WO2022157239A1

WO2022157239A1 - Device and method for multi-link transmissions

Info

Publication number: WO2022157239A1
Application number: PCT/EP2022/051221
Authority: WO
Inventors: Stephen Mccann; Michael Montemurro
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2021-01-20
Filing date: 2022-01-20
Publication date: 2022-07-28
Also published as: EP4278705A1; CN116762466A

Abstract

The present disclosure relates to multi-link transmission in wireless communications. To this end, the disclosure proposes a wireless device for transmitting multi-link, ML, configuration, wherein the wireless device corresponds to one or more affiliated APs, the wireless device being configured to: obtain, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether the one or more affiliated APs is operating a legacy BSS; transmit, by the wireless device, the ML configuration within a subfield of an ML element.

Description

DEVICE AND METHOD FOR MULTI-LINK TRANSMISSIONS

TECHNICAL FIELD

The present disclosure relates generally to wireless communications, and more particularly to multi-link transmissions.

BACKGROUND

A wireless communications system to which the embodiments of this disclosure are applicable may be a wireless local area network (wireless local area network, WLAN) system or a cellular network system. A group addressed service transmission method, which transmits broadcast and multicast frames, may be implemented by a communications device in the wireless communications system, or a chip or a processor in the communications device. The communications device may be a wireless communications device that supports parallel transmission on a plurality of links. For example, it is called a multi-link device or a multi-band device. Multi-link devices have higher transmission efficiency and higher throughput than devices that support only single-link transmission.

The Extremely High Throughput (EHT) Task Group (TG) has recently started standardization activities within the IEEE 802.11 WLAN project and this TG is known as 802.1 Ibe. One of the new fundamental features is the creation of a Multi-Link Device (MLD). This is described as a WLAN entity that has multiple radio links to another MLD or another MLD entity.

Although the latest draft from P802.1 Ibe describes some basic requirements for MLD operation, it does not cover how group addressed frames are delivered.

SUMMARY

In view of the above-mentioned limitations, embodiments of the present disclosure aim to introduce a solution for multi-link transmissions. In particular, an objective is to prevent the unnecessary replication of Group Addressed Frames.

The objective is achieved by embodiments as provided in the enclosed independent claims. Advantageous implementations of the embodiments are further defined in the dependent claims. A first aspect of the disclosure provides a wireless device for transmitting multi-link, ML, configuration, wherein the wireless device corresponds to one or more affiliated APs, the wireless device being configured to: obtain, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether the one or more affiliated APs is operating a legacy BSS; and transmit, by the wireless device, the ML configuration within a subfield of an ML element.

New functionality provided by the present disclosure within the wireless device (for example, AP MLD) that prevents the unnecessary replication of Group Addressed Frames. This functionality operates depending on whether traffic is routed from a backhaul LAN connection through to legacy STAs that are attached to the AP MLD.

Embodiments of this disclosure propose a wireless device for multi-link transmission that can operate accordingly as described in first aspect and its implementation forms.

In an implementation form of the first aspect, the ML configuration is further indicative of whether the legacy BSS of the one or more affiliated APs is in the same ESS as the BSS of the wireless device or in a different ESS from that of the BSS of the wireless device.

In an implementation form of the first aspect, a first value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device; a second value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in a different ESS from that of the wireless device; and/or a third value of the subfield is indicative of the one or more affiliated APs is not operating a legacy BSS.

In an implementation form of the first aspect, the wireless device is further configured to suppress the transmission of group addressed frames when one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device.

In an implementation form of the first aspect, the wireless device is further configured to transmit a group key based on the value of the subfield. New functionality provided by the present disclosure within the non-AP MLD to determine which keys (e.g. GTK, IGTK) are negotiated based on the configuration of the AP MLD and the affiliated APs, when the configuration information is received from the AP MLD.

The wireless device of the present disclosure provide a way to save radio resources and the possible prevention of unnecessary transmission and reception of duplicated Group Addressed frames in an AP MLD and non-AP MLD.

A second aspect of the disclosure provides a wireless device for receiving multi-link, ML, configuration, wherein the wireless device corresponds to one or more affiliated STAs, the wireless device being configured to: receive, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether one or more affiliated APs is operating a legacy BSS, wherein the ML configuration is carried on a subfield of an ML element; and perform, by the wireless device, interaction with another wireless device based on the ML configuration.

In an implementation form of the second aspect, the ML configuration is further indicative of whether the legacy BSS of the one or more affiliated APs is in the same ESS as the BSS of the wireless device or in a different ESS from that of the BSS of the wireless device.

In an implementation form of the second aspect, a first value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device; a second value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in a different ESS from that of the wireless device; and/or a third value of the subfield is indicative of the one or more affiliated APs is not operating a legacy BSS.

A third aspect of the disclosure provides a method for transmitting multi-link, ML, configuration performed by a wireless device, wherein the wireless device corresponds to one or more affiliated APs, the method comprising: obtaining, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether the one or more affiliated APs is operating a legacy BSS; and transmitting, by the wireless device, the ML configuration within a subfield of an ML element. Implementation forms of the method of the third aspect may correspond to the implementation forms of the wireless device of the first aspect described above. The method of the third aspect and its implementation forms achieve the same advantages and effects as described above for the wireless device of the first aspect and its implementation forms.

A fourth aspect of the disclosure provides a method for receiving multi-link, ML, configuration performed by a wireless device, wherein the wireless device corresponds to one or more affiliated STAs, the method comprising: receiving, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether the one or more affiliated APs is operating a legacy BSS, wherein the ML configuration is carried on a subfield of an ML element; and performing, by the wireless device, interaction with other wireless devices based on the ML configuration.

Implementation forms of the method of the fourth aspect may correspond to the implementation forms of the wireless device of the second aspect described above. The method of the fourth aspect and its implementation forms achieve the same advantages and effects as described above for the wireless device of the second aspect and its implementation forms.

A fifth aspect of the disclosure provides a computer program product comprising a program code for carrying out, when implemented on a processor, the method according to the third aspect and any implementation forms of the third aspect, or the fourth aspect and any implementation forms of the fourth aspect.

A sixth aspect of the disclosure provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is run on a computer, the computer is enabled to perform the method according to any one of the third aspect and any implementation forms of the third aspect, or the fourth aspect and any implementation forms of the fourth aspect.

A seventh aspect of the disclosure provides a chip system, comprising a processor, configured to invoke a computer program from a memory and run the computer program, so that a communications device on which the chip system is installed performs the method according to any one of the third aspect and any implementation forms of the third aspect, or the fourth aspect and any implementation forms of the fourth aspect. It has to be noted that all devices, elements, units and means described in the present disclosure could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present disclosure as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS

The above described aspects and implementation forms of the present disclosure will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

Figure la shows a Multi-Link Device (MLD) Architecture.

Figure lb shows an example of the establishment of a 3 link connection between an AP MLD and a non-AP MLD.

Figure 2 shows a simplified authentication protocol to establish a secure connection between a non-AP STA and an AP.

Figure 3 shows another example of an MLD configuration.

Figure 4 shows scenario 1 for MLD behavior.

Figure 5 shows group addressed frames that are transmitted by the AP MLD.

Figure 6 shows scenario 2 for MLD behavior.

Figure 7 shows group addressed frames that are transmitted by the AP MLD.

Figure 8 shows another manner of transmission of group addressed frames.

Figure 9 shows scenario 3 for MLD behavior.

Figure 10 shows group addressed frames that are transmitted by the AP MLD.

Figure 11 shows a method for multi-link transmission.

Figure 12a shows the format of the new Group Addressed Configuration subfield in the ML element frame.

Figure 12b shows the breakdown of the GA Configuration field within an ML element. Figure 13 shows a wireless device 500 according to an embodiment of the disclosure.

Figure 14 shows a schematic structural diagram of a multi-link device according to an embodiment of this disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Illustrative embodiments of methods, devices, and program product for ML transmissions in a communication system are described with reference to the figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the disclosure.

Moreover, an embodiment/example may refer to other embodiments/examples. For example, any description including but not limited to terminology, element, process, explanation and/or technical advantage mentioned in one embodiment/example is applicative to the other embodiments/examples.

Figure la shows a Multi-Link Device (MLD) Architecture. An AP MLD includes one or more affiliated APs. A STA MLD includes one or more affiliated STAs.

In WLAN, a typical case would be an Access Point (AP) MLD connecting to a non-AP MLD (or a WLAN terminal) using 2 radio links in the 2.4 GHz and 5 GHz WLAN bands. The individual radio links are referred to as links. The radio function entities within the AP MLD are referred to as affiliated APs. And the AP MLD and non-AP MLD form a BSS which has a SSID, e g., SSIDx.

It is also intended that each of the affiliated APs can also serve legacy non-AP STAs. For example, an AP MLD with a 2.4 GHz radio link could also behave as a legacy AP serving a legacy 802.1 lax non-AP STA. In this case, the function entity of implementing the 2.4 GHz radio link is the affiliated AP within the AP MLD. A function entity of implementing the 5 GHz (or 6 GHz or another frequency) radio link is also an affiliated AP within the AP MLD.

The operation of an MLD is different from that of two logical STAs in the same physical entity (e.g. two non-AP STAs in the same handset). Within an MLD the traffic is coordinated between the two links and the security association is maintained across them. This provides some benefits over the virtual STA concept. For ease of description, in this disclosure, a multi-link device that is an AP (a new kind of AP defined, for example, in 802.1 Ibe) may be referred to as a multi-link AP, a multi-link AP device, or an AP multi-link device (AP multi-link device, AP MLD). A multi-link device that belongs to a non-AP STA may be referred to as a multi-link STA, a multi-link STA device, or a STA multi-link device (STA multi-link device, STA MLD). For ease of description, "the multi-link device includes a member STA" is also briefly described as "the multi-link device includes a STA" in this embodiment of this disclosure.

For example, the multi-link device in this document may be a single-antenna device, or may be a multi-antenna device. For example, a device with more than two antennas may be used. A quantity of antennas included in the multi-link device is not limited in this embodiment of this disclosure. In this embodiment of this disclosure, the multi-link device may allow network traffic for the same network to be transmitted on different links, or even allow a same data packet to be transmitted on different links. Alternatively, network traffic for the same network cannot be transmitted on different links, but network traffic for different networks can be transmitted on different links.

In this example, AP MLD has three affiliated APs. AP 1 operates on 2.4 GHz band, AP 2 operates on 5 GHz band, and AP 3 operates on 6 GHz band. The non-AP STA 1 affiliated with the non-AP MLD sends an Association Request frame to AP 1 affiliated with the AP MLD, i.e., the Transmitter Address (TA) of the Association Request frame is set to the MAC address of the non-AP STA 1 and the Receiver Address (RA) of the Association Request frame is set to the MAC address of the AP 1. The Association Request frame includes complete information of non-AP STA 1, non-AP STA 2, and non-AP STA 3 to request three links to be setup (one link between AP 1 and non-AP STA 1, one link between AP 2 and non-AP STA 2, and one link between AP 3 and non-AP STA 3) and an ML element that indicates the MLD MAC address of the non-AP MLD. The AP 1 affiliated with the AP MLD sends an Association Response frame to non-AP STA 1 affiliated with the non-AP MLD, i.e., the TA of the Association Response frame is set to the MAC address of the AP 1 and the RA of the Association Response frame is set to the MAC address of the non-AP STA 1, to indicate successful multi-link setup. Figure 2 shows a simplified authentication protocol to establish a secure connection between a non-AP STA and an AP. The procedure shown in Figure 2 is referred to 4-way handshake. It is used to establish a secure connection between a non-AP STA and an AP.

In the procedure, the AP and non-AP STA exchange 4 messages to derive keying material and establish a security association. For an infrastructure connection, the first message is transmitted from the AP to the non-AP STA and contains a random number generated by the AP, referred to as an Authenticator Nonce (ANonce). The non-AP STA receives and validates the first message, generates a random number, referred to as a Supplicant Nonce (SNonce), calculates a Message Integrity Code (MIC) over the contents of the second message, and transmits the second message to the AP. The AP receives and validates the second message; completes derivation of encryption keys and transmits the third message to the non-AP STA. The non-AP STA receives and validates the third message and transmits the fourth message to the AP to acknowledge that the 4-way handshake has been successfully completed. These messages are used to exchange security information. The objective of the 4-way handshake is to create security keys (e.g. a Group Temporal Key (GTK) and an Integrity Group Temporal Key (IGTK) together with other keys that are not shown) between the AP (authenticator) and a non-AP STA (supplicant). These keys are subsequently used to encrypt data between the AP and STA. The GTK, IGTK are carried within Key Data Elements (KDEs) and IEEE 802.11 defines many types of KDEs for various keys, of which the GTK, IGTK are two keys.

The content of the 4-way handshake messages and the algorithms used to derive keying material are negotiated between the AP and non-AP STA prior to the 4-way handshake during 802.11 association (i.e. through the exchange of Association Request and Association request/response). Status codes are not used within the 4-way handshake, therefore both the AP and the non-AP STA need to know how the subfields are encoded, before the 4-way handshake commences, so they do not incorrectly de-code each message of the sequence.

Another procedure referred to Group Key handshake is also used in security association. A group key handshake is a simplified two message exchange used to re-new group keys (e.g. GTK, IGTK) when the original group keys need to be refreshed. The Group Key handshake is initiated by the AP to each associated STA and only occurs following a successful 4-way handshake. Figure 3 shows another example of an MLD configuration. In this example, the deployment uses a single hardware. The AP MLD supports 2 radios operating in the 2.4 GHz band and 5 GHz band, an MLD configuration and/or legacy STA connectivity. Moreover, the AP MLD may support for the operation of multiple BSSs on the same radio (using same physical hardware, under different packet protocols) (e.g. one link of a home network (BSS1 : AP MLD and non-AP MLD) and a guest legacy network (BSS2: 2.4 GHz AP and Legacy STA1) on the same radio).

Although Figure 3 only shows a single ESS that is configured so that the BSSs, which are advertised by the AP MLD, the 2.4 GHz affiliated AP and the 5 GHz affiliated AP respectively, all advertise the same ESS using the same SSID, for example, SSIDx.

Both affiliated APs transmit identifiers for an MLD BSS and also a legacy BSS. This will likely be done using the Multi-Link element and possibly a modified a multi-BSS element if multiple BSSs are supported by the affiliated APs and AP MLDs. Each of the affiliated APs uses a unique MAC address that would be different from the MLD MAC address.

Legacy STAs associate to either the 2.4 GHz AP (an affiliated AP) or 5 GHz AP (another affiliated AP). The non-AP MLD associates to the AP MLD on separated BSSs.

To the wired G/W (Gateway) on the LAN (Local Area Network), each affiliated AP appears logically as a separate portal (each bridge traffic to LAN independently) and therefore they can be a single physical LAN port. The BSSID for the 2.4 GHz affiliated AP, 5 GHz affiliated AP, and AP MLD all need to be distinct. Otherwise, legacy STAs will encounter problems.

MLD Association

The non-AP MLD is assigned a single MAC address and associates to the AP MLD with its non-AP MLD MAC address. The affiliated STAs of the non-AP MLD associated to the respective affiliated APs of the AP MLD.

This is similar to how a multiband client operates today - one MAC address for different bands. Once associated, this allows a non-AP STA to transition between the 2.4 GHz AP and 5 GHz AP without losing IP connectivity. For a non-AP MLD, this configuration has the further advantage of allowing the non-AP MLD to transition between the AP MLD, the 2.4 GHz AP, and the 5 GHz AP.

MLD BSSID

Since the AP MLD BSSID (“BSSID MLD” in Figure 3) is used in MAC frame addressing, the AP MLD bridges traffic from non-AP MLDs to/from the LAN.

Association for non-AP MLD

The non-AP MLD associates to the AP MLD in the MLD BSS. The non-AP MLD and AP MLD establish a security association (SA) that includes GTK and IGTK.

Regarding Figure 3, The GTK and IGTK are associated with either the BSSID MLD or with each of the BSSID 24 and BSSID 5 depending on the configuration of the AP MLD. Therefore, transmission of the GTK and IGTK for either the MLD or the 2.4 GHz affiliated link and 5 GHz affiliated link may be required for the non-AP MLD also depending on the configuration of the AP MLD.

The GTK and IGTK could also be referred to as (GTK, IGTK)BSSID_MLD, (GTK, IGTK)BSSID_24 and (GTK, IGTK)BSSID 5.

Group Addressed traffic

The AP MLD encrypts traffic using the (GTK, IGTK)BSSID MLD and can send MLD BSS traffic over any link (or duplicate it on all links). The affiliated AP encrypts traffic using the key pair [either (GTK, IGTK)BSSID 24 or (GTK, IGTK)BSSID 5]. Each affiliated STA filters group addressed data traffic, which is not directed to the BSS of the affiliated STA, and receives group addressed management traffic.

When an MLD architecture allows the affiliated AP’s to operate their own BSS concurrently with the MLD BSS, it is possible for group addressed traffic to be replicated. Regarding the MLD architecture in Figure 5 (scenario 2), Group Addressed frames may be duplicated over both radio links (affiliated links) and then again at the MLD link layer, resulting in several copies of the same Group Addressed frame.

However, this is a waste of resources for the radio medium together with the transmitter and receiver power and processing. When an AP MLD and an affiliated AP are operating BSSs in the same ESS, the broadcast/multicast data traffic will be doubled (AP MLD broadcast & affiliated AP broadcast). A legacy STA associated to the affiliated AP will receive group addressed traffic from the affiliated AP.

However, a non-AP MLD will receive duplicated group addressed traffic from both the AP MLD and each affiliated AP. As the non-AP MLD needs to listen to all group addressed frames for management purposes (for example, a spectrum management frame), it will receive and parse all these frames, even when duplicated.

The disclosure is to provide new functionality within the AP MLD that prevents the unnecessary replication of Group Addressed frames. This functionality operates depending on the configuration of the AP MLD and/or whether traffic is routed from a backhaul LAN connection through to legacy STAs that are attached to the AP MLD. Configuration information is advertised to the non-AP MLD.

Within the non-AP MLD new functionality is added to determine which BSS the security keys (for example, GTK, IGTK) are derived from to correctly decrypt the group addressed frames, based on the configuration of the AP MLD. This configuration information is received from the AP MLD.

There are at least three topology scenarios for MLD behavior for group addressed traffic. These are considered below.

Figure 4 shows scenario 1 for MLD behavior. In scenario 1, Affiliated APs are not running a BSS. In this scenario, there is only MLD with no legacy BSS operating.

• The affiliated APs generate beacon frames and probe response frames that contain the AP MLD BSSID and broadcast traffic protected with the AP MLD key pair (GTK, IGTK).

• A new field is added to the multi-link (ML) element that can signal (as one possible configuration option) that a BSS of the AP MLD and a BSS of the affiliated AP (a legacy BSS) are not part of the same BSS. This new field is described below.

• Affiliated APs broadcast beacon frames (need to figure out what beacon contains) to their BSS but do not accept associations. Reply to association requests with as status code of REFUSED, or similar. The BSSID of all group addressed frames is the AP MLD BSSID.

Figure 5 shows group addressed frames that are transmitted by the AP MLD. The affiliated APs (API and AP2) on each link transmit their own beacon frame (shown in red and green) together with a copy of group addressed frames forwarded from the AP MLD, originating on LAN1. The group addressed frames need to be duplicated in this scenario, in case one of the radio links drops between the AP MLD and the non-AP MLD.

Figure 6 shows scenario 2 for MLD behavior. In scenario 2, affiliated APs are operating a BSS that is part of the same ESS as AP MLD. In this scenario shown, there are MLD BSS and two legacy BSSes.

• Just one of the BSSs is the MLD BSS. However, the MLD BSS is part of the same ESS as the affiliated AP BSS.

• There is a field in the multilink element to indicate that the affiliated AP BSS is in a same ESS.

• Group addressed traffic of AP MLD is transmitted on the link corresponding to the AP MLD BSSID.

• Group addressed traffic for the other BSSs are transmitted by the respected affiliated APs using the BSSID corresponding to the BSS.

Figure 7 shows group addressed frames that are transmitted by the AP MLD. The affiliated APs (API and AP2) on each link transmit their own beacon frame together with a copy of group addressed frames forwarded from the AP MLD, originating on LAN1. In addition, API and AP2 also receive their own copy of the group addressed frames originating on LAN1, as they are configured to serve legacy STAs. Legacy STAs cannot receive traffic from AP MLDs as the addressing of legacy frames is different from that of the AP MLD BSS.

Therefore duplicate group addressed frames appear on each affiliated link.

Figure 8 shows another manner of transmission of group addressed frames. The affiliated APs (API and AP2) on each link transmit their own beacon frame. However, GA frames within the AP MLD is suppressed. This manner removes the duplicated GA frames on each affiliated link. Figure 9 shows scenario 3 for MLD behavior. In scenario 3, affiliated APs are operating BSSs that are not part of the same ESS as the AP MLD.

• The affiliated AP transmits group addressed frames for its respective BSS. The AP MLD does not transmit group addressed data frames on that BSS.

• A field in the multi-link element advertises that the BSS of the affiliated AP is not a member of the same ESS as the AP MLD.

Although this scenario may be unusual in practice, it’s important to recognize that different AP MLD configurations changes the way in which Group Addressed frames are treated.

Figure 10 shows group addressed frames that are transmitted by the AP MLD. The affiliated APs (API and AP2) on each link transmit their own beacon frame, together with a copy group addressed frames forwarded from the AP MLD, originating on LAN1. In addition, API and AP2 also receive their own copy of group addressed frames originating on LAN2 and LAN3 respectively, as they are configured to serve legacy STAs. Therefore all group addressed frames are transmitted as they originate from differing LANs and the AP MLD again requires redundancy of its groups addressed frames over the affiliated links.

Therefore duplicate GA frames should not be prevented in the AP MLD.

Figure 11 shows a method for multi-link transmission. The method comprises S101 : transmitting the ML configuration. Wherein the ML configuration is indicative of whether one or more affiliated APs is operating a legacy BSS. The ML configuration is carried on a subfield of an ML element.

In addition, the method may also comprises: performing interaction with another wireless device based on the ML configuration. For example, the method may also comprises S102: performing 4-way handshake or group key handshake based on the ML configuration.

The above steps could be performed by an MLD. The interaction could be between two MLDs, for example, an AP MLD and a non-AP MLD.

Moreover, the ML configuration is further indicative of whether the legacy BSS of the one or more affiliated APs is in the same ESS as the BSS of the wireless device or in a different ESS from that of the BSS of the wireless device.

The ML configuration is used to determine whether to transmit one or more group addressed frame. Therefore, the ML configuration could also be referred to group addressed (GA) configuration. Furthermore, the detailed usages of the ML configuration are described in other related part of the present disclosure. For example, Advertisement of group addressed configuration, Prevention of Group Addressed frame transmission, 4-way handshake based on the GA configuration, or GTK, IGTK security association based on the GA configuration.

Figure 12a shows the format of the new Group Addressed Configuration subfield in the ML element frame. The length of the subfield could be one or more Octets, or several bits (2 or 3 bits). The values of the subfield are as follows:

• A first value (for example, 0) indicates: one or more affiliated APs is not operating a legacy BSS.

• A second value (for example, 1) indicates: one or more affiliated APs is operating a legacy BSS in the same ESS as the AP MLD.

• A third value (for example, 2) indicates: one or more affiliated APs is operating a legacy BSS in different ESSes from that of the AP MLD.

The values of the subfield may also be used to indicate whether one or more affiliated APs is operating a legacy BSS in the same ESS as the non-AP MLD. So the person skilled in the art would arrive similar definition according to the above description.

The backwards compatible way to advertise GA Configuration subfield is to transmit it as a ML element of the MLD BSS. The addition of this subfield to the existing IEEE 802.1 Ibe ML element is shown in Figure 12b.

Figure 12b shows the breakdown of the GA Configuration field within an ML element. The ML element includes at least one of the following field: Element ID, Length, Element ID Extension, Multi-Link Control, Common Info, and Link Info.

The Element ID and Element ID Extension fields are defined to show that this frame is a multilink (ML) element. The Length field indicates the length of the ML element.

The Multi-link Control subfield comprises at least one of a Type subfield, an MLD MAC Address Present subfield and a Reserved subfield. When a value of the Type subfield is equal to 1, the Link Info field comprises Optional Subelements. The MLD MAC Address Present subfield indicates whether a MLD MAC Address is present in another part of the ML element. The Reserved subfield is reserved for future use and is not defined.

The Common Info field defines information for all ML elements. Each Optional Subelement comprises at least of a Subelement ID subfield, together with Length subfield and Data. When the Subelement ID subfield is equal to 1, the Data subfield contains the GA Configuration value.

Advertisement of group addressed configuration

The AP MLD advertises (or sends, or transmits, or broadcasts) a new subfield (Group Addressed Configuration) within the Multi-Link (ML) element indicating information about the configuration of the AP MLD, the LAN and any legacy ST As (for example, the configuration shown in figures 3/5/8). The non-AP MLD receives the configuration of the AP MLD, before the 4-way handshake starts, so that the non-AP MLD can verify set of keys (e.g. either (GTK, IGTK)BSSID_MLD or (GTK, IGTK)BSSID_24 and (GTK, IGTK)BSSID 5)) during the 4- way handshake and subsequent group-key handshake, if necessary.

In Figure 2, message 3, different subfield formats are used to transmit either the (GTK, IGTK)BSSID MLD or the (GTK, IGTK)BSSID 24 and (GTK, IGTK)BSSID 5. Information about the subfield format is not transmitted within message 3 itself.

As there are now two options for subfield formats in message 3 that may be received, the non- AP MLD needs to know the Group Addressed Configuration before the 4-way handshake starts, so that it can determine how to correctly decode the subfields.

The ML element with this subfield will be transmitted by the AP MLD in the following: a beacon frame, a probe response frame. Alternatively, the subfield could also be advertised in Beacon and Probe Response frames as a new subfield within the existing MBSSID (Multi- BSSID) element, as an extra optional subfield at the end of the element.

The AP MLD receives the GA Configuration subfield in an (re)association request from a non- AP MLD. The AP MLD can set a status code, based on the receipt of a correct GA Configuration subfield value, to indicate success or rejection.

If the GA Configuration subfield value received in the (re)association request is valid, the AP MLD may respond with a status code of SUCCESS. If the value of the GA Configuration subfield value received in the (re)association request is not valid, the AP MLD may respond with a status code of REFUSED CAPABILITIES MISMATCH or another valid status code. Alternatively, a new status code could be used within the (re)association exchange, for example, GROUP ADDRESSED ML CONFIGURATION INCOMPATIBLE.

If the subfield is set to 0 or 2, the AP MLD uses (GTK, IGTK)BSSID MLD to encapsulate group addressed traffic for transmission.

If the subfield is set to 1, the AP MLD does not transmit group addressed traffic and relies on the affiliated APs to encapsulate group addressed traffic using link specific keys, (e.g. (GTK, IGTK)BSSID 24, (GTK, IGTK)BSSID 5) for transmission

Prevention of Group Addressed frame transmission

When the configuration of the AP MLD is that of using scenario 2, Group Addressed frames arriving from the LAN are not forwarded to any of the affiliated APs by the AP MLD. The configuration of the AP MLD could be set by a user installing the AP MLD, or maintaining the AP MLD through an external management system. Automatic re-configuration can also occur within the AP MLD as it monitors the number of LAN connections and number of legacy STAs that are connected.

The non-AP MLD receives the Group Addressed Configuration subfield in Beacon and/or Probe Response frames.

The non-AP MLD transmits a (re)association request frame to the AP MLD with the ML element, including the Group Addressed Configuration subfield set to the value received in Beacon or Probe Response frames received from the AP MLD. The non-AP MLD may receive the ML element with the Group Addressed Configuration subfield in the (re)association response frame transmitted by the AP MLD.

4-way handshake based on the GA configuration

During the 4-way handshake when the GA configuration subfield value is 0 or 2:

• The AP MLD transmits the (GTK, IGTK)BSSID MLD in the 4-way handshake message 3.

• The encapsulation of GA frames for transmission is handled by the AP MLD.

• The non-AP MLD verifies that it only receives one set of MLD keys. Each receiving STA needs the keys to de-capsulate GA frames. • The non-AP MLD uses (GTK, IGTK)BSSID MLD to de-capsulate group addressed traffic received from the AP-MLD.

During the 4-way handshake when the GA configuration subfield value is 1 :

• The AP MLD coordinates with the affiliated APs to transmit the link-specific group keys (e.g. (GTK, IGTK)BSSID 24, (GTK, IGTK)BSSID 5) in the 4-way handshake.

• The AP MLD does not transmit and does not encapsulate GA frames.

• To avoid duplication of data frames on the wireless medium, the encapsulation of GA frames is handled by each affiliated AP.

• The non-AP MLD verifies that it receives a set of link specific keys. Each receiving STA needs the appropriate keys to de-capsulate GA frames.

• The non-AP MLD receives group addressed traffic transmitted by an affiliated AP and uses link specific keys, (e.g. (GTK, IGTK)BSSID 24, (GTK, IGTK)BSSID 5) to de- capsulate group addressed traffic.

GTK, IGTK security association based on the GA configuration

• The non-AP MLD associates to the AP MLD on the MLD BSS

• The non-AP MLD and AP MLD establish an SA which includes either the (GTK, IGTK)BSSID MLD associated with the AP MLD, or (GTK, IGTK)BSSID 24 and (GTK, IGTK)BSSID 5 depending on the configuration.

• The Non-AP MLD establishes network and communicates on the LAN using the BSSID MLD as a destination address (DA) and a BSSID.

• The group-key handshake is used to update the GTK, IGTK keys, to refresh the keys. The non-AP MLD needs to know the value of the received GA configuration frame to be able to correctly decode the subfield that contains the GTK, IGTK in the group-key handshake received from the AP MLD.

New functionality provided by the present disclosure within the AP MLD that prevents the unnecessary replication of Group Addressed Frames. This functionality operates depending on whether traffic is routed from a backhaul LAN connection through to legacy STAs that are attached to the AP MLD.

New functionality provided by the present disclosure within the non-AP MLD to determine which keys (e.g. GTK, IGTK) are negotiated based on the configuration of the AP MLD, when the configuration information is received from the AP MLD. The method and device of the present disclosure provide a way to save radio resources and the possible prevention of unnecessary transmission and reception of duplicated Group Addressed frames in an AP MLD and non-AP MLD.

Figure 13 shows a wireless device 500 according to an embodiment of the disclosure. The wireless device 500 may comprise processing circuitry 501 configured to perform, conduct or initiate the various operations of the wireless device 500 described herein. The processing circuitry may comprise hardware and software. The hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors. The wireless device 500 may further comprise memory circuitry, which stores one or more instruction(s) that can be executed by the processor or by the processing circuitry, in particular under control of the software. For instance, the memory circuitry may comprise a non-transitory storage medium storing executable software code which, when executed by the processor or the processing circuitry, causes the various operations of the wireless device 500 to be performed. In one embodiment, the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry executable program code which, when executed by the one or more processors, causes the wireless device 500 to perform, conduct or initiate the operations or methods described herein. The wireless device 500 may further comprise interface circuitry 502, which is used to communicate with another wireless device, for example a wireless device 400.

Figure 14 shows a schematic structural diagram of a multi-link device according to an embodiment of this disclosure. As shown in Figure 14, the multi-link device may include at least one processor 1401, at least one communications interface 1402, at least one memory 1403, and/or at least one bus 1404.

The present disclosure has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed disclosure, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Furthermore, any method according to embodiments of the disclosure may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprise essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.

Moreover, it is realized by the skilled person that embodiments of the wireless device 500, comprise the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, trellis-coded modulation (TCM) encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the solution.

Especially, the processor(s) of the wireless device 500, respectively, may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

A communications apparatus (for example a station or an access point which can perform the above method) is provided, including at least one of the following: a bus, a processor, a storage medium, a bus interface, a network adapter, a user interface, and an antenna (or a transceiver, transmitter and/or receiver), where the bus is configured to connect the processor, the storage medium, the bus interface, and the user interface; the processor is configured to perform the above method; the storage medium is configured to store an operating system and to-be-sent or to-be-received data; the bus interface is connected to the network adapter; the network adapter is configured to implement a signal processing function of a physical layer in a wireless communications network; the user interface is configured to be connected to a user input device; and the antenna is configured to send and receive a signal.

Another aspect of this disclosure provides a computer-readable storage medium, where the computer-readable storage medium stores an instruction, and when the computer-readable storage medium runs on a computer, the computer performs the above method.

Another aspect of this disclosure provides a computer program product including an instruction, where when the computer program product runs on a computer, the computer performs the above method.

Another aspect of this disclosure provides a computer program, where when the computer program runs on a computer, the computer performs the above method.

The foregoing embodiments may be all or partially implemented by using software, hardware, firmware, or any combination thereof. When software is used to implement the embodiments, the embodiments may be all or partially implemented in a form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the procedures or functions according to the embodiments of this disclosure are all or partially generated. The computer may be a general-purpose computer, a dedicated computer, a computer network, or other programmable apparatuses. The computer instructions may be stored in a computer readable storage medium, or may be transmitted from a computer readable storage medium to another computer readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired (for example, a coaxial cable, an optical fiber, or a digital subscriber line (DSL)) or wireless (for example, infrared, radio, or microwave) manner. The computer readable storage medium may be any usable medium accessible by a computer, or may be a data storage device, such as a server or a data center, integrating one or more usable media.

Claims

1. A wireless device for transmitting multi-link, ML, configuration, wherein the wireless device corresponds to one or more affiliated APs, the wireless device being configured to: obtain, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether the one or more affiliated APs is operating a legacy BSS; and transmit, by the wireless device, the ML configuration within a subfield of an ML element.

2. The wireless device according to claim 1, wherein the ML configuration is further indicative of whether the legacy BSS of the one or more affiliated APs is in the same ESS as the BSS of the wireless device or in a different ESS from that of the BSS of the wireless device.

3. The wireless device according to claim 1 or 2, wherein a first value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device; a second value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in a different ESS from that of the wireless device; and a third value of the subfield is indicative of the one or more affiliated APs is not operating a legacy BSS.

4. The wireless device according to any one of claims 1-3, wherein the wireless device is further configured to: suppress the transmission of group addressed frames when one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device.

5. The wireless device according to any one of claims 1-4, wherein the wireless device is further configured to: transmit a group key based on the value of the subfield.

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6. A wireless device for receiving multi-link, ML, configuration, wherein the wireless device corresponds to one or more affiliated STAs, the wireless device being configured to: receive, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether one or more affiliated APs is operating a legacy BSS, wherein the ML configuration is carried on a subfield of an ML element; and perform, by the wireless device, interaction with other wireless devices based on the ML configuration.

7. The wireless device according to claim 6, wherein the ML configuration is further indicative of whether the legacy BSS of the one or more affiliated APs is in the same ESS as the BSS of the wireless device or in a different ESS from that of the BSS of the wireless device.

8. The wireless device according to claim 6 or 7, wherein a first value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device; a second value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in a different ESS from that of the wireless device; and a third value of the subfield is indicative of the one or more affiliated APs is not operating a legacy BSS.

9. The wireless device according to any one of claims 6-8, wherein the wireless device is further configured to: receive a group key based on the value of the subfield.

10. A method for transmitting multi-link, ML, configuration performed by a wireless device, wherein the wireless device corresponds to one or more affiliated APs, the method comprising: obtaining, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether the one or more affiliated APs is operating a legacy BSS; and transmitting, by the wireless device, the ML configuration within a subfield of an ML element.

11. The method according to claim 10, wherein the ML configuration is further indicative of whether the legacy BSS of the one or more affiliated APs is in the same ESS as the BSS of the wireless device or in a different ESS from that of the BSS of the wireless device.

12. The method according to claim 10 or 11, wherein a first value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device; a second value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in a different ESS from that of the wireless device; and a third value of the subfield is indicative of the one or more affiliated APs is not operating a legacy BSS.

13. The method according to any one of claims 10-12, further comprising: suppressing the transmission of group addressed frames when one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device.

14. The method according to any one of claims 10-13, further comprising: transmitting a group key based on the value of the subfield.

15. A method for receiving multi-link, ML, configuration performed by a wireless device, wherein the wireless device corresponds to one or more affiliated STAs, the method comprising: receiving, by the wireless device, the ML configuration, wherein the ML configuration is indicative of whether the one or more affiliated APs is operating a legacy BSS, wherein the ML configuration is carried on a subfield of an ML element; and performing, by the wireless device, interaction with other wireless devices based on the ML configuration.

16. The method according to claim 15, wherein the ML configuration is further indicative of whether the legacy BSS of the one or more affiliated APs is in the same ESS as the BSS of the wireless device or in a different ESS from that of the BSS of the wireless device.

17. The method according to claim 15 or 16, wherein a first value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in the same ESS as the wireless device; a second value of the subfield is indicative of the one or more affiliated APs is operating a legacy BSS in a different ESS from that of the wireless device; and a third value of the subfield is indicative of the one or more affiliated APs is not operating a legacy BSS.

18. The method according to any one of claims 15-17, further comprising: receive a group key based on the value of the subfield.

19. A computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is run on a computer, the computer is enabled to perform the method according to any one of claims 10 to 18.

20. A chip system, comprising a processor, configured to invoke a computer program from a memory and run the computer program, so that a communications device on which the chip system is installed performs the method according to any one of claims 10 to 18.

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