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WO2025233307A1 - Dispositif de commande, dispositif à liaisons multiples, point d'accès et procédés - Google Patents

Dispositif de commande, dispositif à liaisons multiples, point d'accès et procédés

Info

Publication number
WO2025233307A1
WO2025233307A1 PCT/EP2025/062274 EP2025062274W WO2025233307A1 WO 2025233307 A1 WO2025233307 A1 WO 2025233307A1 EP 2025062274 W EP2025062274 W EP 2025062274W WO 2025233307 A1 WO2025233307 A1 WO 2025233307A1
Authority
WO
WIPO (PCT)
Prior art keywords
mld
link
control device
request
circuitry
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2025/062274
Other languages
English (en)
Inventor
Thomas Handte
Dana CIOCHINA-KAR
Daniel VERENZUELA
Ken Tanaka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sony Europe BV United Kingdom Branch
Sony Group Corp
Original Assignee
Sony Europe Ltd
Sony Group Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sony Europe Ltd, Sony Group Corp filed Critical Sony Europe Ltd
Publication of WO2025233307A1 publication Critical patent/WO2025233307A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0033—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information
    • H04W36/0038—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information of security context information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0033—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information
    • H04W36/0044—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information of quality context information
    • 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
    • H04W36/16—Performing reselection for specific purposes
    • H04W36/18—Performing reselection for specific purposes for allowing seamless reselection, e.g. soft reselection
    • H04W36/185—Performing reselection for specific purposes for allowing seamless reselection, e.g. soft reselection using make before break
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H04W36/0069—Transmission or use of information for re-establishing the radio link in case of dual connectivity, e.g. decoupled uplink/downlink
    • 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]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Definitions

  • the present disclosure relates to control device, a multi-link device (MLD) and an access point (AP) as well as corresponding methods, in particular for use in a wireless communication system.
  • MLD multi-link device
  • AP access point
  • a communication device e.g. a station (STA)
  • the connectivity to another communication device e.g. an access point (AP)
  • AP access point
  • a control device configured to control the routing of data units between a distribution system and one of two or more access points (APs), each being configured to communicate with a multi-link device (MLD) via a separate link
  • the control device comprising circuitry configured to: receive a request from the MLD or the first AP to add a second link between the MLD and a second AP while a first link between the MLD and a first AP is enabled; transmit, to the second AP, first context information configured for use by the second AP to communicate with the MLD; and add the second link and notify the MLD of the addition of the second link.
  • a multi-link device configured to communicate with one or more access points (APs) via separate links
  • the MLD comprising circuitry configured to: transmit a request to a control device to add a second link between the MLD and a second AP while a first link between the MLD and a first AP is enabled; and receive a notification from the control device or the second AP regarding the addition of the second link.
  • an access point configured to communicate with a multi-link device (MLD) via a first link
  • the MLD being configured to communicate with one or more access points via separate links and to communicate with a control device
  • the AP comprising circuitry configured to: receive a request from the MLD or generate a request to add a second link between the MLD and a second AP while a first link between the MLD and a first AP is enabled; transmit the request to the control device; and receive a notification from the control device and/or the second AP regarding the addition of the second link; and transmit the notification to the MLD.
  • a computer program comprising program means for causing a computer to carry out the steps of the method disclosed herein, when said computer program is carried out on a computer, as well as a non-transi- tory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the respective methods disclosed herein to be performed are provided.
  • One of the aspects of the disclosure is the use of a framework leveraging multi-link operation which can provide almost seamless roaming.
  • An entity referred to as control device herein, that is separated from a particular AP and to which a STA (the MLD) associates once, is provided according to the present disclosure.
  • the control device provides the necessary information to the new serving AP (the second AP) and the for- merly serving AP (the first AP) transfers a minimum of information to the newly serving AP.
  • DS distribution system
  • the expression “separate link” shall be understood such that the links are separate in the sense that they are managed or created by different APs, but both links may or may not be on the same carrier frequency. Further, it shall be understood that an “enabled link” allows exchange of management and control data units and that an “activated link” allows exchange of user data units on top of the exchange of management and control data units.
  • Fig. 1 shows a schematic diagram of a first embodiment of a communication system according to the present disclosure.
  • Fig. 2 shows a schematic diagram of a second embodiment of a communication system according to the present disclosure.
  • Fig. 3 shows a schematic diagram of a third embodiment of a communication system according to the present disclosure.
  • Fig. 4 shows a schematic diagram of a fourth embodiment of a communication system according to the present disclosure.
  • Fig. 5 shows a schematic diagram of a fifth embodiment of a communication system according to the present disclosure.
  • Fig. 6 shows a schematic diagram of a sixth embodiment of a communication system according to the present disclosure.
  • Fig. 7 shows a diagram of an embodiment of an association operation according to the present disclosure.
  • Fig. 8 shows a diagram of another embodiment of an association operation according to the present disclosure.
  • Fig. 9 shows a diagram of an embodiment of data transfer operation according to the present disclosure.
  • Fig. 10 shows a diagram of an embodiment of an on-boarding operation according to the present disclosure.
  • Fig. 11 shows a diagram of an embodiment of an activation operation according to the present disclosure.
  • Fig. 12 shows a diagram illustrating an exemplary data flow during the roaming procedure.
  • Fig. 13 shows a diagram of another embodiment of an activation operation according to the present disclosure.
  • Fig. 14 shows a diagram illustrating buffer flushing in the context of the present disclosure.
  • Fig. 15 shows a diagram illustrating a first embodiment to resolve the issue of flushing buffer illustrated in Fig. 14.
  • Fig. 16 shows a diagram illustrating a second embodiment to resolve the issue of flushing buffer illustrated in Fig. 14.
  • Fig. 17 shows a diagram illustrating a third embodiment to resolve the issue of flushing buffer illustrated in Fig. 14.
  • Fig. 18 shows a diagram illustrating a first embodiment to resolve the issue of flushing buffer in UL.
  • Fig. 19 shows a diagram illustrating a second embodiment to resolve the issue of flushing buffer in UL.
  • Fig. 20 shows a flow chart of an embodiment of a control method according to the present disclosure.
  • Fig. 21 shows a flow chart of an embodiment of a first communication method according to the present disclosure.
  • Fig. 22 shows a flow chart of an embodiment of a second communication method according to the present disclosure.
  • the present disclosure may be applied in mobile scenarios, in which the connectivity of a moving station (STA) to an access point (AP) may get lost due to too strong path loss.
  • STA moving station
  • AP access point
  • a STA typically associates with or roams to a different AP belonging to the same extended service set (ESS) in due time, which may take time for regeneration of (encryption I decryption) keys and renegotiation of agreements (such as Block Acknowledgement (Back) agreement) and prevents data transfer during this time.
  • ESS extended service set
  • ESS extended service set
  • ESS extended service set
  • ESS extended service set
  • renegotiation of agreements such as Block Acknowledgement (Back) agreement
  • the present disclosure makes use of a distribution system (DS) for routing the data flows and a control entity (CE; also referred to as control device herein).
  • CE controls multiple APs and the DS.
  • the solution is to provide an architecture for seamless roaming, i.e. , the non-AP multi-link device (MLD) stays in a certain state that allows exchange of data units (referred to as state 4 below) regardless if changing the serving AP but may not be able to provide connectivity to/from multiple APs at the same time.
  • MLD non-AP multi-link device
  • Figs. 1 and 2 show schematic diagrams of a first and second embodiment of a communication system according to the present disclosure.
  • the control entity (CE) 10 is a device that resides in the same network as at least two APs 20 (AP1) and 30 (AP2). Physically, the CE 10 may be attached to an AP 20, 30 or may be a separate device within the network. It is connected to either at least two APs 20, 30, as shown in Fig. 1 , or to a CE of at least one more APs, e.g., to AP1 20 as shown in Fig. 2.
  • the CE 10 When the CE 10 is attached to an AP, it may have an internal link to the attached AP and a network link (backhaul) to other APs or a CE of other APs.
  • the CE 10 and the APs 20, 30 exchange configuration information (i.e. non-user data information) as shown in Fig. 1.
  • Both APs 20, 30 establish links 101 , 102 (link 1 and link 2) to STAs 40 (STA1) and 50 (STA2).
  • STAs 40, 50 are organized in a non-AP multi-link device (MLD) 60.
  • the non-AP MLD 60 converges the traffic flows of the two STAs 40, 50 within a device.
  • the CE 10 may control both APs 20, 30 via their station management entity (SME) 21 , 31 as shown in Fig. 3 depicting a schematic diagram of a third embodiment of a communication system according to the present disclosure.
  • CE 10 and APs 20, 30 are connected via a wired or wireless or hybrid communication link 107, 108.
  • the connection may also use the same or a different distribution system (DS) 70 as for the user data transfer.
  • DS distribution system
  • the APs 20, 30 are connected to the DS, e.g., via wired or wireless or hybrid com- munication links 103, 104.
  • the CE 10 is connected to the DS, e.g., via wired or wireless or hybrid communication link 106.
  • Fig. 4 shows a schematic diagram of a fourth embodiment of a communication system according to the present disclosure, where instead of a single CE, each AP 20, 30 holds a CE 11 , 12.
  • the CE controls the DS and may change the mapping (or routing) of data packets (e.g. MAC Service Data Units; MSDUs) for the non-AP MLD 60 to a particular AP 20 or 30.
  • data packets e.g. MAC Service Data Units; MSDUs
  • MSDUs MAC Service Data Units
  • the CE may change the DS mapping during operation.
  • the CE 10 generally has a Medium Access Control (MAC) address. Any frame addressed to the CE 10 identified via its MAC address will be forwarded to the CE 10 by an AP 20 or 30.
  • the MAC address is important for association and encryption key generation, including a temporal key (TK).
  • No (user) data frame is addressed to the CE’s MAC address.
  • each AP 20, 30 may come with its own CE, i.e. , a CE 11 of AP 20 may have the same MAC address as another CE 12 of AP 30, particularly if it is ensured that the non-AP MLD 60 connects to a unique CE.
  • the non-AP MLD 60 can only connect to a CE which belongs to the AP through which the non-AP MLD 60 is connected to the DS 70 as shown in Fig. 4.
  • the assumption is that both CEs 11, 12 may be logically connected and can exchange non-user data which would be also possible via the DS 70 (e.g., as shown in Fig. 5).
  • both CEs 11, 12 can configure the DS mapping for which reason both are connected to the DS 70 via links 106, 107, respectively.
  • the AP 20 currently serving the non-AP MLD 60 holds context information 200 (also referred to as context), as shown in Figs. 3, 4 or 5.
  • the context information 200 is information important for transmission or reception of data frames. Without context information, a frame exchange may not happen or may not be successful.
  • the context information contains at least information about sequence numbers (SN) and packet number (PN).
  • the (complete) context information 200 i.e., including first and second context information (as explained below), may include one or more of the following information: a reset indication of PN and/or SN; for instance, for SN this means restarting at 0 and for PN this means using a higher PN than before (e.g.
  • PN may not repeat for the same TK
  • the current PN and/or SN encryption keys, e.g., a pairwise transient key (PTK) and/or a group temporal key (GTK); association/capability data including Physical Layer (PHY) and/or MAC capabilities of AP and/or non-AP STA to determine common communication features that can be used; negotiated agreements including mechanisms configured for an AP - non-AP pair to improve data transfer such as a BlockAck agreement, target wake time (TWT) agreement, etc.;
  • BAck scoreboard content of a scoreboard maintained at a receiver side and holding information about successfully and erroneously received data units indexed by SN; receive buffer including successfully received data units which have not yet been forwarded to higher layer, e.g., due to an erroneous data unit with lower SN; and transmit buffer including data units which have not yet been transmitted, e.g., due to a channel busy condition.
  • the context information can be transferred between two APs 20, 30 via a direct link 100 as shown in Figs. 3 to 4. Thereby, it may be exchanged directly between the APs (Fig. 3) or between the CEs of the APs (Fig. 3 or Fig. 4) or it may be exchanged between APs 20, 30 via the DS 70 as shown in Fig. 5 depicting a schematic diagram of a fifth embodiment of a communication system according to the present disclosure, where the connection between the APs 20, 30 and the CE 10 is established via the same DS 70 that is used for user data transfer While Figs. 3 to 5 show the roaming architecture for two APs, Fig. 6, depicting a schematic diagram of a sixth embodiment of a communication system according to the present disclosure, shows the roaming architecture for two AP MLDs.
  • a CE generally knows all APs that a non-AP MLD may potentially use during roaming.
  • the CE authenticated all those APs.
  • the CE can securely communicate with those APs.
  • the CE is aware of capabilities (i.e., supported features) of each AP. These steps may happen before the following process for all APs or on a step-by-step basis, i.e., successively onboarding of new APs during setup or on demand basis.
  • the connection between the AP and the CE may be via the DS or via an internal interface if the AP and CE reside in same device as e.g. shown in Fig. 2.
  • Fig. 7 shows a diagram of an embodiment of an association operation according to the present disclosure.
  • a non-AP MLD 60 detects an AP, in this example AP1 20, via reception of a beacon frame of said AP (not shown in Fig. 7).
  • This beacon frame contains not only the MAC address of the AP but also of the CE 10.
  • the non-AP LD 60 authenticates and associates with the CE 10 via an AP 20 (AP1 in this embodiment).
  • the authentication request and authentication response frame exchange 300 (“authentication operation” or simply “authentication”) includes the transmission of an authentication request 301 , 302 from the MLD 60 via the AP1 20 (and link 101) to the CE 10 and the transmission of an authentication response 303, 304 from the CE 10 via the AP1 20 (and link 101) to the non-AP MLD 60.
  • This authentication operation 300 may be used to authenticate the non-AP MLD 60 in various ways.
  • the authentication is often “open system” meaning that it is essentially disabled, because authentication happens with the “802.1X authentication” mechanism 330 as explained below.
  • the subsequent association request and association response frame exchange 310 (“association operation” or simply “association”) includes the transmission of an association request 311, 312 from the non-AP MLD 60 via the AP1 20 (and link 101) to the CE 10 and the transmission of an association response 313, 314 from the CE 10 via the AP1 20 (and link 101) to the non-AP MLD 60.
  • the association request 311 , 312 holds the capabilities of the non-AP MLD 60
  • the association response 313, 314 holds the capabilities of the AP1 20.
  • the association response 313, 314 may hold capabilities of other (e.g. neighboring) APs to which the CE 10 is or may be connected in future.
  • basic capabilities are contained in the association response 313, 314 indicating a minimum set of capabilities which are supported by any APs which are or may be connected to the CE 10.
  • the CE 10 either forwards the capabilities of the non-AP MLD 60 to the AP1 20, as shown in Fig. 7 by a corresponding notification 321 , or the AP1 20 extracts this information from the association request 311 .
  • the CE 10 is aware of the AP capabilities to be included in the association response 313.
  • the CE 10 is the counterpart for the non-AP MLD 60 meaning that every time a MAC address is needed in an authentication, encryption, and security mechanism, which is the MAC address of the CE 10.
  • the CE 10 After association the CE 10 causes the DS 10 to provide or change the mapping to AP1 20, e.g. by transmitting a corresponding notification or instruction 320.
  • Fig. 8 shows a diagram of another embodiment of an association operation according to the present disclosure.
  • the association in the association operation 310’ happens between non-AP MLD 60 and AP1 20, after which AP1 20 informs the CE 10 of parameters required from the association and the success state through a corresponding notification 315. All other steps are generally unchanged.
  • an 802.1X authentication 330 and/or a 4-way handshake operation 340 are optionally performed. Both are done between the non-AP MLD 60 and the CE 10.
  • the 802.1X authentication 330 may be used to verify the non-AP MLD’s identity.
  • the protocol may involve multiple frame exchanges and the CE 10 may consult an external entity for authentication of the non-AP MLD 60.
  • the CE 10 instructs AP1 20 by notification 331 to switch “802.1X controlled and uncontrolled port filtering”, as e.g. shown in Figs. 3 to 6, from “uncontrolled” (U) to “controlled” (C).
  • the “4-way handshake” 340 may be used to establish an encrypted link between non-AP MLD 60 and the CE 10 for use between the non-AP MLD 60 and one or more APs 20, 30.
  • the protocol may involve multiple frame exchanges between non-AP MLD 60 and CE 10 with AP1 20 forwarding respective frames accordingly.
  • the non-AP MLD 60 and the CE 10 may derive (steps 341 , 342) the same “temporal keys” for unicast data frames (PTK) and groupcast data frame (GTK).
  • the CE 10 shares these keys PTK and GTK with the AP1 20 by a corresponding notification 343 via a secure link such that the AP1 20 can communicate with the non-AP MLD 60 in an encrypted fashion.
  • labels indicating the state (“state 1” to “state 4”) show in which state the link 101 between AP1 20 and non-AP MLD 60 is.
  • Different frames are allowed to be transmitted in each state as defined in the IEEE 802.11 standard (e.g., (user) data frames are only allowed to be transmitted in state 4).
  • Successful operation in a previous state causes transition to the next state.
  • a state may be skipped (e.g. transition from state 2 to state 4 may be provided).
  • Fig. 9 shows a diagram of an embodiment of data transfer operation 350 according to the present disclosure.
  • MSDUs data units
  • the CE 10 is generally not involved in any data transfer. Regular operation is applied for accessing the channel, e.g., Enhanced Distributed Channel Access (EDCA) and/or trigger-based access.
  • EDCA Enhanced Distributed Channel Access
  • Fig. 10 shows a diagram of an embodiment of an on-boarding operation 360 according to the present disclosure. Before a new link (link 2 102) to a new AP (AP2 30) is to be enabled, the new AP needs to be on-boarded by the CE 10. Generally, every link is first enabled and then activated.
  • Enable means that after the enabling procedure, the link may be used for non-(user) data frames.
  • Activate means that after the activate procedure, the link may be used for (user) data frames, too.
  • a formerly enabled link may be re-activated without a new enabling procedure. “Adding” a new link thus generally involves on-board- ing/enabling and activating of the link.
  • the non-AP MLD 60 triggers the addition by transmitting a frame 361 to AP1 20 which is forwarded (362) to the CE 10.
  • the non-AP MLD 60 may have gotten notice from AP2 by API’s neighbor report or by reception of AP2’s beacon.
  • the AP1 20 and/or the CE 10 triggers the on-boarding of AP2 30 in which case the first (step 361) and/or the second frames (step 362) from the non-AP MLD 60 to the AP1 20 are dropped in the operation shown in Fig. 10.
  • the CE 10 transmits, as the on-boarding procedure, a first level of context information (“first context information”) 363 to AP2 30, comprising one or more of the STA’s capabilities, PTK and GTK. Further, the CE 10 instructs the AP2 30 by a notification 364 to switch to “controlled port” if 802.1X authentication is enabled. Agreements (BAck, TWT) may be included, if the CE 10 is aware of them.
  • the CE 10 instructs the AP2 30 by instruction 365 to enable link 2 for the particular non-AP MLD 60 and informs non-AP MLD 60 by notification 366, 367 via AP1 that link 2 is enabled.
  • AP2 capabilities are shared with the non-AP MLD 60.
  • AP1 20 may transmit the “new link enabled” frame 367 as part of a beacon frame or a link reconfiguration notify frame.
  • Fig. 11 shows a diagram of an embodiment of an activation operation 370 according to the present disclosure.
  • the non-AP MLD 60 may decide to activate the new link (link 2) by transmitting an “activate new link” frame 371 to AP1 20, for instance because link 2 may have higher received power than link 1.
  • the “activated new link” frame 37 may be a “link reconfiguration request” frame.
  • AP1 20 and/or CE 10 may decide to activate link 2, in which case the “activate new link” is internally generated and/or transmitted from CE 10 to AP1 20, respectively.
  • the AP1 20 in turn conveys the second level of context information (“second context information”) 372 to the AP2 30, comprising one or more of Packet number (PN) and sequence number (SN), Agreements (BAck, TWT) and PTK/ GTK, if not conveyed earlier.
  • second context information e.g. a confirmation may be transmitted from AP2 30 to AP1 20; not shown
  • the AP1 20 informs the CE 10 by message 373 that context has been transferred to the AP2 30.
  • the context is transferred directly from AP1 20 to AP2 30, but it may also go from AP1 20 to AP2 30 via the CE 10.
  • the CE 10 subsequently changes the mapping of the DS 70 such that data units to/from the non- AP MLD 60 can now be delivered via the AP2 by notification 374. Subsequently, the CE 10 informs the AP1 20 and the non-AP MLD 60 that link 2 is activated.
  • the “new link activated” frame 375, 376 may be a “link reconfiguration response” frame.
  • new data units e.g. MSDUs
  • the non-AP MLD 60 is informed about the new link being activated, new MSDUs from the non-AP MLD 60 to the DS 70 are transmitted via the AP2 30 and link 2 (not shown in Fig. 11).
  • the old link 1 can be deactivated if needed via a frame exchange “deactivate old link” 377, 378. While link 1 is activated, the AP1 20 can still serve buffered downlink (from AP to non-AP) data to non-AP MLD 60 via link 1. However, no new data and no uplink (from non-AP to AP) data can generally be exchanged because non-AP MLD 60 has no mapping to the DS 70 via the AP1 20 anymore.
  • the first context information substantially contains static or rather static information meaning that this information changes rarely if at all.
  • the second context information contains highly dynamic information such as sequence number (SN) or packet number (PN). Those counters generally increase monotonically.
  • SN sequence number
  • PN packet number
  • the AP1 20 After the AP1 20 has assigned SN and PN to its last packets to be transmitted, it forwards this second context information to the AP2 30 for further use. For example, assuming APTs last SN is #100, then AP2 uses as a first SN #101 or greater. The second context information would then be either #100 or #101.
  • Fig. 12 shows a diagram illustrating an exemplary data flow during the roaming procedure. Initially, after the CE 10 instructs the DS 70 to map the non-AP MLD 60 to the AP1 20, downlink (DL) MSDUs 401 and uplink (UL) MSDUs 402 are exchanged via link 1.
  • DL downlink
  • UL uplink
  • buffered DL MSDUs 403 at the AP1 20 can still be transmitted via link 1 to the non-AP MLD 60 until link 1 gets deactivated and as long as the context information does not need to be modified. Therefore, transmission of buffered DL MSDUs 403 via link 1 may only work when SN and PN have been already assigned before the context was transferred to the AP2 30 and MSDUs are received with increasing PN order. Otherwise, buffered DL MSDUs 403 may be discarded or forwarded to the AP2 30 as explained below.
  • the DL data service to the non-AP MLD 60 may be interrupted starting from the point in time, when the AP1 20 transfers the context to the AP2 30 until the DS mapping changed.
  • Fig. 13 shows a diagram of another embodiment of an activation operation 370’ according to the present disclosure.
  • those buffered data units are conveyed to the AP2 30 together with the context information 372’ according to this embodiment.
  • Such an operation may be done TID-wise (traffic identifier) for, e.g., high priority MSDUs.
  • deactivation of link 1 is TID specific.
  • the new link may be activated together with the old link being deactivated by a corresponding notification 375’, 376’.
  • a separate “deactivate old link” notification (377 in Fig. 11) may be transmitted later for the TIDs that are still active on link 1.
  • Fig. 14 shows a diagram illustrating buffer flushing in the context of the present disclosure. Since old link and new link share the same SN space, it may happen that old, non-suc- cessfully transmitted MSDUs (indicated as data unit “DU” in Fig. 14) hinder the MSDU output at the MAC SAP of the non-AP MLD. It may be a desired behavior to keep the order of MSDUs at the receiver. In the situation depicted in Fig. 14, the assumption is made that MSDUs with SNs #1 to #5 are transmitted by the AP1 before the roaming, whereas the MSDUs with SN #6 and #7 are transmitted by the AP2 afterwards. Since the MSDU with SN #3 was initially erroneously received, MSDUs with SN #4 to #7 are buffered until SN #3 is successfully retransmitted.
  • FIG. 15-17 show diagrams illustrating different embodiments to resolve this issue of flushing buffer illustrated in Fig. 14. The difference between the different embodiment mainly lies in the entity triggering the flushing buffer process. The assumption underlying the embodiments shown in Figs. 15-17 is that the retransmission is done from the API via link 1. lf AP2 performs the retransmissions (in case the buffered data units have been transferred during context transfer as shown in Fig.
  • a step of “drop MSDUs until lastSN” is performed at AP2 after the predetermined duration. This requires that the predetermined duration is known to AP2; hence it is transferred together with the buffered data units during context transfer as shown in Fig. 13. Retransmission by AP2 implies that no timer is required at AP1.
  • Fig. 15 shows a diagram of a first embodiment of dealing with flushing buffer operation that is AP1 driven.
  • a predetermined du- ration 403 is computed based on MSDU lifetime and/or maximum number of retransmissions.
  • a BAck request (BAR) frame 404 is transmitted identifying the new sequence number which is the first SN to be used by the AP2 30 which may be lastSN+1 or higher.
  • the predetermined duration may be different for MSDUs in which case the lastSN contained in the BAR refers to an SN ⁇ lastSN with SN being the largest SN of the MSDU that exceeded the duration. In such a case multiple BARs may be sent.
  • a BAR causes the received buffer of the non-AP LD 60 to be emptied in order, regardless of any non-received MSDUs, until the indicated SN-1.
  • the step 405 of “drop MSDUs until lastSN” is performed at the AP1 after the predetermined duration. Flushing buffer by AP1 may have the drawback that the old link 1 deteriorated too much for the non-AP MLD to receive the BAR successfully.
  • Fig. 16 shows a diagram of a second embodiment of dealing with flushing buffer that is AP2 30 driven.
  • the AP1 20 shares the predetermined duration with the AP2 30.
  • the AP2 30 may transmit a data unit with an SN larger than lastSN + BAck window size used in step 407.
  • lastSN needs to be signaled to AP2 e.g., in the “new link activated” frame 402’. Flushing buffer by AP2 has the advantage that the new link is tentative more stable than the old link and therefore reception of BAR by the non-AP MLD is more likely.
  • Fig. 17 shows a diagram of a third embodiment of dealing with flushing buffer that is non- AP MLD 60 driven.
  • AP1 drops (step 405) all buffered MSDUs until lastSN and ceases any transmission attempt after the predetermined duration passed.
  • FIG. 18 and 19 show diagrams illustrating different embodiments to resolve this issue of flushing buffer in UL.
  • the non-AP MLD 60 finishes all MSDU transmissions in UL before initiating the activation of link 2.
  • the non-AP MLD 60 transmits at least all buffered MSDUs 502 that hinder MSDUs indicated as successfully received to be forwarded to higher layer at the AP1 20. Retransmissions of those MSDUs are done until successfully received (confirmed via BAck) and/or until the MSDU lifetime ended.
  • a BAR 503 may be sent to the AP1 20. If retransmissions are not successful, a BAR is be sent to the AP1 20 as well. Subsequently, link 2 can be activated in step 504 and context transfer 505 starts.
  • the AP1 requests (step 513) transmission of remaining MSDUs that hinder MSDUs in received buffer to be output at its MAC SAP. Subsequently, the non-AP MLD 60 sends the requested MSDU(s) 514 to the AP2 30 in one or more frame exchanges until received successfully. If the number of retransmissions is achieved or lifetime ended, the non-AP MLD 60 sends a BAR (not shown in Fig. 19) such that all buffered and successfully received MSDUs at the AP1 20 can be output at its MAC SAP.
  • Fig. 20 shows a flow chart of an embodiment of a control method 600 of a control device (e.g. the control entity 10).
  • the control method is configured for controlling the routing of data units between the DS 70 and one of two or more APs 20, 30, each being configured to communicate with the MLD 60 via a separate link.
  • the control device receives a request from the MLD or the first AP to add a second link between the LD and a second AP (e.g. AP2) while a first link between the MLD and a first AP (e.g. AP1) is enabled.
  • a second AP e.g. AP2
  • a first link between the MLD and a first AP e.g. AP1
  • control device transmits, to the second AP, first context information configured for use by the second AP to communicate with the MLD.
  • the control device adds, in particular activates, the second link and notifies the MLD of the addition of the second link.
  • Fig. 21 shows a flow chart of an embodiment of a first communication method 700 of a non-AP MLD 60 for communicating with one or more access points (APs) via separate links.
  • the MLD transmits a request to the control device to add a second link between the MLD and the second AP while a first link between the MLD and the first AP is enabled.
  • the MLD receives a notification from the control device or the second AP regarding the addition of the second link.
  • Fig. 22 shows a flow chart of an embodiment of a second communication method 800 of an access point (e.g. AP1 20 or the AP2 30) for communicating with the MLD via a first link.
  • the AP receives a request from the MLD or generates such a request to add a second link between the MLD and a second AP while a first link between the MLD and a first AP is enabled.
  • the AP transmits the request to the control device.
  • the AP receives a notification from the control device and/or the second AP regarding the addition of the second link.
  • the AP transmits the notification to the MLD.
  • devices and method are presented that are configured to leverage multi-link operation which can provide almost seamless roaming.
  • the control entity is provided separately from a particular AP to which a STA associates once.
  • the control entity provides the necessary information to the new serving AP and the formerly serving AP transfers a minimum of information to the newly serving AP.
  • the control entity controls the distribution system such that the STA is served via the new AP.
  • the device may be implemented by respective units or circuitry, e.g. a processor, processing circuitry, a computer, dedicated hardware, etc., that carries out the functions of the device.
  • a common unit or circuitry e.g. a common processor or computer, may implement the various functions of the device, or separate units or elements may be used that together represent the circuitry.
  • a circuit is a structural assemblage of electronic components including conventional circuit elements, integrated circuits including application specific integrated circuits, standard integrated circuits, application specific standard products, and field programmable gate arrays. Further, a circuit includes central processing units, graphics processing units, and microprocessors which are programmed or configured according to software code. A circuit does not include pure software, although a circuit includes the above-described hardware executing software. A circuit or circuitry may be implemented by a single device or unit or multiple devices or units, or chipset(s), or processor(s).
  • Control device configured to control the routing of data units between a distribution system and one of two or more access points (APs), each being configured to communicate with a multi-link device (MLD) via a separate link
  • the control device comprising circuitry configured to: receive a request from the MLD or the first AP to add a second link between the LD and a second AP while a first link between the MLD and a first AP is enabled; transmit, to the second AP, first context information configured for use by the second AP to communicate with the MLD; and add the second link and notify the MLD of the addition of the second link.
  • Control device configured to receive the request from the MLD via the first AP and the first link or from the first AP and/or to notify the MLD of the addition of the second link via the first AP and the first link.
  • adding the second link includes transmitting an enablement instruction to the second AP instructing the second AP to enable the second link between the second AP and the MLD. 4. Control device according to embodiment 3, wherein adding the second link further includes transmitting an activation notification to the MLD after the second link was enabled to notify the MLD of the addition of the second link.
  • Control device wherein the circuitry is configured to transmit the enablement notification and/or the activation notification to the MLD via the first AP and the first link.
  • Control device configured to activate the second link in response to reception of a context notification from the first AP informing the control device that second context information configured for use by the second AP to communicate with the MLD has been transmitted from the first AP to the second AP or in response to reception of a notification from the second AP that second context information configured for use by the second AP to communicate with the MLD has been received from the first AP.
  • Control device configured to control the distribution system to change the routing from first AP to second AP for said MLD before transmitting the activation notification to the MLD or before the second link is activated.
  • circuitry is configured, during and/or after an association between the first AP and the MLD, to obtain the first context information from the first AP or the MLD and/or to determine the first context information from an association request received from the first AP.
  • the first context information includes one or more of: encryption keys for encrypting and decrypting data units; association and/or capability information of the first and/or second AP and/or the MLD; and agreements with respect to data communication.
  • Control device according to embodiment 8 or 9, wherein the circuitry is configured to perform an authentication and/or handshake process with the MLD after or as part of the association.
  • control device is arranged in the same network as the two or more APs and is connected directly to the respective AP or to control circuitry of the respective AP.
  • Multi-link device configured to communicate with one or more access points (APs) via separate links, the MLD comprising circuitry configured to: transmit a request to a control device to add a second link between the MLD and a second AP while a first link between the MLD and a first AP is enabled; and receive a notification from the control device or the second AP regarding the addition of the second link.
  • MLD according to embodiment 12, wherein the circuitry is configured to transmit the request to the control device via the first AP and the first link and/or to receive the notification from the control device regarding the addition of the second link via the first AP and the first link and/or from the second AP via the second link.
  • MLD according to any one of embodiments 12 to 13, wherein the circuitry is configured to perform an association with the control device via the first AP and the first link to obtain and/or determine first context information configured for use by the first AP and/or the second AP to communicate with the MLD.
  • MLD according to any one of embodiments 12 to 14, wherein the circuitry is configured to receive, as notification regarding the addition of the second link, an enablement notification from the control device and/or the second AP informing the MLD that the second link has been enabled; transmit an activation request to the first AP regarding the activation of the second link; and receive an activation notification from the control device informing the MLD that the second link has been activated.
  • MLD according to any one of embodiments 12 to 15, wherein the circuitry is configured to transmit a deactivation request to the first AP regarding the deactivation of the first link; and receive a deactivation notification from the first AP informing the MLD that the first link has been deactivated.
  • MLD according to any one of embodiments 12 to 16, wherein the circuitry is configured, after enablement of the second link or after an intention to activate the second link, to transmit buffered data units to the first AP via the first link for a predetermined duration or until the lifetime of the data units ended.
  • Access point (AP1) configured to communicate with a multi-link device (MLD) via a first link, the MLD being configured to communicate with one or more access points via separate links and to communicate with a control device, the AP comprising circuitry configured to: receive a request from the MLD or generate a request to add a second link between the MLD and a second AP while a first link between the MLD and a first AP is enabled; transmit the request to the control device; and receive a notification from the control device and/or the second AP regarding the addition of the second link; and transmit the notification to the MLD.
  • MLD multi-link device
  • AP configured to transmit second context information directly to the second AP or via the control device after the second link has been enabled, the second context information being configured for use by the second AP to communicate with the MLD.
  • the second context information includes one or more of a current packet number (PN) and/or a current sequence number (SN) of a data unit; a reset indication of the PN and/or the SN; acknowledgement information regarding the data communication; and buffer information.
  • PN current packet number
  • SN current sequence number
  • circuitry is configured to transmit the second context information in response to an activation request from the MLD; receive an activation notification regarding the activation of the second link from the control unit or the first AP; and transmit the activation notification to the MLD.
  • circuitry is configured to receive a deactivation request from the MLD requesting the deactivation of the first link; deactivate the first link; and transmit a deactivation notification to the MLD informing the MLD that the first link has been deactivated.
  • circuitry is configured to determine the first and/or second context information from an association request received from the MLD.
  • circuitry is configured, after activation of the second link, to transmit data units buffered within the AP either to the MLD via the first link until the first link is deactivated or to the second AP along with the transmission of the second context information.
  • circuitry is configured, after an activation request is received from the MLD, to retrieve data units from the MLD by transmitting a transmission request to the MLD, said transmission request requesting the MLD to transmit data units to the AP, in particular data units complementing the receive buffer of the AP.
  • Control method of controlling the routing of data units between a distribution system and one of two or more access points (APs), each being configured to communicate with a multi-link device (MLD) via a separate link comprising: receiving a request from the MLD or the first AP to add a second link between the MLD and a second AP while a first link between the MLD and a first AP is enabled; transmitting, to the second AP, first context information configured for use by the second AP to communicate with the MLD; and adding the second link and notify the MLD of the addition of the second link.
  • MLD multi-link device
  • Communication method of communicating with one or more access points (APs) via separate links comprising: transmit a request to a control device to add a second link between a multi-link device (MLD) and a second AP while a first link between the MLD and a first AP is enabled; and receive a notification from the control device or the second AP regarding the addition of the second link.
  • MLD multi-link device
  • Communication method of communicating with a multi-link device (MLD) via a first link the MLD being configured to communicate with one or more access points (APs) via separate links and to communicate with a control device, the communication method comprising: receiving a request from the MLD or generate a request to add a second link between the MLD and a second AP while a first link between the MLD and a first AP is enabled; transmitting the request to the control device; and receiving a notification from the control device and/or the second AP regarding the addition of the second link; and transmitting the notification to the MLD.
  • MLD multi-link device
  • APs access points
  • a non-transitory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the method according to embodiment 27, 28, 29 or 33 to be performed.
  • a computer program comprising program code means for causing a computer to perform the steps of said method according to embodiment 27, 28, 29 or 33 when said computer program is carried out on a computer.
  • Access point configured to communicate with a multi-link device (MLD) via a second link
  • the MLD being configured to communicate with one or more access points via separate links and to communicate with a control device
  • the AP comprising circuitry configured to receive a request from the control device to enable a second link between the MLD and the AP while a first link between the MLD and a first AP is enabled; enable the second link; and transmit a notification regarding the addition of the second link to the MLD via the second link or to the control device.
  • Communication method of communicating with a multi-link device (MLD) via a second link the LD being configured to communicate with one or more access points via separate links and to communicate with a control device, the communication method comprising receiving a request from the control device to enable a second link between the MLD and the AP while a first link between the MLD and a first AP is enabled; enabling the second link; and transmitting a notification regarding the addition of the second link to the MLD via the second link or to the control device.
  • MLD multi-link device

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Computer Security & Cryptography (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Dispositif de commande conçu pour commander le routage d'unités de données entre un système de distribution et l'un d'au moins deux points d'accès (AP), chacun étant conçu pour communiquer avec un dispositif à liaisons multiples (MLD) par l'intermédiaire d'une liaison séparée, le dispositif de commande comprenant des circuits conçus pour recevoir une demande provenant du MLD ou du premier AP pour ajouter une seconde liaison entre le MLD et un second AP tandis qu'une première liaison entre le MLD et un premier AP est validée ; pour transmettre, au second AP, des premières informations de contexte conçues pour être utilisées par le second AP pour communiquer avec le MLD ; et pour ajouter la seconde liaison et notifier le MLD de l'ajout de la seconde liaison.
PCT/EP2025/062274 2024-05-10 2025-05-06 Dispositif de commande, dispositif à liaisons multiples, point d'accès et procédés Pending WO2025233307A1 (fr)

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Application Number Priority Date Filing Date Title
EP24175160 2024-05-10
EP24175160.1 2024-05-10

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20240114415A1 (en) * 2022-09-27 2024-04-04 Qualcomm Incorporated Wireless local area network make-before-break handover

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20240114415A1 (en) * 2022-09-27 2024-04-04 Qualcomm Incorporated Wireless local area network make-before-break handover

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
BINITA GUPTA (CISCO SYSTEMS): "Seamless roaming within a mobility domain - follow up", vol. 802.11 UHR; 802.11bn, 26 March 2024 (2024-03-26), pages 1 - 18, XP068276413, Retrieved from the Internet <URL:https://mentor.ieee.org/802.11/dcn/24/11-24-0396-00-00bn-seamless-roaming-within-a-mobility-domain-follow-up.pptx> [retrieved on 20240326] *
BINITA GUPTA (CISCO SYSTEMS): "Seamless roaming within a mobility domain", vol. 802.11 UHR; 802.11bn, no. 1, 17 January 2024 (2024-01-17), pages 1 - 26, XP068275222, Retrieved from the Internet <URL:https://mentor.ieee.org/802.11/dcn/23/11-23-2157-01-00bn-seamless-roaming-within-a-mobility-domain.pptx> [retrieved on 20240117] *

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