Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/16—Performing reselection for specific purposes
  • H04W36/18—Performing reselection for specific purposes for allowing seamless reselection, e.g. soft reselection
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W8/00—Network data management
  • H04W8/22—Processing or transfer of terminal data, e.g. status or physical capabilities
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W48/00—Access restriction; Network selection; Access point selection
  • H04W48/18—Selecting a network or a communication service
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
  • H04W84/10—Small scale networks; Flat hierarchical networks
  • H04W84/12—WLAN [Wireless Local Area Networks]

Definitions

• 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) .
• LVAP virtual access point
• SDN Service Defined Network, in English
• 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.
• a terminal also called a station
• AP physical access points
• Outgoing AP to the incoming AP the LVAP virtual access point identifier, with its characteristics, routing rules, and terminal attachment.
• 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.
• 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.
• a Wi-Fi station 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 I ⁇ R1, its Wi-Fi connection ends up switching from I ⁇ R1 to I ⁇ R2. 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 I ⁇ R2 and of the STA station. The resulting quality enjoyed by the station is lower, but the connection will still work.
• the STA station Conversely, if the STA first associates with I ⁇ R2 then switches to I ⁇ R1, 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 I ⁇ R1, 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.
• One of the aims of the invention is to remedy these drawbacks of the state of the art.
• 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:
• 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.
• 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.
• the terminal continues to send its data frames with the same recipient identifier, and does not see that the physical access point has changed.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• a virtual access point identifier dedicated to the terminal it is in this request that the parameters relating to the capacities of the terminal are transmitted.
• 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.
• the second connection is not interrupted.
• 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.
• lower capacity or “higher capacity” is meant a resulting lower quality, respectively a resulting higher quality, of operation of the equipment under consideration.
• 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.
• 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:
• 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.
• 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.
• 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.
• 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:
• 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.
• 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.
• a storage means can for example be a hard disk, a flash memory, etc.
• 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.
• 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.
• Figure 1 schematically shows a first example of a Wi-Fi network using a virtual access point and two physical access points
• 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 schematically shows a second example of a Wi-Fi network using a virtual access point and two physical access points
• 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 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.
• 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.
• Probe Request 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.
• 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:
• the access point AP1 receives the request PRq and extracts the above parameters therefrom.
• the access point AP1 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.
• 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.
• the LVAP-CrRq application further comprises the parameters representative of the capacities of the STA terminal, extracted during step 1002.
• 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.
• the controller also creates a virtual access point LVAP identifier, of BSSID type, dedicated to the terminal STA, and unique to the latter.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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%.
• 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.
• 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.
• step 1010 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.
• 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.
• 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.
• 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.
• 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.
• the capacities of the two access points are equivalent, and no reconfiguration is necessary.
• step 1010post comprises the transmission of a reconfiguration message of the second connection, from the controller CTL to the access point AP2.
• 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.
• step 1010pre precedes step 1010 and comprises sending a message for reconfiguring the first connection, from the controller CTL to the access point AP1.
• 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.
• CSA Channel Switch Announcement
• 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.
• 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.
• I ⁇ R1 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, I ⁇ R2 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.
• 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 I ⁇ R2 while keeping it associated with the BSSID LVAP2.
• 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.
• 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.
• 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.
• 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:
• 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.
• 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.
• a computer program 210 stored in a memory 220 and implementing the control method according to the invention.
• 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:
• 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.
• 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).
• a reprogrammable computing machine a PC computer, a DSP processor or a microcontroller
• a program comprising a sequence of instructions
• a dedicated computing machine for example a set of logic gates such as an FPGA or an ASIC, or any other hardware module.
• 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.
• a removable storage medium such as for example a USB key , a floppy disk, a CD-ROM or a DVD-ROM

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• 2019
  • 2019-12-20 FR FR1915206A patent/FR3106950A1/fr active Pending
• 2020
  • 2020-12-14 US US17/786,895 patent/US20230034345A1/en active Pending
  • 2020-12-14 CN CN202080095125.0A patent/CN115053550A/zh active Pending
  • 2020-12-14 EP EP20845189.8A patent/EP4079013A1/de active Pending
  • 2020-12-14 WO PCT/FR2020/052405 patent/WO2021123582A1/fr unknown

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