US-20260129577-A1 - UPLINK-ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS (UL-OFDMA) TRIGGER-BASED TRANSMISSION ACROSS MULTIPLE LINKS FOR MULTI-LINK OPERATION (MLO)

Abstract

A method performed by an access point multi-link device (AP MLD) to coordinate trigger-based uplink transmissions across multiple wireless links from a station MLD (STA MLD). The method involves determining an allocation of groups of frequency subcarriers to be used on each wireless link of the multiple wireless links for simultaneous uplink transmission from the STA MLD to the AP MLD; including, in a single trigger frame or in each of multiple trigger frames, information indicating the allocation of groups of frequency subcarriers to be used on each wireless link of the multiple wireless links; and transmitting the single trigger frame on one wireless link of the multiple wireless links, or the multiple trigger frames simultaneously across the multiple wireless links to the STA MLD.

Inventors

• Sachin Dinkar Wakudkar
• Brian D. Hart
• Ardalan Alizadeh
• Sanjay K. KATABATHUNI
• Venkataprasad CHIRREDDY
• Jegan MANOHARAN

Assignees

• CISCO TECHNOLOGY, INC.

Dates

Publication Date

20260507

Application Date

20241105

Claims (20)

1. 1 . A method by an access point multi-link device (AP MLD) to coordinate trigger-based uplink transmissions across multiple wireless links among wireless links setup between the AP MLD and a station MLD (STA MLD), comprising: determining an allocation of groups of frequency subcarriers to be used on each wireless link of the multiple wireless links for simultaneous uplink transmission from the STA MLD to the AP MLD; including, in a single trigger frame or in each of multiple trigger frames, information indicating the allocation of groups of frequency subcarriers to be used on each wireless link of the multiple wireless links; and transmitting the single trigger frame on one wireless link of the multiple wireless links, or the multiple trigger frames simultaneously across the multiple wireless links to the STA MLD.
2. 2 . The method of claim 1 , wherein the information indicating the allocation of groups of subcarriers comprises information indicating Resource Unit (RU) position and RU size to be used on each wireless link of the multiple wireless links, wherein a Resource Unit denotes a group of frequency subcarriers.
3. 3 . The method of claim 1 , further comprising simultaneously receiving multiple triggered uplink transmissions, one triggered uplink transmission on each wireless link of the multiple wireless links, from the STA MLD.
4. 4 . The method of claim 3 , further comprising transmitting on one wireless link of the multiple wireless links or on all the multiple wireless links, a multi-link multi-STA block acknowledgment frame with an identifier for a STA of the STA MLD to acknowledge reception by the AP MLD of a triggered uplink transmission from the STA of the STA MLD.
5. 5 . The method of claim 4 , wherein the multi-link multi-STA block acknowledgment frame comprises a single block acknowledgment bitmap for all of the multiple wireless links after pooling all received Media Access Control (MAC) Protocol Data Units (MPDUs) from all the multiple wireless links.
6. 6 . The method of claim 4 , wherein the multi-link multi-STA block acknowledgment frame includes link identifier(s), association identifier(s) and traffic identifier(s) to indicate acknowledge of reception of triggered uplink transmissions from the STA MLD.
7. 7 . The method of claim 1 , wherein transmitting comprises transmitting to the STA MLD the single trigger frame on one wireless link of the multiple wireless links.
8. 8 . The method of claim 7 , wherein the single trigger frame is used as a synchronization reference by the STA MLD for timing and carrier frequency offset for the multiple wireless links.
9. 9 . The method of claim 1 , wherein transmitting comprises transmitting the multiple trigger frames to the STA MLD, each of the multiple trigger frames being transmitted on a corresponding one of the multiple wireless links.
10. 10 . The method of claim 9 , wherein the multiple trigger frames transmitted across the multiple wireless links are synchronized so that in turn triggered uplink transmissions from the STA MLD are synchronized across the multiple wireless links.
11. 11 . The method of claim 1 , wherein the information indicating the allocation of groups of subcarriers for each of the multiple wireless links is included in a Trigger Dependent User Info sub-field of a User Info field of the single trigger frame or in each of the multiple trigger frames.
12. 12 . The method of claim 1 , further comprising: including in a Target Wake Time (TWT) control frame information to indicate alignment of TWT schedule periods across the multiple wireless links, and information to indicate single trigger multi-link synchronization across the multiple wireless links with the single trigger frame or multi trigger multi-link synchronization across the multiple wireless links with the multiple trigger frames.
13. 13 . An apparatus comprising: a plurality of access point modules each configured to wireless communicate over an associated wireless link of a plurality of wireless links for an access point multi-link device (AP MLD) with a station MLD (STA MLD); and a processor coupled to the plurality of access point modules, the processor configured to perform operations including: determining an allocation of groups of frequency subcarriers to be used on each wireless link of the plurality of wireless links for simultaneous uplink transmission from the STA MLD to the AP MLD; including, in a single trigger frame or in each of multiple trigger frames, information indicating the allocation of groups of frequency subcarriers to be used on each wireless link of the plurality of wireless links; and causing the single trigger frame to be transmitted by one of the plurality of access point modules on one wireless link of the plurality of wireless links, or causing the plurality of access point modules to each simultaneously transmit the multiple trigger frames across the plurality of wireless links to the STA MLD.
14. 14 . The apparatus of claim 13 , wherein the information indicating the allocation of groups of subcarriers comprises information indicating Resource Unit (RU) position and RU size to be used on each wireless link of the plurality of wireless links, wherein a Resource Unit denotes a group of frequency subcarriers.
15. 15 . The apparatus of claim 13 , wherein the plurality of access point modules are configured to simultaneously receive multiple triggered uplink transmissions, one triggered uplink transmission on each wireless link of the plurality of wireless links, from the STA MLD.
16. 16 . The apparatus of claim 15 , wherein the processor is configured to cause at least one access point module of the plurality of access point modules to transmit on one wireless link of the plurality of wireless links or the plurality of access point modules on respective wireless links of the plurality of wireless links, a multi-link multi-STA block acknowledgment frame with an identifier for a STA of the STA MLD to acknowledge reception by the AP MLD of a triggered uplink transmission from the STA of the STA MLD.
17. 17 . The apparatus of claim 16 , wherein the multi-link multi-STA block acknowledgment frame includes link identifier(s), association identifier(s) and traffic identifier(s) to indicate acknowledge of reception of triggered uplink transmissions from the STA MLD.
18. 18 . The apparatus of claim 16 , wherein the multi-link multi-STA block acknowledgment frame comprises a single block acknowledgment bitmap for all of the plurality of wireless links after pooling all received Media Access Control (MAC) Protocol Data Units (MPDUs) from all the plurality of wireless links.
19. 19 . The apparatus of claim 13 , wherein the information indicating the allocation of groups of subcarriers for each of the plurality of wireless links is included in a Trigger Dependent User Info sub-field of a User Info field of the single trigger frame or in each of the multiple trigger frames.
20. 20 . The apparatus of claim 13 , wherein the processor is further configured to include in a Target Wake Time (TWT) control frame information to indicate alignment of TWT schedule periods across the plurality of wireless links, and information to indicate single trigger multi-link synchronization across the plurality of wireless links with the single trigger frame or multi trigger multi-link synchronization across the plurality of wireless links with the multiple trigger frames.

Description

TECHNICAL FIELD The present disclosure relates to wireless networking. BACKGROUND Networking architectures have grown increasingly complex in communications environments, particularly wireless networking environments. For wireless local area networks, Institute of Electrical and Electronics Engineers (IEEE) 802.11be (Wi-Fi® 7) defines various features to facilitate Multi-Link Operation (MLO) for Multi-Link Devices (MLDs) that are capable of associating and simultaneously exchange data traffic on multiple Radio Frequency (RF) bands. With MLO, it is possible to increase the throughput for a client device by aggregating multiple links. Currently, in trigger-based transmissions for uplink orthogonal frequency division multiple access (UL-OFDMA), a user information (info) field includes a sub-field in which Resource Units (RUs) are assigned per link for UL-OFDMA. As a result, a client device may not be able to achieve higher throughout since the trigger-based transmission is associated with just a single link. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a system that may be implemented to enable trigger-based transmissions across multiple links for MLO in a wireless local area network (WLAN), according to an example embodiment. FIG. 2A is a diagram depicting a technique to transmit a trigger frame on one wireless link to coordinate simultaneous uplink transmissions from a STA MLD to an AP MLD, according to an example embodiment. FIG. 2B is a diagram depicting a technique to transmit a trigger frame on multiple wireless links to coordinate simultaneous uplink transmissions from a STA MLD to an AP MLD, according to an example embodiment. FIG. 2C is a diagram showing use of reserved fields in a Block Ack (BA) frame to indicate a specialized multi-link multi-STA Block Ack to be sent by an AP MLD, according to an example embodiment. FIG. 2D is a diagram showing how an indication of a BA type encoding to signal a multi-link multi-STA BA frame may be achieved, according to an example embodiment. FIG. 2E is a diagram showing an example of a format of a BA information field for a multi-link multi-STA BA frame to provide per link, per association identifier and per traffic identifier BA information. FIG. 3 is a diagram depicting including RU allocation information in a sub-field of a trigger frame, according to an example embodiment. FIG. 4A is a diagram that illustrates alignment of Target Wake Time (TWT) schedules to support synchronization of uplink transmissions across multiple links, according to an example embodiment. FIG. 4B is a diagram illustrating a field in a TWT control frame that may be modified to include information on a type of trigger frame synchronization (single trigger frame or multiple trigger frames) to be used by an AP MLD, according to an example embodiment. FIG. 5 illustrates a flow of a method performed by an AP MLD for coordinating simultaneous uplink transmissions from a STA MLD, according to an example embodiment. FIG. 6 is a hardware block diagram of an AP MLD configured to perform functions associated with operations discussed in connection with embodiments herein. DETAILED DESCRIPTION Overview Innovations in wireless access points (APs) and devices have led to the development of Multi-Link Devices (MLDs) that are capable of Multi-Link Operation (MLO). For MLO, MLDs can associate and simultaneously exchange data traffic on multiple Radio Frequency (RF) bands, such as 2.4 Gigahertz (GHz), 5 GHz, and/or 6 GHz bands. MLDs can include AP MLDs and non-AP MLDs, often referred to as MLD client devices, MLD-STAs (STA=abbreviation of station), STA MLDs; and the term ‘client’ include a STA MLD. As referred to herein, the terms ‘link’, ‘wireless link’, and variations thereof can refer to a wireless connection through which a STA (of a STA MLD) can wirelessly connect to/access the wireless connection provided by an AP (of an AP MLD). Each link uses a different channel of a certain bandwidth. Embodiments presented herein enable coordination of trigger-based transmissions across multiple MLO links so that a MLD client device (STA MLD or non-AP MLD) can take advantage of higher throughput on uplink transmissions using UL-OFDMA across multiple links. An AP MLD is configured to send a trigger frame on one link or on all links to trigger a non-AP MLD (e.g., a STA MLD) to transmit on multiple links. In one embodiment, a method is provided that is performed by an access point multi-link device (AP MLD) to coordinate trigger-based uplink transmissions across multiple wireless links from a station MLD (STA MLD). The method involves determining an allocation of groups of frequency subcarriers to be used on each wireless link of the multiple wireless links for simultaneous uplink transmission from the STA MLD to the AP MLD; including, in a single trigger frame or in each of multiple trigger frames, information indicating the allocation of groups of frequency subcarriers to be used on each wireles