the control method comprises the transmission to the first physical access point of an order to reconfigure the first connection, prior to switching if the capacities of the second physical access point are lower. to those of the first.

According to one aspect of the invention, the control method comprises the transmission to the second physical access point of an order to reconfigure the second connection, following the switchover if the capacities of the second physical access point are greater. to those of the first.

Different aspects of the management and control methods which have just been described can be implemented independently of one another or in combination with one another. The invention also relates to a device for managing the switchover of a terminal between a plurality of physical access points to a Wi-Fi network, a virtual access point identifier dedicated to the terminal being assigned by a controller to a first one. physical access point, the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the device comprising a receiver, a transmitter, a processor and a memory coupled to the processor with instructions to be executed by the processor to:

This device, capable of implementing the failover management method which has just been described in all its embodiments, is intended to be implemented in a physical access point of a Wi-Fi network.

The invention also relates to a device for controlling the switching of a terminal between a plurality of physical access points to a Wi-Fi network, a virtual access point identifier dedicated to the terminal being assigned by a controller to a first one. physical access point, the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the device comprising a receiver, a transmitter, a processor and a memory coupled to the processor with instructions to be executed by the processor to:

• store said information in memory,

• and, according to a determined criterion, trigger the switch from the first connection to a second connection established between the terminal and a second physical access point of the plurality using the same virtual access point, the first and the second connection being adapted to the capabilities of the terminal. This device, capable of implementing the failover control method which has just been described in all its embodiments, is intended to be implemented in an SDN network controller.

The invention also relates to a computer program comprising instructions which, when these instructions are executed by a processor, lead the latter to implement the steps of the failover management method, which has just been described. The invention also relates to an information medium readable by a physical access point of a Wi-Fi network, and comprising instructions of a computer program as mentioned above.

The invention further relates to a computer program comprising instructions which, when these instructions are executed by a processor, lead the latter to implement the steps of the changeover control method, which has just been described.

The invention also relates to an information medium readable by a controller of an SDN network, and comprising instructions of a computer program as mentioned above.

The programs mentioned above can use any programming language, and be in the form of source code, object code, or code intermediate between source code and object code, such as in a partially compiled form, or in n any other desirable shape.

The information carriers mentioned above can be any entity or device capable of storing the program. For example, a medium can comprise a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or else a magnetic recording means. Such a storage means can for example be a hard disk, a flash memory, etc. On the other hand, an information medium can be a transmissible medium such as an electrical or optical signal, which can be conveyed via an electrical or optical cable, by radio or other means. A program according to the invention can in particular be downloaded from an Internet type network.

Alternatively, an information medium can be an integrated circuit in which a program is incorporated, the circuit being adapted to execute or to be used in the execution of the methods in question.

4. Presentation of figures

Other advantages and characteristics of the invention will emerge more clearly on reading the following description of a particular embodiment of the invention, given by way of simple illustrative and non-limiting example, and the appended drawings, among which :

[Fig 1] Figure 1 schematically shows a first example of a Wi-Fi network using a virtual access point and two physical access points,

[Fig 2] FIG. 2 shows an example of the implementation of the methods for managing and controlling the switching of a terminal between physical access points in a Wi-Fi network using a virtual access point, according to a aspect of the invention,

[Fig 3] Figure 3 schematically shows a second example of a Wi-Fi network using a virtual access point and two physical access points,

[Fig 4] FIG. 4 shows an example of the structure of a management device implementing the method for managing the switchover of a terminal between physical access points in a Wi-Fi network using an access point virtual, according to one aspect of the invention,

[Fig 5] FIG. 5 shows an example of the structure of a control device implementing the method for controlling the switching of a terminal between physical access points in a Wi-Fi network using an access point virtual, according to one aspect of the invention.

5. Detailed description of at least one embodiment of the invention In the remainder of the description, examples of embodiments of the invention based on a so-called Wi-Fi network are presented, but it is understood that the invention applies to all the variations of the IEEE 802.11 standards.

FIG. 2 shows an example of the implementation of the methods for managing and controlling the switchover of a terminal between physical access points in a Wi-Fi network using a virtual access point, according to one aspect of the invention.

It is known that when a station associates with a Wi-Fi access point, the parameters describing the capacities which are specific to the station are included in 2 types of messages that it sends: Probe Request and Association Request . An access point receiving a Probe Request responds, using a Probe Response message, with its own parameters describing its own capabilities, which allows the station to indicate in the Association Request the subset of its parameters that it wishes to use for an association with this access point.

During a step 1001, the terminal STA is located near the physical access point AP1, and sends a request PRq of the Probe Request type, comprising parameters among the following, which are information relating to the capacities of the terminal:

• "HT capabilities" for 802.11n;

• "VHT capabilities" for 802.11ac;

• "HE capabilities" for 802.11ax;

• MAC address of the STA terminal.

During a step 1002, the access point AP1 receives the request PRq and extracts the above parameters therefrom.

The access point AP1, like the access point AP2, is part of a plurality of access points of a Wi-Fi network of SDN type, where each access point is connected to a SDN network controller, here called CTL.

During a step 1003, the access point AP1 transmits to the controller CTL an LVAP-CrRq request for creation of a virtual access point, comprising an identifier of AP1 of SSID type, the MAC address of the terminal STA, to allow the controller CTL to create for the access point AP1 an LVAP access point identifier which is unique to the terminal STA. Advantageously, and unlike the prior art, the LVAP-CrRq application further comprises the parameters representative of the capacities of the STA terminal, extracted during step 1002.

During a step 1004, the controller CTL receives the LVAP-CrRq request for creation of a virtual access point, and stores in a table or an STA-info register the parameters representative of the capacities of the terminal STA, identified by its MAC address. During this step, the controller also creates a virtual access point LVAP identifier, of BSSID type, dedicated to the terminal STA, and unique to the latter. For example the LVAP identifier is formed on the basis of the first 3 bytes of the MAC address of the physical access point and of the last 3 bytes of the MAC address of the STA terminal, and / or is the product of a hash the MAC address of the STA terminal, the main thing being that the LVAP identifier is unique in the network of the Wi-Fi network.

During a step 1005, the controller CTL responds to the access point AP1 by sending it an LVAP-CrRp message comprising the LVAP identifier. The access point AP1 receives this message during a step 1006, and assigns itself the LVAP identifier as the BSSID identifier.

During a step 1007, the access point AP1 sends its response PRp to the Probe Request received during step 1002. The response PRq includes the BSSID assigned to the access point AP1, which is LVAP. The terminal receives this response and can then use this BSSID. There follow exchanges between the terminal STA and the access point AP1, known and not illustrated, to authenticate the terminal STA and associate it with the access point AP1. Thanks to these exchanges, during a step 1008, the terminal STA is associated with the physical access point AP1 with LVAP as BSSID. Optionally, during this phase, the physical access point AP1 can extract information relating to the capacities of the terminal STA from an Association Request type message sent by the latter. The physical access point AP1 can then transmit them to the controller CTL so that it knows the configuration used for the connection between the terminal STA and the access point AP1.

A phase of use of the access point AP1 by the terminal STA follows, in which data packets are exchanged between the terminal and the network to which the access point AP1 gives access, not shown. For some of these packets, in a known manner, the access point AP1 consults the controller CTL to determine the routing of the packets, for example using requests / responses of the Packetln / PacketOut type from Openflow.

During this phase of use, in a known manner, the access point AP1 measures the quality of the connection established with the terminal STA, for example by measuring the power of the signal received from the terminal STA ("RSSI", Received Signal Strength Indication , or indication of received signal strength, in English). The access point AP1 transmits to the controller CTL one or more reports comprising this measurement. Other measurements than the signal strength can be used, such as the usage time of the radio channel, or an indicator corresponding to the load (occupancy rate of the radio channel, "BSS load", etc.) of the AP .

The signal emitted by the STA terminal is also perceived by AP2, another Wi-Fi access point of the SDN network. The AP2 access point is configured to perform the same type of measurement as the AP1 access point, and transmits the same type of measurement reports to the CTL controller. At any time after step 1008 (where the terminal STA is associated with the physical access point AP1 with LVAP as the BSSID), on the basis of the measurement reports that it has received, the controller CTL determines during a step 1009 that the connection between the access point AP1 and the terminal STA is no longer optimal, according to a determined switchover criterion. This switching criterion is preferably related to the measurements received and with a predetermined quality threshold that a measurement received must or must not exceed. For example, the power of the signal received from the terminal STA by the access point AP1 has become less than -75 dBm. Other failover criteria can be used, such as a BSS load greater than 75%.

During this step 1009, the controller CTL, which has also received measurement reports from other physical access points of the SDN network, detects that the access point AP2 satisfies the switchover criterion.

These changes in the values of the measurements used by the controller can for example simply be the result of a mobility of the terminal STA, which has moved away from the access point AP1 to approach the access point AP2, or the result a more complex change of situation, such as the occurrence of radio interference in the radio channel used by GAR1, or the need to prioritize flows from another station also connected to the access point AP1.

During a step 1010 comprising several sub-steps, on the basis of the switching criterion, the controller CTL moves from the access point AP1 to the access point AP2 the LVAP identifier as well as its characteristics, its routing rules. , and the terminal attachment. To do this, the controller CTL sends to the access point AP1 an LVAP-Del request to delete the BSSID LVAP, and sends to the access point AP2 an LVAP-Add request to add the BSSID LVAP. Corresponding acknowledgment messages, not shown, are also transmitted. The result of this step 1010 is the step 1011, where the terminal STA is still associated with the BSSID LVAP, but this BSSID is now carried by the physical access point AP2, and no longer the physical access point AP1. In a transparent manner for the terminal STA, the first connection between the terminal STA and the access point AP1 has switched to a second connection between the terminal STA and the access point AP2.

One of the advantageous features of the invention is that the controller CTL knows both the capacities of the terminal STA, and those of the various physical access points of the SDN network that it controls. The latter, for example, were communicated to it during the initial configuration of the SDN network of Wi-Fi access points, automatically or manually.

The controller CTL can therefore ensure that the switching takes advantage of the respective capacities of the terminal STA and of the arrival access point AP2.

Three mutually exclusive cases exist. In a first case, the capacities of the arrival access point are greater than those of the departure access point, and the second connection must be reconfigured, during a step 1010post. In a second case, the capacities of the terminating access point are lower than those of the originating access point, and the first connection must be reconfigured before the switchover, during a step 1010pre. Finally, in a third case, the capacities of the two access points are equivalent, and no reconfiguration is necessary.

In the first case, after step 1010 and preferably after step 1011, step 1010post comprises the transmission of a reconfiguration message of the second connection, from the controller CTL to the access point AP2. For example, the AP1 access point can use the 80MHz band but not the 160MHz band, while the STA terminal and the AP2 access point can use both bands. The first connection therefore used the 80MHz band. The second connection, on failover, continues to use that same band. Thanks to the message sent during step 1010post, the second connection is reconfigured to use the 160 MHz band. In the second case, step 1010pre precedes step 1010 and comprises sending a message for reconfiguring the first connection, from the controller CTL to the access point AP1. For example, the AP2 access point can use the 80MHz band but not the 160MHz band, while the STA terminal and the AP1 access point can use both bands. The first connection therefore used the 160MHz band. The second connection, after failover, if nothing was done, would attempt unsuccessfully to use that same band and would be terminated. Thanks to the message sent during step 1010pre, the first connection is reconfigured in anticipation of the switchover to use the 80 MHz band and thus prepare a switchover without interruption.

The reconfiguration of a connection between a station and its access point can be carried out in several ways. If the reconfiguration consists in switching from one IEEE 802.11 standard to another, or from one version to another of these standards, the messages received by the access point or by the station are defined by these standards. For example, on the order of the controller, the access point sends a CSA (Channel Switch Announcement) message to the station. If the reconfiguration consists in modifying a radio channel without replacing it by another (for example to modify the width of the frequency band used by the access point, while remaining in the same variation of the IEEE 802.11 standard), messages specific to the equipment considered may be necessary, such as for example an order to deactivate and reactivate OFDMA or Mu-MIMO in the antennas.

If we take the example of Figure 1, we understand that thanks to the invention the Wi-Fi connection of a terminal which is moving between access points offering different capacities will always remain optimal and will not be not interrupted, unlike the prior art. There are other situations where the invention finds its application, an example of which is illustrated in FIG. 3. With reference to FIG. 3, initially, the two terminals STA1 and STA2 are associated, independently of one another, with the same physical access point AP1, each with the access point identifier virtual dedicated to them, respectively LVAP1 and LVAP2.

As in the first example in figure 1, IΆR1 supports Wi-Fi 5 (IEEE 802.11ac radio standard), in the 5 GHz band with a maximum bandwidth of 80 MHz (this is the minimum required by the standard IEEE 802.11ac). The AP2 also supports Wi-Fi 5, in the 5 GHz band but with a maximum bandwidth of 160MHz (this feature is optional in the IEEE 802.11ac standard). For the moment, IΆR2 is deactivated.

The STA1 terminal supports Wi-Fi 5 with 80 MHz, while the STA2 terminal supports Wi-Fi 5 with 160 MHz. Each of their respective connections with the physical access point AP1 will therefore use the 80 MHz band.

Secondly, the AP2 access point is activated and is added to the Wi-Fi network controlled by the CTL controller. The two terminals STA1 and STA1, which have not changed their position, are then in the area covered by the physical access point AP2, in addition to being in that of AP1. The controller CTL, thanks to the changeover management method according to the invention, knows the respective capacities of the terminals STA1 and STA2, and the capacities of the physical access point AP2. It can then determine that the physical access point AP2 would be optimal for the terminal STA2, so that it takes advantage of its capacities for using the 160 MHz band, and proceeds to switch from the terminal STA2 to IΆR2 while keeping it associated with the BSSID LVAP2.

It is understood that the examples which have just been described representing only a few of the embodiments of the invention, and that the invention applies to any Wi-Fi network using a virtual access point ( LVAP) managed by an SDN network controller, regardless of the number of physical access points and the number of stations (terminals, mobile or not) associated with it, and regardless of the order in which the physical access points are activated or deactivated.

In relation to FIG. 4, an example of the structure of a management device implementing the method for managing the switchover of a terminal between physical access points in a Wi-Fi network using a point of access is now presented. virtual access, according to one aspect of the invention.

The management device 100 implements the failover management method, of which various embodiments have just been described.

Such a device 100 can be implemented in a physical access point, such as for example the access point AP1, called the first physical access point, or the access point AP2, called the second access point. physical.

For example, the device 100 comprises a receiver 101, a transmitter 102, a processing unit 130, equipped for example with an mR microprocessor, and controlled by a computer program 110, stored in a memory 120 and implementing the failover management method according to the invention. On initialization, the code instructions of the computer program 110 are for example loaded into a RAM memory, before being executed by the processor of the processing unit 130. Such a memory 120, such a processor of the 'processing unit 130, such a receiver 101 and such a transmitter 102 are capable of, and configured for:

• transmit, from the first physical access point to the controller, iLVAP-CrRq information relating to the capacities of the terminal,

• receive an LVAP-Del or LVAP-Add order to switch from a first connection between the terminal and the first physical access point to a second connection established between the terminal and a second physical access point using the same identifier virtual access point, the first and the second connection being adapted to the capacities of the terminal.

Advantageously, they are also suitable for, and configured for:

• extract information relating to the capabilities of the terminal from a message Probe Request type PRq sent by the terminal and received by the first physical access point,

• transmit the information relating to the capabilities of the terminal to an SDN controller in an LVAP-CrRq message requesting the creation of a virtual access point,

• receive an m1010pre order to reconfigure the first connection, prior to switching if the capacities of the second physical access point are lower than those of the first,

• receive an m1010post order to reconfigure the second connection, following the switchover if the capacities of the second physical access point are greater than those of the first.

Optionally, they are also suitable for, and configured for:

• extract the information relating to the capabilities of the terminal from an Association Request type ARq message sent by the terminal and received by the first physical access point.

In relation to FIG. 5, an example of the structure of a control device implementing the method for controlling the switching of a terminal between physical access points in a Wi-Fi network using a point of access is now presented. virtual access, according to one aspect of the invention.

The control device 200 implements the tilting control method, various embodiments of which have just been described.

Such a device 200 can be implemented in an SDN network controller, such as for example the CTL controller.

For example, the device 200 comprises a receiver 201, a transmitter 202, a processing unit 230, equipped for example with an mR microprocessor, and controlled by a computer program 210, stored in a memory 220 and implementing the control method according to the invention. On initialization, the code instructions of the computer program 210 are for example loaded into a RAM memory, before being executed by the processor of the processing unit 230. Such a memory 220, such a processor of the processing unit 230, such a receiver 201 and such a transmitter 202 are capable of, and configured for:

• receive, from a first physical access point, iLVAP-CrRq information relating to the capacities of a terminal,

• store said information in memory 220, for example in a table or an STA-Info register,

• assign a virtual access point identifier to the first physical access point, dedicated to the terminal,

• and, according to a determined criterion, trigger the switchover from a first connection between the terminal and the first physical access point to a second connection between the terminal and a second physical access point using the same point virtual access, the first and the second connection being adapted to the capacities of the terminal, by issuing LVAP-Del and LVAP-Add switching orders respectively to the first physical access point and the second physical access point.

Advantageously, they are also suitable for, and configured for:

• receive information on the capabilities of the terminal in an mLVAP-CrRq message requesting the creation of a virtual access point sent by the first physical access point,

• send an m1010pre order to reconfigure the first connection to the first physical access point, prior to switching if the capacities of the second physical access point are lower than those of the first,

• send an m1010post order to reconfigure the second connection to the second physical access point, following the switchover if the capacities of the second physical access point are greater than those of the first.

The entities described and included in the devices described in relation to FIGS. 4 and 5 can be hardware or software. Figures 4 and 5 illustrate only one particular way, among several possible, of carrying out the algorithm detailed above, in relation with FIG. 2. In fact, the technique of the invention is carried out indifferently on a reprogrammable computing machine (a PC computer, a DSP processor or a microcontroller) executing a program comprising a sequence of instructions, or on a dedicated computing machine (for example a set of logic gates such as an FPGA or an ASIC, or any other hardware module).

In the case where the invention is implemented on a reprogrammable computing machine, the corresponding program (that is to say the sequence of instructions) can be stored in a removable storage medium (such as for example a USB key , a floppy disk, a CD-ROM or a DVD-ROM) or not, this storage medium being partially or totally readable by a computer or a processor.

Claims

1. Method for managing the switchover of a terminal (STA) between a plurality of physical access points (AP1, AP2) to a Wi-Fi network, a virtual access point identifier (LVAP) dedicated to the terminal being assigned by a controller (CTL) to a first physical access point (AP1), the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the method comprising at the first access point:

• transmit (1003), from the first physical access point to the controller, information relating to the capabilities of the terminal,

• receive (1010) an order to switch from the first connection to a second connection established between the terminal and a second physical access point (AP2) of the plurality using the same virtual access point identifier, the first and the second connection being adapted to the capacities of the terminal.

2. Management method according to claim 1, comprising an extraction (1002) of the information relating to the capabilities of the terminal from a message (PRq) of the Probe Request type sent (1001) by the terminal and received (1002). through the first physical access point.

3. Management method according to one of claims 1 to 2, where the information relating to the capabilities of the terminal is transmitted to the controller in a message (LVAP-CrRq) requesting the creation of a virtual access point.

4. Management method according to one of claims 1 to 3, comprising a reconfiguration (1010pre) of the first connection, prior to switching if the capacities of the second physical access point are lower than those of the first.

5. Management method according to one of claims 1 to 3, comprising reconfiguration (1010post) of the second connection, following the switchover if capacities of the second physical access point are greater than those of the first.

6. Method for controlling the switchover of a terminal (STA) between a plurality of physical access points (AP1, AP2) to a Wi-Fi network, a virtual access point identifier (LVAP) dedicated to the terminal being assigned by a controller (CTL) to a first physical access point (AP1), the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the method comprising at the level of the controller:

• receive (1004), from the first physical access point, information relating to the capacities of the terminal,

• and, according to a determined criterion, trigger (1009) the switching of the first connection to a second connection established between the terminal and a second physical access point (AP2) of the plurality using the same point of virtual access, the first and the second connection being adapted to the capacities of the terminal.

7. The control method according to claim 6, wherein the information relating to the capabilities of the terminal is transmitted to the controller in a message (LVAP-CrRq) requesting the creation of a virtual access point sent by the first point of access. physical access.

8. Control method according to one of claims 6 to 7, comprising the transmission (1010pre) to the first physical access point of an order for reconfiguration of the first connection, prior to switching if the capacities of the second point. of physical access are lower than those of the first.

9. The control method according to one of claims 6 to 7, comprising the transmission (1010post) to the second physical access point of an order for reconfiguration of the second connection, following the switchover if the capacities of the second point. of physical access are greater than those of the first.

10. Device for managing the switchover of a terminal (STA) between a plurality of physical access points (AP1, AP2) to a Wi-Fi network, a virtual access point identifier (LVAP) dedicated to the terminal being assigned by a controller (CTL) to a first physical access point (AP1), the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the device comprising a receiver (101), a transmitter (102), a processor (130), and a memory (120) coupled to the processor with instructions to be executed by the processor to:

• transmit, from the first physical access point to the controller, information (iLVAP-CrRq) relating to the capacities of the terminal,

• receive an order (LVAP-Del; LVAP-Add) to switch the first connection to a second connection established between the terminal and a second physical access point (AP2) of the plurality using the same point identifier virtual access, the first and the second connection being adapted to the capacities of the terminal.

11. Device for controlling the switchover of a terminal (STA) between a plurality of physical access points (AP1, AP2) to a Wi-Fi network, a virtual access point identifier (LVAP) dedicated to the terminal being assigned by a controller (CTL) to a first physical access point (AP1), the terminal associating with the first physical access point by a first connection using the virtual access point identifier, the device comprising a receiver (201), a transmitter (202), a processor (230), and a memory (220) coupled to the processor with instructions to be executed by the processor to:

• receive, from the first physical access point, information (iLVAP-CrRq) relating to the capacities of the terminal,

• store said information in memory,

• and, according to a determined criterion, trigger the switch from the first connection to a second connection established between the terminal and a second physical access point of the plurality using the same virtual access point, the first and the second connection being adapted to the capabilities of the terminal.

12. A computer program, comprising instructions which, when these instructions are executed by a processor, lead the latter to implement the steps of the failover management method, according to claim 1.

13. A computer program, comprising instructions which, when these instructions are executed by a processor, lead the latter to implement the steps of the changeover control method, according to claim 6.

14. Information medium readable by a physical access point of a Wi-Fi network (AP1; AP2), and comprising instructions of a computer program in accordance with claim 12.

15. Information medium readable by a controller of an SDN network (CTL), and comprising instructions of a computer program according to claim 13.