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US-20260128763-A1 - METHODS AND APPARATUS FOR RESOLVING STATION ID CONFLICT IN COORDINATED BEAMFORMING

US20260128763A1US 20260128763 A1US20260128763 A1US 20260128763A1US-20260128763-A1

Abstract

Methods and apparatus for configuring coordinated beamforming among multiple APs which mitigate or prevent station ID collisions between STAs associated with different collaborating Basic Service Sets are provided. A common BSS color is used for all STAs in the U-SIG field of a Co-BF PPDU. A disambiguation bit may be used in the UHR-SIG field to determine with which of two APs a STA is associated. The Initial Control Frame and Initial Control Response sequence can be leveraged to assign new STA IDs to STAs with conflicting STA IDs. STA ID conflicts can be prevented by assigning overlapping APs unique sets of most significant bits to use for all of their STA IDs.

Inventors

  • Mahmoud Hasabelnaby
  • Jung Hoon SUH
  • Yan Xin
  • Osama Aboul-Magd
  • Sara NOROUZI

Assignees

  • HUAWEI TECHNOLOGIES CO., LTD.

Dates

Publication Date
20260507
Application Date
20250221

Claims (20)

  1. 1 . A method comprising, at a sharing access point (AP) of a wireless communication network: transmitting, towards a shared AP of the wireless communication network, a first initial control frame (ICF) comprising: an indication of a common basic service set (BSS) color to be used in a joint transmission of a coordinated beamforming (Co-BF) downlink (DL) physical layer protocol data unit (PPDU) by the sharing AP and the shared AP; and an indication of a first plurality of stations (STAs) associated with the sharing AP; and receiving, from the shared AP, an initial control response (ICR) indicative of a participation of the shared AP in the joint transmission of the Co-BF DL PPDU, and indicative of a second plurality of STAs associated with the shared AP.
  2. 2 . The method of claim 1 , further comprising: transmitting, towards the shared AP, a Co-BF trigger for the joint transmission of the Co-BF DL PPDU; and transmitting the Co-BF DL PPDU having the common BSS color.
  3. 3 . The method of claim 1 , wherein transmitting the first ICF towards the shared AP comprises transmitting the first ICF towards both the shared AP and the first plurality of STAs, the ICF further comprising an indication of a first set of STA identifiers (IDs) for the first plurality of STAs.
  4. 4 . The method of claim 1 , further comprising: transmitting, towards the first plurality of STAs, an indication of a first set of STA identifiers (IDs) for the first plurality of STAs, STA IDs of the first set of STA IDs being distinct from STA IDs of a second set of STA IDs for the second plurality of STAs.
  5. 5 . The method of claim 4 , wherein the STA IDs of the first set of STA IDs and the STA IDs of the second set of STA IDs are selected from an Association Identifier (AID) pool comprising 2006 AIDs.
  6. 6 . The method of claim 4 , wherein each STA ID of the first set of STA IDs comprises a same 2 or 3 bit BSS ID.
  7. 7 . The method of claim 3 , further comprising: receiving, from the shared AP, a second ICF comprising an indication of a second set of STA IDs associated with the shared AP, STA IDs within the second set of STA IDs being distinct from STA IDs within the first set of STA IDs.
  8. 8 . The method of claim 1 , wherein the first ICF further comprises one or more of: a multi-AP (MAP) agreement identifier (ID) associated with the joint transmission of the Co-BF DL PPDU; a Co-BF instance ID associated with the joint transmission of the Co-BF DL PPDU; an indication of a first set of STA IDs for the first plurality of STAs, the STAs of the first plurality of STAs being ready for receiving the joint transmission of the Co-BF DL PPDU; a 1-bit indication of a presence of an enhanced multi-link single radio (eMLSR) STA or a dynamic power saving (DPS) STA in the first plurality of STAs; a carrier frequency offset (CFO) precorrection value; precoding parameters; a Sounding Dialog Token Number; and additional control information associated with the joint transmission of the Co-BF DL PPDU.
  9. 9 . The method of claim 1 , wherein the ICR further comprises one or more of: a 1-bit indication of a presence of an enhanced multi-link single radio (eMLSR) STA or a dynamic power saving (DPS) STA in the second plurality of STAs; a carrier frequency offset (CFO) precorrection value; precoding parameters; and a Sounding Dialog Token Number.
  10. 10 . The method of claim 1 , further comprising: determining that no STA within the first plurality of STAs can participate in receiving the joint transmission of the Co-BF DL PPDU; and sharing, with the shared AP, a transmission opportunity (TXOP) associated with the joint transmission of the Co-BF DL PPDU, using Coordinated Time Division Multiple Access (Co-TDMA).
  11. 11 . The method of claim 1 , wherein the common BSS color is one of: a Co-BF instance ID associated with the joint transmission of the Co-BF DL PPDU; a BSS color of the sharing AP; a pre-negotiated BSS color; and a negotiated value.
  12. 12 . The method of claim 1 , wherein the first ICF is a trigger frame or a public action frame.
  13. 13 . A method comprising, at a shared access point (AP) of a wireless communication network: receiving, from a sharing AP of the wireless communication network, a first initial control frame (ICF) comprising: an indication of a common basic service set (BSS) color to be used in a joint transmission of a coordinated beamforming (Co-BF) downlink (DL) physical layer protocol data unit (PPDU) by the sharing AP and the shared AP; and an indication of a first plurality of stations (STAs) associated with the sharing AP; and transmitting, towards a second plurality of STAs associated with the shared AP, an indication of the common BSS color.
  14. 14 . The method of claim 13 , further comprising: transmitting, towards the sharing AP and the second plurality of STAs, a second ICF indicative of a participation of the shared AP in the joint transmission of the Co-BF DL PPDU and indicative of the second plurality of STAs, the second ICF comprising the indication of the common BSS color.
  15. 15 . The method of claim 13 , further comprising: transmitting, towards the second plurality of STAs, an indication of a first set of STA identifiers (IDs) for the second plurality of STAs, STA IDs of the first set of STA IDs being distinct from STA IDs of a second set of STA IDs for the first plurality of STAs associated with the sharing AP.
  16. 16 . The method of claim 15 , wherein the indication of the common BSS color and the indication of the first set of STA IDs are transmitted jointly.
  17. 17 . The method of claim 15 , wherein the STA IDs of the first set of STA IDs and the STA IDs of the second set of STA IDs are selected from an Association Identifier (AID) pool comprising 2006 AIDs.
  18. 18 . The method of claim 15 , wherein each STA ID of the first set of STA IDs comprises a same 2 or 3 bit BSS ID.
  19. 19 . The method of claim 15 , further comprising: receiving, from the sharing AP, an indication of the second set of STA IDs, the second set of STA IDs including a first STA ID, a STA of the second plurality of STAs having the first STA ID, wherein the first set of STA IDs includes a new STA ID for the STA of the second plurality of STAs, the new STA ID being distinct from the first STA ID.
  20. 20 . The method of claim 19 , wherein the first ICF comprises the indication of the second set of STA IDs.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63/727,275, filed Dec. 3, 2024, U.S. Provisional Patent Application No. 63/717,589, filed Nov. 7, 2024, the contents of which are incorporated herein by reference. FIELD OF THE INVENTION The present invention pertains to wireless communication systems, and in particular to a method and apparatus for coordinated beamforming transmissions in wireless communication systems. BACKGROUND A Wireless Local Area Network (LAN) according to IEEE 802.11 specifications has at least one Basic Service Set (BSS) composed of an access point (AP) and one or more non-access point stations (STAs) associated therewith. Beamforming is the systematic driving of pluralities of antennas belonging to one or more APs or STAs to create constructive interference in a primary direction to boost the signal power reaching a target receiver while nulling the signal in the direction of unintended receivers. Basic service sets can be said to overlap when regions of space lie within a useful communication range of more than one Access Point. In Wireless LAN scenarios with Overlapping Basic Service Sets (OBSSs), Coordinated Beamforming (Co-BF or COBF) is a technique in which multiple Access Points (APs) collaborate to optimize downlink (DL) transmissions, improving signal strength and minimizing interference for their associated non-AP-STAs (Stations) within a shared wireless environment. In a typical Co-BF setup, two APs—the “sharing AP” and the “shared AP”—synchronize their downlink transmissions to create a coordinated beam, nullifying their signals towards the STAs served by each AP during a specific Transmission Opportunity (TXOP). This strategy mitigates interference from neighboring networks, allowing for more efficient spectrum utilization and enhancing overall network performance. The coordination between the sharing AP and shared AP is critical for improving the reliability and efficiency of wireless transmissions in dense environments, such as office buildings or residential areas with multiple networks operating in proximity. By minimizing interference and optimizing the downlink signals toward non-AP STAs, Co-BF can significantly boost throughput and reduce congestion, ultimately leading to better user experiences in wireless networks. As detailed in the approved motions #99 and #114 for IEEE 802.11bn standard, there are certain restrictions placed on the number of APs and STAs involved in Co-BF transmissions. Specifically, IEEE 802.11bn standard limits the number of APs to two and the maximum number of STAs to four in a Co-BF transmission. This limitation is designed to simplify the coordination process and keep the system's complexity manageable. This is also because, in typical scenarios, if more than three users belong to a single AP, the AP may not have sufficient resources (spatial dimensions) available to nullify signals effectively, which can degrade performance. By limiting the total number of users to four, the system can provide good spatial multiplexing opportunities while maintaining processing simplicity, akin to regular Multi-User Multiple Input Multiple Output MU-MIMO (Multi-User MIMO) configurations. Additionally, IEEE 802.11bn standard places further constraints to simplify both signaling and testing by capping the maximum total spatial streams to four and limiting each STA to a maximum of two spatial streams. Methods of configuration of coordinated beamforming to resolve station address conflicts in a multi-AP collaboration scenario are therefore desired that mitigate one or more deficiencies in the prior art, to enhance the coordination of downlink transmissions between APs, ensuring reliable communication and optimizing network performance. SUMMARY The primary technical challenge addressed by embodiment of the present disclosure is the STA ID (Station Identifier) conflict issue in Coordinated Beamforming (Co-BF, COBF) downlink transmissions. Since STA IDs are typically assigned independently by each AP in a Co-BF setup, there is a risk of collisions when multiple APs transmit simultaneously within the same downlink PPDU (Physical Protocol Data Unit). This can lead to confusion for non-AP STAs, as they may be unable to determine which BSS (Basic Service Set) or AP the received transmission belongs to, which can result in incorrect data reception or interference. Another issue is the efficient utilization of the Physical Layer (PHY) preamble, which is limited in terms of available bits. Current solutions in the prior art often require dedicating bits in the PHY preamble, which is not optimal given the value of every bit in this space. This can lead to wasted resources and a reduction in overall system efficiency. Furthermore, scalability is an important concern. Existing solutions in the prior art typically support only two APs in Co-BF at a time, which limits their applicability in future wireless