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US-20260128768-A1 - MULTI-LINK OPERATION ASSISTED SECTOR LEVEL SWEEP PROCEDURE FOR MMWAVE LINK

US20260128768A1US 20260128768 A1US20260128768 A1US 20260128768A1US-20260128768-A1

Abstract

A wireless communication method, system, and apparatus perform analog beamforming training by generating training control information regarding a mmWave link between an AP MLD and a non-AP MLD, where the training control information includes a value to indicate if the non-AP MLD includes a directional receiver or an omni-directional receiver, where the AP MLD transmits a training PPDU sequence to the non-AP MLD through the mmWave link under control of the training control information, and then receives a first signal quality feedback message from the non-AP MLD through the non-mmWave link in response to the non-AP MLD detecting and measuring a first signal quality measure based on the training PPDU sequence received by the non-AP MLD under control of the training control information, where the AP MLD uses the first signal quality measure to determine antenna weight vectors for analog beamforming ranking of the AP MLD.

Inventors

  • XIAYU ZHENG
  • Liwen Chu
  • Rui Cao
  • Hongyuan Zhang

Assignees

  • NXP USA, INC.

Dates

Publication Date
20260507
Application Date
20251021

Claims (20)

  1. 1 . A wireless communication method for performing analog beamforming training to establish a mmWave link by a first wireless multi-link device (MLD) in accordance with Institute of Electrical and Electronics Engineers (IEEE) 802.11 protocol, comprising: generating training control information regarding a millimeter wave (mmWave) link between the first wireless MLD and a second wireless MLD, where the training control information includes a first indicator if the second wireless MLD includes a directional receiver and includes a second indicator if the second wireless MLD includes an omni-directional receiver; transmitting, by the first wireless MLD, a first training PPDU sequence to the second wireless MLD through the mmWave link under control of the training control information; and receiving, by the first wireless MLD, a first signal quality feedback message from the second wireless MLD through the non-mmWave link in response to the second wireless MLD detecting and measuring a first signal quality measure based on the first training PPDU sequence received by the second wireless MLD under control of the training control information, where the first wireless MLD uses the first signal quality measure to determine a plurality of transmit antenna weight vectors (AWV) or beam ranking for analog beamforming of the first wireless MLD.
  2. 2 . The wireless communication method of claim 1 , further comprising: receiving, by the first wireless MLD, a second training PPDU sequence from the second wireless MLD through the mmWave link under control of the training control information where there is no Tx/Rx beam reciprocity between the first and second wireless MLDs; measuring, by the first wireless MLD, a second signal quality measure based on the second training PPDU sequence received by the first wireless MLD; and transmitting, by the first wireless MLD, a second signal quality feedback message to the second wireless MLD through the non-mmWave link which includes the second signal quality measure for use by the second wireless MLD to determine the plurality of transmit antenna weight vectors (AWV) or beam ranking for analog beamforming of the second wireless MLD.
  3. 3 . The wireless communication method of claim 1 , where generating the training control information comprises: transmitting, by the first wireless MLD, a first control frame regarding the mmWave link to the second wireless MLD through the non-mmWave link between the first wireless MLD and the second wireless MLD; and receiving, by the first wireless MLD, an acknowledgement response message sent by the second wireless MLD through the non-mmWave link in response to the second wireless MLD receiving the training control information, where information contained in the first control frame and acknowledgement response message are used by the first wireless MLD and second wireless MLD to negotiate the training control information.
  4. 4 . The wireless communication method of claim 3 , where the first wireless MLD transmits the first training PPDU sequence after waiting for a specified time delay after receiving the acknowledgement response message.
  5. 5 . The wireless communication method of claim 4 , where the specified time delay may be a predefined Interframe space (IFS) or a medium access time with random backoff based on medium status.
  6. 6 . The wireless communication method of claim 1 , where the training control information specifies a plurality of analog beamforming training parameters comprising a specified number of training PPDUs, a specified transmit sector sweep (TXSS) configuration, a specified receive sector sweep (RXSS) configuration, and indicator information specifying if the second wireless MLD includes an omni-directional receiver or a directional receiver.
  7. 7 . The wireless communication method of claim 1 , where the first wireless MLD transmits the first training PPDU sequence by applying a different transmit AWV or beam to each training PPDU in the first training PPDU sequence.
  8. 8 . The wireless communication method of claim 7 , where the second wireless MLD uses an omni-directional beam receiver to detect and measure the first signal quality measure from the first training PPDU sequence.
  9. 9 . The wireless communication method of claim 7 , where the first wireless MLD generates the first training PPDU sequence wherein each training PPDU comprises a non-training field and a training field, and where the second wireless MLD uses an omni-directional beam receiver to detect and measure only the non-training field from each training PPDU.
  10. 10 . The wireless communication method of claim 9 , where the second wireless MLD uses directional receive beams to measure the training field from each detected training PPDU and to determine a receive beam ranking for reverse direction Tx beam ranking when there is Tx/Rx beam reciprocity between the first and second wireless MLDs.
  11. 11 . The wireless communication method of claim 7 , where the second wireless MLD uses a directional beam receiver to detect and measure the first signal quality measure from the first training PPDU sequence.
  12. 12 . The wireless communication method of claim 11 , where the first wireless MLD uses announcement frame exchange or a polling packet to solicit the second wireless MLD to transmit the first signal quality feedback message as a reference indicator to configure different receive directional beams for the different rounds of training PPDU sequences.
  13. 13 . The wireless communication method of claim 11 , where the training control information configures the first wireless MLD to initiate multiple rounds of training PPDU sequences with same transmit AWVs and configures the second wireless MLD to use different receive directional beams for the multiple rounds of training PPDU sequences.
  14. 14 . The wireless communication method of claim 11 , where the first wireless MLD transmits the first training PPDU sequence a plurality of up to N times to the second wireless MLD through the mmWave link under control of the training control information before receiving the first signal quality feedback message, where N is a negotiated integer number of receive directional beams.
  15. 15 . The wireless communication method of claim 11 , where the first wireless MLD transmits the first training PPDU sequence one or more times to the second wireless MLD through the mmWave link under control of the training control information until receiving the first signal quality feedback message which indicates a mmWave link has been established.
  16. 16 . The wireless communication method of claim 1 , where the first signal quality feedback message may be initiated by the second wireless MLD via medium access on the non-mmWave link or solicited by the first wireless MLD via a beamforming polling packet on the non-mmWave link.
  17. 17 . The wireless communication method of claim 16 , where the first signal quality feedback message solicited by the first wireless MLD comprises a predetermined indicator value if the second wireless MLD does not detect any packet from the first training PPDU sequence.
  18. 18 . The wireless communication method of claim 3 , where the first wireless MLD transmits a plurality of up to N training PPDU sequences, including the first training PPDU sequence, to the second wireless MLD through the mmWave link under control of the training control information before receiving the first signal quality feedback message, where the first wireless MLD receives the acknowledgment response message and then waits for a first fixed time interval before transmitting the first training PPDU sequence, and where the first wireless MLD separates transmission of successive training PPDU sequences in the plurality up to N training PPDU sequences by a second fixed time interval.
  19. 19 . The wireless communication method of claim 18 , where the first wireless MLD transmits the plurality of up to N training PPDU sequences without transmitting an announcement frame or polling packet on the non-mmWave link for each training PPDU sequence.
  20. 20 . The wireless communication method of claim 18 , where the first fixed time interval is a predefined Interframe space (IFS) which the second wireless MLD uses with a defined training PPDU duration, a number of Tx beams, and the second fixed time interval to calculate a switching time for switching between different directional receive beams for receiving each training PPDU sequence.

Description

CROSS-REFERENCE TO RELATED APPLICATION AND PRIORITY CLAIM This application claims the benefit of U.S. Provisional Patent Application No. 63/714,927 entitled “MLO Assisted Sector Level Sweep Procedure for mmWave Link” filed Nov. 1, 2024, which is incorporated by reference in its entirety as if fully set forth herein. BACKGROUND Field The present disclosure is directed in general to communication networks. In one aspect, the present disclosure relates generally to wireless local area network (WLAN) implementing the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard and any other standards and/or networks that can provide wireless transfer of data over a millimeter wave link. Description of the Related Art An ever-increasing number of relatively inexpensive, low power wireless data communication services, networks and devices have been made available over the past number of years, promising near wire speed transmission and reliability. Enabling technology advances in the area of wireless communications, various wireless technology standards (including for example, the IEEE Standards 802.11a/b/g, 802.11n, 802.11ad, 802.11ac, 802.11ax, 802.11ay, and 802.11be and their updates and amendments, as well as the IEEE Standard 802.11bq now in the process of being developed) have been introduced that are known to persons skilled in the art and are collectively incorporated by reference as if set forth fully herein fully. For example, the 802.11be amendment to the IEEE 802.11 standard (“Wi-Fi 7”) added support for Multi-Link Operation (MLO). This feature increases capacity by simultaneously sending and receiving data across different frequency bands and channels (e.g., 2.4 GHz, 5 GHz, and 6 GHz). With MLO, for example, an access point multi-link device (AP MLD) simultaneously establishes multiple links with a non-AP MLD client over more than one frequency band in order to increases throughput, reduce latency, and improve reliability. Multi-Link Operation also supports various operating modes. Another advance with wireless communications was proposed in the 802.11ad, 802.11ay, and 802.11aj standards which defined wireless communication standards in the 60 GHz or 45 GHz (China) mmWave band. In this area, the beamforming with a large number of antennas is identified as one of the most important mechanism in mmWave bands to compensate for the high pathloss for directional multi-gigabit communication (DMG, e.g., see P802.11-REVme/D4.0, August 2023). To balance the trade-off between cost and performance, the implementation of beamforming is composed of both analog beamforming and/or digital beamforming (or hybrid beamforming for MIMO case) for DMG beamforming. In the existing DMG approach for mmWave communication link signaling, there is an initial sector level sweep (SLS) phase to find the transmit and receive antenna weight vectors (AWV) for analog beamforming to enable the AP and STA to communicate, where the AP is the SLS initiator and the SLS is usually conducted periodically based on the beacon interval. In addition, there is a beam refinement protocol (BRP) phase to further train the device's receive and transmit antenna array(s) and improve its transmit (Tx) and receive (Rx) antenna configuration on top of SLS using an iterative procedure with BRP frame. When multiple Tx/Rx RF chains (each connecting to an antenna array) are enabled, the digital beamforming training could be further conducted once the analog beaming with BRP procedure is done and the analog AWVs are applied on both Tx/Rx RF chains. Under the existing DMG approach for mmWave communication link signaling, all the beamforming training packet exchanges are conducted in the mmWave band as a standalone mode. In addition, a special control PHY is required that is defined with 15 dB sensitivity margin over the lowest MCS to assist the training procedure, which also complicates the beamforming protocol design. As seen from the foregoing, there are performance vs. complexity vs. hardware cost trade-offs with the existing DMG approach for mmWave communication link signaling which are non-trivial to solve, and as a result, these standards with the DMG approach are not widely adopted in the market due to the complexity and high cost. BRIEF DESCRIPTION OF THE DRAWINGS The present invention may be understood, and its numerous objects, features and advantages obtained, when the following detailed description of a preferred embodiment is considered in conjunction with the following drawings. FIG. 1 is a simplified block diagram of a multi-link communications system in accordance with selected embodiments of the present disclosure. FIG. 2 is a simplified block diagram of a wireless communications system in accordance with selected embodiments of the present disclosure. FIG. 3 illustrates an example of a frame exchange sequence for an MLO-assisted SLS procedure for establishing a mmWave link with an omni-directional receiver and transmitter which ha