60GHz beam management for wireless local area network (WLAN)

Abstract

The invention provides a method, a device and a system for increasing carrier frequency of wireless communication in a wireless local area network. Some implementations are more particularly directed to beamforming training operations that support wireless communications on carrier frequencies above 7 GHz. In some aspects, a beamforming initiator can initiate a beamforming training operation by transmitting a number (N) of beamforming training (BFT) packets in N TX beam directions, respectively, on carrier frequencies above 7 GHz. A beamforming responder receives one or more of the BFT packets and provides feedback to the beamforming initiator indicating the TX beam direction associated with the BFT packet having the highest received signal power. In some aspects, when the beamforming initiator trains its TX antenna, the beamforming responder can concurrently train its RX antenna for RX beamforming. In some other aspects, the beamforming responder can train its RX antenna after the beamforming initiator trains its TX antenna.

Description

[0001] Cross-references

[0002] This patent application claims priority to U.S. patent application No. 17 / 746,623, filed by Yang et al. on May 17, 2022, entitled “60GHZ BEAM MANAGEMENT FOR WIRELESS LOCAL AREA NETWORKS (WLANS)”, which is assigned to the assignee of this application and is expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to wireless communications, and more particularly, to 60 GHz beam management for wireless local area networks (WLANs). Background Art

[0004] A wireless local area network (WLAN) may be formed by one or more access points (APs) that provide a shared wireless communication medium for use by several client devices, also referred to as stations (STAs). The basic building block of a WLAN that complies with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards is a basic service set (BSS) managed by an AP. Each BSS is identified by a basic service set identifier (BSSID) announced by the AP. The AP periodically broadcasts beacon frames to enable any STA within the wireless range of the AP to establish or maintain a communication link with the WLAN.

[0005] Many existing WLAN communication protocols are designed for wireless communications at carrier frequencies below 7 GHz (such as in the 2.4 GHz, 5 GHz, or 6 GHz bands). However, new WLAN communication protocols are being developed to enable enhanced WLAN communication features (such as higher throughput and wider bandwidth) that require even higher carrier frequencies (such as in the 45 GHz or 60 GHz bands). Wireless communications at higher carrier frequencies may suffer from greater phase noise and greater path loss than wireless communications at lower carrier frequencies. Therefore, new packet designs and operating modes are needed to support wireless communications at carrier frequencies above 7 GHz, as new WLAN communication protocols are able to achieve enhanced features. Summary of the invention

[0006] The systems, methods, and devices of the disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0007] An innovative aspect of the subject matter described in the present disclosure may be implemented as a method of wireless communication. The method may be performed by a wireless communication device and may include: sending a certain number (N) of beamforming training (BFT) packets in N transmit (TX) beam directions respectively on a first wireless communication link, wherein each of the N BFT packets includes a physical layer (PHY) preamble code, and the physical layer (PHY) preamble code carries corresponding beam management information indicating the TX beam direction in which the BFT packet is sent; receiving first feedback associated with a first TX beam direction among the N TX beam directions from a responding device; and sending a physical layer convergence protocol (PLCP) protocol data unit (PPDU) in the first TX beam direction on the first wireless communication link.

[0008] In some aspects, the method may further include associating with the responding device via a second wireless communication link, wherein the N BFT packets are sent over the first wireless communication link based on associating with the responding device via the second wireless communication link. In some implementations, the first wireless communication link may operate at a carrier frequency higher than 7 GHz, and the second wireless communication link may operate at a carrier frequency lower than 7 GHz.

[0009] In some implementations, each of the N BFT packets may consist only of the PHY preamble. In some implementations, the beam management information may include at least one of the following: PPDU type, training direction, beam tracking request, the number N of BFT packets, the number of BFT packets remaining to be sent, a TX sector identifier (ID) or TX antenna ID associated with the TX beam direction in which the BFT packet is sent, or the number of receive (RX) sectors or RX antennas associated with the wireless communication device. In some aspects, the first feedback may be carried in the PHY preamble of the PPDU. In some implementations, the first feedback may include the TX sector ID or the TX antenna ID indicated by the BFT packet sent in the first TX beam direction, a signal-to-noise ratio (SNR) report, or the number of RX sectors or RX antennas associated with the responding device.

[0010] In some aspects, the method may further include: retransmitting the N BFT packets in the N TX beam directions respectively on the first wireless communication link based on the number (M) of RX sectors associated with the responding device. In such aspects, each of the N BFT packets may be sent M times in the corresponding TX beam direction. In some aspects, the method may further include: receiving a certain number (K) of BFT packets on the first wireless communication link, each of the certain number (K) of BFT packets carrying beam management information indicating a corresponding beam direction associated with the received BFT packet; measuring the signal power of each of the K received BFT packets; and sending a second feedback associated with the received BFT packet having the highest signal power among the measured signal powers to the responding device. In such aspects, the first feedback may be carried in the K received BFT packets.

[0011] In some aspects, the method may further include: receiving one or more training signals on the first wireless communication link, wherein each of the one or more training signals is received via multiple antennas tuned in a corresponding RX beam direction; measuring the power of each of the one or more received training signals; and receiving a PPDU from the responding device via the multiple antennas tuned in the RX beam direction that received the training signal having the highest signal power among the measured signal powers. In some specific implementations, each of the multiple training signals may represent a corresponding PPDU. In some other specific implementations, each of the multiple training signals may represent a corresponding training (TRN) field of the same PPDU.

[0012] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a wireless communication device. In some specific implementations, the wireless communication device may include: at least one memory; and at least one processor, the at least one processor being communicatively coupled to the at least one memory and configured to cause the wireless communication device to perform operations including: sending a certain number (N) of BFT packets in N TX beam directions, respectively, each of the N BFT packets including a PHY preamble, the PHY preamble carrying corresponding beam management information indicating the TX beam direction in which the BFT packet is sent; receiving feedback associated with a first TX beam direction among the N TX beam directions from a responding device; and sending a PPDU in the first TX beam direction.

[0013] Another innovative aspect of the subject matter described in the present disclosure can be implemented as a method of wireless communication. The method can be performed by a wireless communication device and may include: receiving a certain number (N) of BFT packets on a first wireless communication link, wherein each of the N BFT packets includes a PHY preamble code, and the PHY preamble code carries beam management information indicating a corresponding beam direction associated with the received BFT packet; measuring the signal power of each BFT packet in the received BFT packets; sending a first feedback associated with the received BFT packet having the highest signal power among the measured signal powers to an initiating device; and receiving a PPDU on the first wireless communication link based on the first feedback.

[0014] In some aspects, the method may further include associating with the initiating device via a second wireless communication link, wherein the N BFT packets are received on the first wireless communication link based on associating with the initiating device via the second wireless communication link. In some implementations, the first wireless communication link may operate at a carrier frequency above 7 GHz, and the second wireless communication link may operate at a carrier frequency below 7 GHz.

[0015] In some implementations, each of the N BFT packets may consist only of the PHY preamble. In some implementations, the beam management information may include at least one of the following: PPDU type, training direction, beam tracking request, the number of BFT packets sent by the initiating device, the number of BFT packets remaining to be sent, the TX sector ID or TX antenna ID associated with the beam direction, or the number of RX sectors or RX antennas associated with the initiating device. In some aspects, the first feedback may be carried in the PHY preamble of the PPDU. In some implementations, the first feedback may include the TX sector ID or the TX antenna ID indicated by the received BFT packet with the highest signal power, an SNR report, or the number of RX sectors or RX antennas associated with the wireless communication device.

[0016] In some aspects, the N BFT packets may be received via multiple antennas tuned in a certain number (M) of RX beam directions. In some specific implementations, at least one of the N BFT packets is received multiple times based on tuning the multiple antennas in multiple RX beam directions in the M RX beam directions respectively. In some aspects, the method may also include: sending a certain number (K) of BFT packets in K TX beam directions respectively on the first wireless communication link; receiving second feedback associated with a first TX beam direction in the K TX beam directions from the initiator device; and sending a PPDU in the first TX beam direction on the first wireless communication link. In some specific implementations, the first feedback can be carried in the K sent BFT packets.

[0017] In some aspects, the method may further include: receiving one or more training signals on the first wireless communication link, wherein each of the one or more training signals is received via multiple antennas tuned in a corresponding RX beam direction; measuring the signal power of each of the one or more received training signals; and receiving a PPDU from the initiating device via the multiple antennas tuned in the RX beam direction that received the training signal having the highest signal power among the measured signal powers. In some specific implementations, each of the multiple training signals may represent a corresponding PPDU. In some other specific implementations, each of the multiple training signals may represent a corresponding TRN field of the same PPDU.

[0018] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a wireless communication device. In some specific implementations, the wireless communication device may include: at least one memory; and at least one processor, the at least one processor being communicatively coupled to the at least one memory and configured to cause the wireless communication device to perform operations including: receiving a certain number (N) of BFT packets, each of the certain number (N) of BFT packets including a PHY preamble code, the PHY preamble code carrying beam management information indicating a corresponding beam direction associated with the received BFT packet; measuring the signal power of each of the received BFT packets; sending feedback associated with the received BFT packet having the highest signal power among the measured signal powers to an initiating device; and receiving a PPDU based on the feedback. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Details of one or more specific implementations of the subject matter described in the present disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the specification, drawings, and claims. Note that the relative dimensions in the drawings may not be drawn to scale.

[0020] Figure 1 A schematic diagram of an example wireless communication network is shown.

[0021] Figure 2A Example protocol data units (PDUs) that may be used for communications between an access point (AP) and one or more wireless stations (STAs) are shown.

[0022] Figure 2B Shows Figure 2A Example fields in a PDU.

[0023] Figure 3 An example physical layer convergence protocol (PLCP) protocol data unit (PPDU) that may be used for communications between an AP and one or more STAs is shown.

[0024] Figure 4 A block diagram of an example wireless communication device is shown.

[0025] Figure 5A A block diagram of an example AP is shown.

[0026] Figure 5B A block diagram of an example STA is shown.

[0027] Figure 6 An example communication environment including an AP and a STA according to some implementations is shown.

[0028] Figure 7 An example communication system including an AP multi-link device (MLD) and a non-AP MLD is shown according to some implementations.

[0029] Figure 8 A sequence diagram depicting example multi-link communications between an AP and a STA according to some implementations is shown.

[0030] Fig.9A A timing diagram depicting an example process for training an AP and a STA to perform transmit (TX) beamforming and receive (RX) beamforming, respectively, according to some implementations is shown.

[0031] Fig. 9B A timing diagram depicting an example process for training an AP and a STA for RX beamforming and TX beamforming, respectively, according to some implementations is shown.

[0032] Fig. 10A A timing diagram depicting an example process for training APs and STAs for TX beamforming according to some implementations is shown.

[0033] Fig. 10BA timing diagram depicting an example process for training APs and STAs for RX beamforming according to some implementations is shown.

[0034] Fig. 10C Another timing diagram depicting an example process for training APs and STAs for RX beamforming according to some implementations is shown.

[0035] Fig.11 Another timing diagram depicting an example process for training APs and STAs for TX beamforming according to some implementations is shown.

[0036] Fig.12 A block diagram of an example TX processing chain for a wireless communication device is shown according to some implementations.

[0037] Fig.13A An example PPDU formatted according to the legacy PPDU format is shown.

[0038] Fig. 13B According to some specific implementations, Fig.13A An example of a PPDU format is depicted in an Upward Clocked PPDU.

[0039] Fig. 13C According to some specific implementations, Fig.13A Another example of a PPDU format is depicted in an Up-Clocked PPDU.

[0040] Fig.14A An example PPDU formatted according to the legacy PPDU format is shown.

[0041] Fig. 14B According to some specific implementations, Fig.14A An example of a PPDU format is depicted in an Upward Clocked PPDU.

[0042] Fig. 14C According to some specific implementations, Fig.14A Another example of a PPDU format is depicted in an Up-Clocked PPDU.

[0043] Fig.15A An example PPDU formatted according to the legacy PPDU format is shown.

[0044] Fig. 15B According to some specific implementations, Fig.15A An example of a PPDU format is depicted in an Upward Clocked PPDU.

[0045] Fig.16A timing diagram depicting example beamforming training operations between an AP and a STA over an anchor link and a directional link according to some implementations is shown.

[0046] Fig.17A A timing diagram depicting example beamforming training operations between an AP and a STA over an anchor link and a directional link according to some implementations is shown.

[0047] Fig. 17B Another timing diagram depicting example beamforming training operations between an AP and a STA over an anchor link and a directional link according to some implementations is shown.

[0048] Fig.18 A flow chart illustrating an example process for wireless communications supporting 60 GHz beam management for a wireless local area network (WLAN) is shown.

[0049] Fig.19 A flow chart illustrating an example process for supporting 60 GHz beam managed wireless communications for a WLAN is shown.

[0050] Fig. 20 A block diagram of an example wireless communication device is shown in accordance with some implementations.

[0051] Fig.21 A block diagram of an example wireless communication device is shown in accordance with some implementations.

[0052] The same reference numbers and designations in different drawings represent the same elements. DETAILED DESCRIPTION

[0053] The following description is directed to certain specific implementations in order to describe the innovative aspects of the present disclosure. However, one of ordinary skill in the art will readily recognize that the teachings herein can be applied in a variety of different ways. The specific implementations described may be implemented in a manner that can be implemented in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, the IEEE 802.15 standard, the Bluetooth Special Interest Group (SIG), or the like. The described implementations may be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals in accordance with one or more of the Long Term Evolution (LTE), 3G, 4G, or 5G (New Radio (NR)) standards, etc., released by the Third Generation Partnership Project (3GPP). The described implementations may be implemented in any device, system, or network capable of transmitting and receiving RF signals in accordance with one or more of the following technologies or techniques: Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Single User (SU) Multiple Input Multiple Output (MIMO), and Multi-User (MU) MIMO. The described implementations may also be implemented using other wireless communication protocols or RF signals suitable for use in one or more of a wireless personal area network (WPAN), a wireless local area network (WLAN), a wireless wide area network (WWAN), or an Internet of Things (IOT) network.

[0054] As described above, new WLAN communication protocols are being developed to implement enhanced features for wireless communications on carrier frequencies above 7 GHz (such as in the 60 GHz or 45 GHz bands). However, wireless communications on higher carrier frequencies may suffer from greater phase noise and path loss than wireless communications on lower carrier frequencies. Aspects of the present disclosure recognize that analog beamforming (using a large number of antenna elements) can mitigate the effects of path loss and achieve a greater wireless communication range on carrier frequencies above 7 GHz. Analog beamforming is a wireless communication technique by which a transmitting device and a receiving device can adjust the gain and phase of their transmit (TX) antenna elements and receive (RX) antenna elements to achieve directionality in wireless communications. For example, a transmitting device can tune a set of TX antennas to focus the energy of a transmitted signal in a particular direction (referred to as "TX beamforming"). Similarly, a receiving device can tune a set of RX antennas to focus the energy of a received signal in a particular direction (referred to as "RX beamforming"). When TX beamforming is used in combination with RX beamforming, optimal beamforming gain (such as may be required to overcome path loss in the 60 GHz band) can be achieved. The process by which the transmitting and receiving devices tune their antennas for beamforming is called "beamforming training."

[0055] Various aspects are generally related to increasing carrier frequencies for wireless communications in WLANs, and more specifically, to supporting beamforming training operations for wireless communications at carrier frequencies above 7 GHz. In some aspects, a beamforming initiator (such as an AP) may initiate a beamforming training operation on a first wireless communication link operating at a carrier frequency above 7 GHz by sending a certain number (N) of beamforming training (BFT) packets in N TX beam directions, respectively, wherein each of the N BFT packets includes a physical layer (PHY) preamble that carries corresponding beam management information indicating the TX beam direction in which the BFT packet is sent. A beamforming responder (such as a STA) receives one or more of the N BFT packets and provides feedback to the beamforming initiator indicating the TX beam direction associated with the BFT packet with the highest received signal power. In some aspects, while the beamforming initiator trains its TX antenna for TX beamforming, the beamforming responder may concurrently train its RX antenna for RX beamforming. In such aspects, the beamforming responder may tune its RX antenna in a certain number (M) of RX beam directions, and the beamforming initiator may retransmit N BFT packets each time the beamforming responder tunes its RX antenna to a new RX beam direction. In some other aspects, the beamforming responder may train its RX antenna for RX beamforming after the beamforming initiator trains its TX antenna for TX beamforming. In such aspects, when the beamforming initiator sends M training sequences respectively in the TX beam directions indicated by the feedback, the beamforming responder may tune its RX antenna in the M RX beam directions.

[0056] Specific implementations of the subject matter described in the present disclosure may be implemented to achieve one or more of the following potential advantages. By signaling beam management parameters in the PHY preamble of a BFT packet, aspects of the present disclosure may leverage existing WLAN packet formats and hardware to support wireless communications at carrier frequencies above 7 GHz. Concurrently training the TX antenna of a beamforming initiator and the RX antenna of a beamforming responder relaxes the RX sensitivity requirements at the beamforming responder (due to the combined TX beamforming gain and RX beamforming gain), but requires a large amount of training overhead (such as N×M BFT packets for training the TX antenna of the beamforming initiator and the RX antenna of the beamforming responder). In contrast, training the RX antenna of the beamforming responder separately from the TX antenna of the beamforming initiator reduces the amount of training overhead (such as N BFT packets for training the TX antenna of the beamforming initiator and M training sequences for training the RX antenna of the beamforming responder), but requires greater RX sensitivity at the beamforming responder when training the TX antenna of the beamforming initiator (due to the lack of RX beamforming).

[0057] Figure 1 A block diagram of an example wireless communication network 100 is shown. According to some aspects, the wireless communication network 100 may be an example of a wireless local area network (WLAN) such as a Wi-Fi network (and will be referred to as WLAN 100 hereinafter). For example, the WLAN 100 may be a network that implements at least one of the IEEE 802.11 family of wireless communication protocol standards, such as standards defined by the IEEE 802.11-2020 specification or revisions thereof, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be. The WLAN 100 may include numerous wireless communication devices, such as an access point (AP) 102 and a plurality of stations (STAs) 104. Although only one AP 102 is shown, the WLAN network 100 may also include a plurality of APs 102.

[0058] Each STA 104 may also be referred to as a mobile station (MS), a mobile device, a mobile handset, a wireless handset, an access terminal (AT), a user equipment (UE), a subscriber station (SS) or a subscriber unit, etc. STA 104 may represent a variety of devices, such as mobile phones, personal digital assistants (PDAs), other handheld devices, netbooks, notebook computers, tablet computers, laptops, display devices (e.g., TVs, computer monitors, navigation systems, etc.), music or other audio or stereo equipment, remote control devices (“remote controls”), printers, kitchen or other home appliances, key fobs (e.g., for passive keyless entry and start (PKES) systems), etc.

[0059] A single AP 102 and the associated set of STAs 104 may be referred to as a basic service set (BSS), which is managed by the corresponding AP 102 . Figure 1Additionally shown is an example coverage area 108 of the AP 102, which may represent a basic service area (BSA) of the WLAN 100. The BSS may be identified to users by a service set identifier (SSID) and may also be identified to other devices by a basic service set identifier (BSSID), which may be a medium access control (MAC) address of the AP 102. The AP 102 periodically broadcasts a beacon frame (“beacon”) including the BSSID to enable any STA 104 within the wireless range of the AP 102 to “associate” or reassociate with the AP 102 to establish or maintain a corresponding communication link 106 (hereinafter also referred to as a “Wi-Fi link”) with the AP 102. For example, the beacon may include an identification of a primary channel used by the corresponding AP 102 and a timing synchronization function for establishing or maintaining timing synchronization with the AP 102. The AP 102 may provide various STAs 104 in the WLAN with access to external networks via respective communication links 106 .

[0060] To establish a communication link 106 with the AP 102, each of the STAs 104 is configured to perform passive or active scanning operations ("scans") on frequency channels in one or more frequency bands (eg, 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). To perform passive scanning, the STA 104 listens for beacons transmitted by the corresponding AP 102 at periodic time intervals, referred to as target beacon transmission times (TBTTs), measured in time units (TUs), where one TU may be equal to 1024 microseconds (μs). To perform active scanning, the STA 104 generates probe requests and sequentially transmits these probe requests on each channel to be scanned, and listens for probe responses from the AP 102. Each STA 104 may be configured to identify or select an AP 102 to associate with based on the scanning information obtained through passive or active scanning, and perform authentication and association operations to establish a communication link 106 with the selected AP 102. The AP 102 assigns an association identifier (AID) to the STA 104 at the end of the association operation, and the AP 102 uses the association identifier (AID) to track the STA 104.

[0061] As wireless networks become more and more common, STA 104 may have the opportunity to select one of many BSSs within the range of the STA or to select among multiple APs 102 that together form an extended service set (ESS) (including multiple connected BSSs). Extended network stations associated with WLAN 100 may be connected to a wired or wireless distribution system that allows multiple APs 102 to be connected in such ESS. In this way, STA 104 may be covered by more than one AP 102 and may be associated with different APs 102 at different times for different transmissions. Additionally, after associating with AP 102, STA 104 may also be configured to periodically scan its surroundings to find a more appropriate AP 102 to associate with. For example, a STA 104 that is moving relative to its associated AP 102 may perform a "roaming" scan to find another AP 102 with more suitable network characteristics (such as a larger received signal strength indicator (RSSI) or a reduced traffic load).

[0062] In some cases, STA 104 may form a network without AP 102 or other equipment other than STA 104 itself. An example of such a network is a self-organizing (ad hoc) network (or wireless self-organizing network). A self-organizing network may alternatively be referred to as a mesh network or a peer-to-peer (P2P) network. In some cases, a self-organizing network may be implemented within a larger wireless network (such as WLAN 100). In such a specific implementation, although STA 104 may be able to communicate with each other through AP 102 using communication link 106, STA 104 may also communicate directly with each other via direct wireless link 110. Additionally, two STA 104 may communicate via direct communication link 110, regardless of whether the two STA 104 are associated with the same AP 102 and served by the same AP. In such a self-organizing system, one or more STA 104 may assume the role played by AP 102 in the BSS. Such STA 104 may be referred to as a group owner (GO) and may coordinate the transmission within the self-organizing network. Examples of the direct wireless link 110 include a Wi-Fi direct connection, a connection established by using a Wi-Fi Tunnel Direct Link Setup (TDLS) link, and other P2P group connections.

[0063] The AP 102 and the STA 104 may function and communicate (via corresponding communication links 106) in accordance with the IEEE 802.11 family of wireless communication protocol standards, such as those defined by the IEEE 802.11-2016 specification or its revisions, including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be. These standards define WLAN radio and baseband protocols for the PHY and medium access control (MAC) layers. The AP 102 and the STA 104 send and receive wireless communications (hereinafter also referred to as "Wi-Fi communications") to and from each other in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs). The AP 102 and STA 104 in the WLAN 100 may send PPDUs on an unlicensed spectrum, which may be a portion of a spectrum that includes frequency bands traditionally used by Wi-Fi technology, such as the 2.4 GHz band, the 5 GHz band, the 60 GHz band, the 3.6 GHz band, and the 700 MHz band. Some implementations of the AP 102 and STA 104 described herein may also communicate in other frequency bands, such as the 6 GHz band, that may support both licensed and unlicensed communications. The AP 102 and STA 104 may also be configured to communicate on other frequency bands, such as shared licensed frequency bands, where multiple operators may have licenses to operate in one or more of the same or overlapping frequency bands.

[0064] Each of the frequency bands may include multiple sub-bands or frequency channels. For example, PPDUs that comply with IEEE 802.11n, 802.11ac, 802.11ax, and 802.11be standard revisions may be sent on 2.4 GHz, 5 GHz, or 6 GHz frequency bands, where each frequency band is divided into multiple 20 MHz channels. In this way, these PPDUs are sent on a physical channel with a minimum bandwidth of 20 MHz, but larger channels may be formed through channel bonding. For example, a PPDU may be sent on a physical channel with a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels together.

[0065] Each PPDU is a composite structure including a PHY preamble and a payload in the form of a PHY service data unit (PSDU). The information provided in the preamble can be used by the receiving device to decode subsequent data in the PSDU. In an instance where the PPDU is sent on a bound channel, the preamble field can be copied and sent in each of the multiple component channels. The PHY preamble may include both a legacy part (or "legacy preamble") and a non-legacy part (or "non-legacy preamble"). Legacy preambles can be used for packet detection, automatic gain control, and channel estimation, among other purposes. Legacy preambles can also generally be used to maintain compatibility with legacy devices. The format, decoding, and information provided therein of the non-legacy part of the preamble are based on the specific IEEE 802.11 protocol to be used to send the payload.

[0066] Figure 2A An example protocol data unit (PDU) 200 that can be used for wireless communication between an AP 102 and one or more STAs 104 is shown. For example, the PDU 200 can be configured as a PPDU. As shown, the PDU 200 includes a PHY preamble 202 and a PHY payload 204. For example, the preamble 202 can include a legacy portion, which itself includes a legacy short training field (L-STF) 206 that can consist of two BPSK symbols, a legacy long training field (L-LTF) 208 that can consist of two BPSK symbols, and a legacy signal field (L-SIG) 210 that can consist of two BPSK symbols. The legacy portion of the preamble 202 can be configured according to the IEEE 802.11a wireless communication protocol standard. The preamble 202 may also include a non-legacy portion including one or more non-legacy fields 212 that comply with, for example, an IEEE wireless communication protocol such as IEEE 802.11ac, 802.11ax, 802.11be, or a later wireless communication protocol.

[0067] L-STF 206 generally enables the receiving device to perform automatic gain control (AGC) and coarse timing and frequency estimation. L-LTF 208 generally enables the receiving device to perform fine timing and frequency estimation, and can also perform initial estimation of the wireless channel. L-SIG 210 generally enables the receiving device to determine the duration of the PDU and use the determined duration to avoid sending over the PDU. For example, L-STF 206, L-LTF 208 and L-SIG 210 can be modulated according to a binary phase shift keying (BPSK) modulation scheme. Payload 204 can be modulated according to a BPSK modulation scheme, an orthogonal BPSK (Q-BPSK) modulation scheme, an orthogonal amplitude modulation (QAM) modulation scheme, or another appropriate modulation scheme. Payload 204 may include a PSDU including a data field (DATA) 214, which in turn may carry, for example, a medium access control (MAC) protocol data unit (MPDU) or higher layer data in the form of an aggregated MPDU (A-MPDU).

[0068] Figure 2B Shows Figure 2A 2. Example L-SIG 210 in PDU 200 of FIG. L-SIG 210 includes a data rate field 222, a reserved bit 224, a length field 226, a parity bit 228, and a tail field 230. Data rate field 222 indicates the data rate (note that the data rate indicated in data rate field 212 may not be the actual data rate of the data carried in payload 204). Length field 226 indicates the length of the packet, for example, in symbols or bytes. Parity bit 228 can be used to detect bit errors. Tail field 230 includes a tail bit that can be used by a receiving device to terminate the operation of a decoder (e.g., a Viterbi decoder). The receiving device can use the data rate and length indicated in data rate field 222 and length field 226 to determine the packet duration, for example, in microseconds (μs) or other time units.

[0069] Figure 3An example PPDU 300 is shown that may be used for communication between an AP 102 and one or more STAs 104. As described above, each PPDU 300 includes a PHY preamble 302 and a PSDU 304. Each PSDU 304 may represent (or "carry") one or more MAC protocol data units (MPDUs) 316. For example, each PSDU 304 may carry an aggregated MPDU (A-MPDU) 306 that includes an aggregation of multiple A-MPDU subframes 308. Each A-MPDU subframe 306 may include an MPDU frame 310 that includes a MAC delimiter 312 and a MAC header 314 preceding an accompanying MPDU 316 that includes a data portion ("payload" or "frame body") of the MPDU frame 310. Each MPDU frame 310 may also include a frame check sequence (FCS) field 318 for error detection (e.g., the FCS field may include a cyclic redundancy check (CRC)) and padding bits 320. The MPDU 316 may carry one or more MAC service data units (MSDUs) 326. For example, the MPDU 316 may carry an aggregated MSDU (A-MSDU) 322 that includes multiple A-MSDU subframes 324. Each A-MSDU subframe 324 includes a corresponding MSDU 330 preceded by a subframe header 328 and, in some cases, followed by padding bits 332.

[0070] Referring back to the MPDU frame 310, the MAC delimiter 312 may be used as a marker for the start of an associated MPDU 316 and indicates the length of the associated MPDU 316. The MAC header 314 may include a plurality of fields containing information defining or indicating the characteristics or attributes of the data encapsulated in the frame body 316. The MAC header 314 includes a duration field indicating a duration extending from the end of the PPDU to at least the end of the ACK (ACK) or block ACK (BA) of the PPDU to be sent by the receiving wireless communication device. The use of the duration field is used to reserve the wireless medium for the indicated duration and enable the receiving device to establish its network allocation vector (NAV). The MAC header 314 also includes one or more fields indicating the address of the data encapsulated in the frame body 316. For example, the MAC header 314 may include a combination of a source address, a transmitter address, a receiver address, or a destination address. The MAC header 314 may also include a frame control field containing control information. The frame control field may specify a frame type, such as a data frame, a control frame, or a management frame.

[0071] Figure 4 4 shows a block diagram of an example wireless communication device 400. In some implementations, the wireless communication device 400 may be a STA (such as a reference Figure 1 In some implementations, the wireless communication device 400 may be an example of a device in an AP (such as a STA in the STA 104 described above). Figure 1 The wireless communication device 400 is an example of a device in the described AP 102. The wireless communication device 400 is capable of sending (or outputting for sending) and receiving wireless communications (e.g., in the form of wireless packets). For example, the wireless communication device can be configured to: send and receive packets in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs) and medium access control (MAC) protocol data units (MPDUs) that comply with IEEE 802.11 wireless communication protocol standards (such as the standards defined by the IEEE 802.11-2016 specification or its revisions, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be).

[0072] The wireless communication device 400 may be or may include a chip, system on chip (SoC), chipset, package, or device that includes one or more modems 402 (e.g., Wi-Fi (IEEE 802.11 compatible) modems). In some implementations, one or more modems 402 (collectively, “modems 402”) additionally include a WWAN modem (e.g., a 3GPP 4G LTE or 5G compatible modem). In some implementations, the wireless communication device 400 also includes one or more radio components 404 (collectively, “radio components 404”). In some implementations, the wireless communication device 406 also includes one or more processors, processing blocks, or processing elements 406 (collectively, “processors 406”) and one or more memory blocks or elements 408 (collectively, “memory 408”).

[0073] The modem 402 may include an intelligent hardware block or device, such as, for example, an application specific integrated circuit (ASIC) or the like. The modem 402 is generally configured to implement the PHY layer. For example, the modem 402 is configured to modulate packets and output the modulated packets to the radio component 404 for transmission over a wireless medium. Similarly, the modem 402 is configured to obtain the modulated packets received by the radio component 404 and demodulate the packets to provide the demodulated packets. In addition to the modulator and demodulator, the modem 402 may also include a digital signal processing (DSP) circuit, an automatic gain control (AGC), a decoder, a decoder, a multiplexer, and a demultiplexer. For example, when in a transmit mode, the data obtained from the processor 406 is provided to a decoder, which encodes the data to provide the encoded bits. The encoded bits are then mapped to points in the modulation constellation (using the selected MCS) to provide the modulated symbols. The modulated symbols can then be mapped to a number N SS spatial streams or the number N STS The modulated symbols in the corresponding spatial stream or space-time stream may then be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and then provided to the DSP circuit for Tx windowing and filtering. The digital signal may then be provided to a digital-to-analog converter (DAC). The resulting analog signal may then be provided to a frequency upconverter and ultimately to the radio component 404. In a specific implementation involving beamforming, the modulated symbols in the corresponding spatial stream may be pre-coded via a steering matrix before being provided to the IFFT block.

[0074] When in receive mode, a digital signal received from the radio component 404 is provided to a DSP circuit configured to acquire the received signal, for example, by detecting the presence of a signal and estimating an initial timing and frequency offset. The DSP circuit is further configured to digitally condition the digital signal, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting I / Q imbalance), and applying digital gain to ultimately obtain a narrowband signal. The output of the DSP circuit may then be fed to an AGC configured to use information extracted from the digital signal (e.g., in one or more received training fields) to determine an appropriate gain. The output of the DSP circuit is also coupled to a demodulator configured to extract the modulated symbols from the signal and, for example, calculate a log-likelihood ratio (LLR) for each bit position of each subcarrier in each spatial stream. The demodulator is coupled to a decoder, which may be configured to process the LLRs to provide decoded bits. The decoded bits from all spatial streams are then fed to a demultiplexer for demultiplexing. The demultiplexed bits may then be descrambled and provided to the MAC layer (processor 406) for processing, evaluation, or interpretation.

[0075] The radio 404 typically includes at least one radio frequency (RF) transmitter (or "transmitter chain") and at least one RF receiver (or "receiver chain"), which may be combined into one or more transceivers. For example, the RF transmitter and receiver may include various DSP circuits, including at least one power amplifier (PA) and at least one low noise amplifier (LNA), respectively. The RF transmitter and receiver may in turn be coupled to one or more antennas. For example, in some implementations, the wireless communication device 400 may include or be coupled to multiple transmit antennas (each having a corresponding transmit chain) and multiple receive antennas (each having a corresponding receive chain). The symbols output from the modem 402 are provided to the radio 404, which then transmits the symbols via the coupled antennas. Similarly, the symbols received via the antennas are obtained by the radio 404, which then provides the symbols to the modem 402.

[0076] The processor 406 may include an intelligent hardware block or device designed to perform the functions described herein, such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD) (such as a field programmable gate array (FPGA)), a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof. The processor 406 processes information received through the radio component 404 and the modem 402, and processes information to be output by the modem 402 and the radio component 404 to be sent through the wireless medium. For example, the processor 406 can implement a control plane and a MAC layer, which is configured to perform various operations related to the generation and transmission of MPDUs, frames, or packets. The MAC layer is configured to perform or facilitate the decoding and decoding of frames, spatial multiplexing, space-time block decoding (STBC), beamforming, and OFDMA resource allocation and other operations or techniques. In some specific implementations, the processor 406 can generally control the modem 402 to cause the modem to perform the above-mentioned various operations.

[0077] The memory 408 may include a tangible storage medium, such as a random access memory (RAM) or a read-only memory (ROM) or a combination thereof. The memory 408 may also store non-transitory processor or computer executable software (SW) code containing instructions that, when executed by the processor 406, cause the processor to perform various operations described herein for wireless communication, including the generation, transmission, reception, and interpretation of MDPUs, frames, or packets. For example, various functions of the components disclosed herein or various blocks or steps of the methods, operations, processes, or algorithms disclosed herein may be implemented as one or more modules of one or more computer programs.

[0078] Figure 5A 5 shows a block diagram of an example AP 502. For example, AP 502 may be a reference Figure 1 The AP 102 is described as an example implementation. The AP 502 includes a wireless communication device (WCD) 510 (although the AP 502 itself may also be generally referred to as a wireless communication device, as used herein). For example, the wireless communication device 510 may be a wireless communication device. Figure 4 The example implementation of the wireless communication device 400 described. The AP 502 also includes a plurality of antennas 520 coupled to the wireless communication device 510 to send and receive wireless communications. In some implementations, the AP 502 additionally includes an application processor 530 coupled to the wireless communication device 510 and a memory 540 coupled to the application processor 530. The AP 502 also includes at least one external network interface 550 that enables the AP 502 to communicate with a core network or a backhaul network to gain access to an external network including the Internet. For example, the external network interface 550 may include one or both of a wired (e.g., Ethernet) network interface and a wireless network interface (such as a WWAN interface). Components of the above components may communicate directly or indirectly with other components of the components via at least one bus. The AP 502 also includes a housing that surrounds the wireless communication device 510, the application processor 530, the memory 540, and at least portions of the antennas 520 and the external network interface 550.

[0079] Figure 5B 5 shows a block diagram of an example STA 504. For example, STA 504 may be a reference Figure 1 The example implementation of STA 104 is described. STA 504 includes a wireless communication device 515 (although STA 504 itself may also be generally referred to as a wireless communication device as used herein). For example, wireless communication device 515 may be a reference Figure 4An example implementation of the wireless communication device 400 described. The STA 504 also includes one or more antennas 525 coupled to the wireless communication device 515 to send and receive wireless communications. The STA 504 additionally includes an application processor 535 coupled to the wireless communication device 515 and a memory 545 coupled to the application processor 535. In some implementations, the STA 504 also includes a user interface (UI) 555 (such as a touch screen or keyboard) and a display 565, which can be integrated with the UI 555 to form a touch screen display. In some implementations, the STA 504 may also include one or more sensors 575, such as, for example, one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors. Components of the above components can communicate directly or indirectly with other components of the components via at least one bus. The STA 504 also includes a housing that surrounds the wireless communication device 515, the application processor 535, the memory 545, and at least portions of the antenna 525, the UI 555, and the display 565.

[0080] As described above, new WLAN communication protocols are being developed to implement enhanced features for wireless communications on carrier frequencies above 7 GHz (such as in the 60 GHz or 45 GHz bands). However, wireless communications on higher carrier frequencies may suffer from greater phase noise and path loss than wireless communications on lower carrier frequencies. Aspects of the present disclosure recognize that analog beamforming (using a large number of antenna elements) can mitigate the effects of path loss and achieve a greater wireless communication range on carrier frequencies above 7 GHz. Analog beamforming is a wireless communication technique by which a transmitting device and a receiving device can adjust the gain and phase of their TX antenna elements and RX antenna elements to achieve directionality in wireless communications. For example, a transmitting device can tune a set of TX antennas to focus the energy of a transmitted signal in a particular direction (referred to as "TX beamforming"). Similarly, a receiving device can tune a set of RX antennas to focus the energy of a received signal in a particular direction (referred to as "RX beamforming"). When TX beamforming is used in combination with RX beamforming, optimal beamforming gain (such as may be required to overcome path loss in the 60 GHz band) can be achieved. The process by which the transmitting and receiving devices tune their antennas for beamforming is called "beamforming training."

[0081] Various aspects are generally related to increasing carrier frequencies for wireless communications in WLANs, and more specifically, to supporting beamforming training operations for wireless communications at carrier frequencies above 7 GHz. In some aspects, a beamforming initiator (such as an AP) may initiate a beamforming training operation on a first wireless communication link operating at a carrier frequency above 7 GHz by sending a certain number (N) of beamforming training (BFT) packets in N TX beam directions, respectively, wherein each of the N BFT packets includes a PHY preamble that carries corresponding beam management information indicating the TX beam direction in which the BFT packet is sent. A beamforming responder (such as a STA) receives one or more of the N BFT packets and provides feedback to the beamforming initiator indicating the TX beam direction associated with the BFT packet with the highest received signal power. In some aspects, while the beamforming initiator trains its TX antenna for TX beamforming, the beamforming responder may concurrently train its RX antenna for RX beamforming. In such aspects, the beamforming responder may tune its RX antenna in a certain number (M) of RX beam directions, and the beamforming initiator may retransmit N BFT packets each time the beamforming responder tunes its RX antenna to a new RX beam direction. In some other aspects, the beamforming responder may train its RX antenna for RX beamforming after the beamforming initiator trains its TX antenna for TX beamforming. In such aspects, when the beamforming initiator sends M training sequences respectively in the TX beam directions indicated by the feedback, the beamforming responder may tune its RX antenna in the M RX beam directions.

[0082] Specific implementations of the subject matter described in the present disclosure may be implemented to achieve one or more of the following potential advantages. By signaling beam management parameters in the PHY preamble of a BFT packet, aspects of the present disclosure may leverage existing WLAN packet formats and hardware to support wireless communications at carrier frequencies above 7 GHz. Concurrently training the TX antenna of a beamforming initiator and the RX antenna of a beamforming responder relaxes the RX sensitivity requirements at the beamforming responder (due to the combined TX beamforming gain and RX beamforming gain), but requires a large amount of training overhead (such as N×M BFT packets for training the TX antenna of the beamforming initiator and the RX antenna of the beamforming responder). In contrast, training the RX antenna of the beamforming responder separately from the TX antenna of the beamforming initiator reduces the amount of training overhead (such as N BFT packets for training the TX antenna of the beamforming initiator and M training sequences for training the RX antenna of the beamforming responder), but requires greater RX sensitivity at the beamforming responder when training the TX antenna of the beamforming initiator (due to the lack of RX beamforming).

[0083] Figure 6 An example communication environment 600 including an AP 610 and a STA 620 according to some implementations is shown. In some implementations, the AP 610 can be Figure 1 AP 102 or Figure 5A In some implementations, the STA 620 may be an example of any of the APs 502. Figure 1 STA 104 or Figure 5B An example of any one of STA 504. Figure 6 In the example of FIG. 6 , AP 610 is associated with a BSS that supports wireless communications at carrier frequencies above 7 GHz, such as in the 60 GHz band.

[0084] In some implementations, the AP 610 may use beamforming to communicate over greater distances and mitigate the effects of path loss at carrier frequencies above 7 GHz. For example, the AP 610 may transmit packets or PPDUs via a number of antenna sectors T1-T7 (also referred to as "TX sectors") that are configured or tuned for TX beamforming. The antenna elements associated with each TX sector are weighted so that the energy radiated by each antenna element combines along a particular beam direction. Thus, each of the TX sectors T1-T7 may be tuned to a corresponding TX beam direction. For simplicity, the AP 610 is shown as including 7 TX sectors T1-T7. However, in actual implementations, the AP 610 may include more than 10 TX sectors. Figure 6 Those APs depicted in FIG. 5 may have fewer or more TX sectors.

[0085] In some implementations, STA 620 may also use beamforming to communicate on carrier frequencies above 7 GHz. For example, STA 620 may receive packets or PPDUs via a number of antenna sectors R1-R7 (also referred to as "RX sectors") configured or tuned for RX beamforming. The antenna elements associated with each RX sector are weighted so that the energy received by each antenna element is combined along a specific beam direction. Therefore, each of the RX sectors R1-R7 may be tuned to a corresponding RX beam direction. For simplicity, STA 620 is shown as including 7 RX sectors R1-R7. However, in actual implementations, STA 620 may include more than 10 RX sectors. Figure 6 Those APs depicted in FIG. 5 may have fewer or more RX sectors.

[0086] In some aspects, the AP 610 may perform a beamforming training operation with the STA 620 to determine a TX beam direction and an RX beam direction that optimizes a beamforming gain for wireless communications between the AP 610 and the STA 620. For example, the AP 610 may train its TX antenna for TX beamforming by sending a respective beamforming training (BFT) packet via each of the TX sectors T1-T7 and receiving feedback from the STA 620 indicating the TX sector associated with the highest TX beamforming gain. In addition, the STA 620 may train its RX antenna for RX beamforming by listening to a respective BFT packet from the AP 610 via each of the RX sectors R1-R7 and determining the RX sector associated with the highest RX beamforming gain based on the received BFT packet. In some implementations, the AP 610 may further train its RX antenna (not shown for simplicity) for RX beamforming, and the STA 620 may further train its TX antenna (not shown for simplicity) for TX beamforming.

[0087] Although beamforming can help mitigate path loss at carrier frequencies above 7 GHz, the directionality of the beamformed signal (or "beam") presents challenges for BSS discovery and association. Figure 6 As shown, the AP 610 and the STA 620 may achieve optimized beamforming gains for beams transmitted via TX sector T1 (of the AP 610) and beams received via RX sector R7 (of the STA 620). In contrast, beams transmitted by the AP 610 in other TX beam directions (such as via any of TX sectors T2-T7) may fail to reach the STA 620. During BSS discovery and association operations that rely on packet exchange between the AP 610 and the STA 620, the AP 610 is generally unaware of the direction of the STA 620. In some aspects, the AP 610 may transmit a beam in each of the AP's TX beam directions prior to performing beamforming training operations, such that at least one of the beams reaches the STA 620. In some implementations, such beams may carry management or control information that may be used to establish or maintain communications with the STA 620 (such as for BSS discovery or association).

[0088] Repeatedly sending the same management or control frame via each of TX sectors T1-T7 may consume a large amount of overhead and may result in inefficient use of the wireless medium. Existing versions of the IEEE 802.11 standard define a BSS discovery protocol for carrier frequencies below 7 GHz (also referred to as the "sub-7 GHz" band), whereby an AP announces the BSS of the AP in management frames (such as beacons or probe responses) sent omnidirectionally. Any STA within the coverage area of ​​the AP may receive such management frames and request to associate with (or maintain association with) the BSS. Therefore, aspects of the present disclosure recognize that BSS discovery and association operations may be performed more efficiently in the sub-7 GHz band than at carrier frequencies above 7 GHz.

[0089] Aspects of the present disclosure further recognize that some wireless communication devices (including APs and STAs) are capable of multi-link operation (MLO). Devices with MLO capabilities may be referred to as multi-link devices (MLDs). For example, an AP MLD may include multiple APs, each of which is configured to communicate with a non-AP MLD (also referred to as a "STA MLD") on a corresponding communication link. Similarly, a non-AP MLD may include multiple STAs, each of which is configured to communicate with the AP MLD on a corresponding one of the communication links. In some specific implementations, the AP 610 and the STA 620 may utilize multiple wireless communication links to support wireless communication at carrier frequencies above 7 GHz. More specifically, the AP 610 and the STA 620 may perform at least some management and control functions (such as BSS discovery or association) via omnidirectional communication on a wireless communication link operating at a carrier frequency below 7 GHz, and may communicate via directional beams on a wireless communication link operating at a carrier frequency above 7 GHz.

[0090] Figure 7 FIG. 7 shows an example communication system 700 including an AP MLD 710 and a non-AP MLD 720 according to some implementations. In some implementations, the AP MLD 710 may be a Figure 1 AP 102 Figure 5A AP 502 or Figure 6 In some implementations, the non-AP MLD 720 may be an example of any of the APs 610. Figure 1 STA 104 Figure 5B STA 504 or Figure 6 An example of any one of STA 620.

[0091] AP MLD 710 includes a plurality of APs 712 and 714 associated with (or operating on) communication links 702 and 704, respectively. Figure 7 In the example of FIG. 7 , the AP MLD 710 is shown as including two APs. However, in some implementations, the AP MLD 710 may include more than Figure 7 . In some aspects, APs 712 and 714 may share a common association context (via AP MLD 710). APs 712 and 714 may also establish their respective communication links 702 and 704 on different frequency bands. In some implementations, AP 712 may operate at a carrier frequency below 7 GHz (such as in any of the 2.4 GHz, 5 GHz, or 6 GHz bands), and AP 714 may operate at a carrier frequency above 7 GHz (such as in the 60 GHz or 45 GHz bands).

[0092] The non-AP MLD 720 includes a plurality of STAs 722 and 724 that can be configured to communicate on communication links 702 and 704, respectively. In some implementations, the STA 722 can operate at a carrier frequency below 7 GHz (such as in any of the 2.4 GHz, 5 GHz, or 6 GHz bands), and the STA 724 can operate at a carrier frequency above 7 GHz (such as in the 60 GHz or 45 GHz bands). Figure 7 In the example of FIG. 7 , the non-AP MLD 720 is shown as including two STAs. However, in some implementations, the non-AP MLD 720 may include more than Figure 7 The existing versions of the IEEE 802.11 standard define several modes in which the non-AP MLD can operate. The various operating modes depend on the number of wireless radio components associated with the non-AP MLD and the ability of the non-AP MLD to communicate concurrently on multiple communication links (such as by sending or receiving).

[0093] In some implementations, the non-AP MLD 720 may include a single radio or may otherwise be capable of communicating on only one link at a time. In such implementations, the non-AP MLD 720 may operate in a multi-link single radio (MLSR) mode or an enhanced MLSR (eMLSR) mode. A non-AP MLD operating in the eMLSR mode may concurrently listen to packets of a particular type (such as a buffer status report poll (BSRP) frame or a multi-user request to transmit (MU-RTS) frame) on multiple links, but may only transmit or receive on one of the links at any given time. For example, STAs 722 and 724 may concurrently listen to their respective links 702 and 704 during a listening interval. However, if either STA 722 or 724 detects a BSRP frame on its respective link, the non-AP MLD 720 then tunes all of its antennas to the link on which the BSRP frame was detected. In contrast, a non-AP MLD operating in the MLSR mode may only listen to one communication link and may only transmit or receive on one communication link at any given time. For example, one of STA 722 or 724 must be in power save mode any time the other STA is active.

[0094] In some other implementations, the non-AP MLD 720 may include multiple radio components and may be capable of concurrent communication on each of the links 702 and 704. In such implementations, the non-AP MLD 720 may operate in a multi-link multi-radio component (MLMR) simultaneous transmit and receive (STR) mode or a multi-link multi-radio component non-STR (NSTR) mode. A non-AP MLD operating in the MLMR STR mode may transmit and receive on multiple links simultaneously. For example, STA 722 may transmit or receive on link 702 while STA 724 concurrently transmits or receives on link 704. More specifically, such communications may be asynchronous. In other words, STA 722 may be transmitting on link 702 while STA 724 is receiving on link 704. In contrast, a non-AP MLD operating in the MLMR NSTR mode may transmit and receive on multiple links simultaneously, provided that such communications are synchronous. For example, STA 722 and 724 may transmit concurrently on links 702 and 704, and may also receive concurrently on links 702 and 704. However, STA 722 may not transmit on link 702 while STA 724 is receiving on link 704.

[0095] Furthermore, in some implementations, a non-AP MLD may include multiple radio components, but may only be able to communicate concurrently on a subset of links. In such implementations, the non-AP MLD 720 may operate in an enhanced MLMR (eMLMR) mode or a hybrid eMLMR mode. A non-AP MLD operating in the eMLMR mode only supports MLMRSTR operations between some link pairs. For example, STAs 722 and 724 may communicate concurrently on their respective links 502 and 504 according to the MLMR STR operation mode, while other STA pairs associated with the non-AP MLD 720 (not shown for simplicity) may not transmit or receive concurrently on their respective links (referred to herein as "eMLMR links"). Therefore, such other STAs may "pool" their antennas so that each of the STAs may utilize the antennas of other STAs when transmitting or receiving on one of the eMLMR links. On the other hand, a non-AP MLD operating in the hybrid eMLSR mode supports MLMR STR operations between some link pairs and eMLSR operations between some other link pairs.

[0096] In some aspects, the AP MLD 710 and the non-AP MLD 720 may perform various management and control functions (such as BSS discovery or association) on the link 702, and may exchange directional communications on the link 704 based on the management and control functions performed on the link 702. As such, the link 704 may be referred to as a "directional link," and the link 702 may be referred to as an "anchor link" associated with the directional link. In some implementations, the AP MLD 720 may announce the BSS of the AP in a management frame (such as a beacon or a probe response) sent omnidirectionally on the anchor link 702. The AP MLD 710 may further associate with the non-AP MLD 720 through the anchor link 702 based on the BSS information carried in the beacon or the probe response. In some implementations, the AP MLD 710 may communicate with the non-AP MLD 720 on the directional link 704 based on the association context established on the anchor link 702. More specifically, the AP MLD 710 and the non-AP MLD 720 may use (such as reference Figure 6 ) beamforming techniques described herein are used to communicate over directional link 704.

[0097] Figure 8 A sequence diagram 800 depicting an example multi-link communication between an AP 810 and a STA 820 according to some implementations is shown. In some implementations, the AP 810 and the STA 820 may be respectively Figure 7802 and 804. Figure 7 , communication links 802 and 804 may be examples of communication links 702 and 704, respectively. As such, link 802 may be an anchor link operating at a carrier frequency below 7 GHz, and link 804 may be a directional link operating at a carrier frequency above 7 GHz.

[0098] exist Figure 8 In the example of , AP 810 and STA 820 are initially in an unassociated state. Therefore, AP 810 and STA 820 may perform BSS discovery over anchor link 802. For example, the AP may send a management frame (such as a beacon or a probe response) carrying BSS information announcing the BSS of the AP over anchor link 802. Such management frames may be sent omnidirectionally so that any STA within the coverage area of ​​AP 810 may discover the BSS. Upon discovering the BSS, STA 820 may request to associate with AP 810. Therefore, AP 810 and STA 820 may perform an association operation over anchor link 802. For example, STA 820 may first initiate a low-level authentication exchange with AP 810 over anchor link 802. After authentication, STA 820 may send an association request to AP 810 over anchor link 802. AP 810 may complete the association operation by sending an association response back to STA 820 via anchor link 802.

[0099] Once associated, the AP 810 may communicate with the STA 820 via the directional link 804. In this way, wireless communications on the directional link 804 (such as for data transmission) are effectively coupled to wireless communications on the anchor link 802 (such as for BSS discovery and association). In some implementations, the STA 820 (and the AP 810) may use a reference Figure 7 Any of the described techniques switches between the anchor link 802 and the directional link 804. In some aspects, when communicating on the directional link 804, the AP 810 and the STA 820 may use beamforming techniques, for example, to mitigate the effects of path loss at carrier frequencies above 7 GHz. Figure 6 As described, AP 810 may perform a beamforming training operation with STA 820 to determine a TX beam direction and an RX beam direction that optimizes a beamforming gain.

[0100] In some implementations, the AP 810 may initiate a beamforming training operation by sending a corresponding BFT packet over the directional link 804 via each of its TX sectors, and the STA 820 may provide feedback to the AP 810 in response to receiving one or more of the BFT packets. For example, the feedback may indicate which of the BFT packets sent by the AP 810 (or which of the TX sectors of the AP 810) is associated with the highest received signal power. In some other implementations, the STA 820 may initiate a beamforming training operation by sending a corresponding BFT packet over the directional link 804 via each of its TX sectors, and the AP 810 may provide feedback to the STA 820 in response to receiving one or more of the BFT packets. For example, the feedback may indicate which of the BFT packets sent by the STA 820 (or which of the TX sectors of the STA 820) is associated with the highest received signal power. A device that initiates a beamforming training operation is referred to as a "beamforming initiator." In contrast, a device that responds to (or provides feedback to) a beamforming initiator is referred to as a "beamforming responder."

[0101] As a result of the beamforming training operation, the beamforming initiator selects a TX beam direction to be used for directional communication with the beamforming responder, and the beamforming responder selects an RX beam direction to be used for directional communication with the beamforming initiator. In some implementations, the beamforming initiator may also select an RX beam direction to be used for directional communication with the beamforming responder, and the beamforming responder may also select a TX beam direction to be used for directional communication with the beamforming initiator. Thus, the AP 810 may communicate with the STA 820 over the directional link 804 using a beam associated with the TX beam direction and the RX beam direction determined as a result of the beamforming training operation. In some implementations, the AP 810 may further refine the TX beam direction or the RX beam direction of the AP based on real-time communication with the STA 820. In some implementations, the STA 820 may further refine the TX beam direction or the RX beam direction of the STA based on real-time communication with the AP 810.

[0102] Fig.9A A timing diagram 900 is shown depicting an example process for training an AP and a STA, respectively, for TX beamforming and RX beamforming according to some implementations. In some aspects, Fig.9A The training process of may represent at least a portion of a beamforming training operation that may be performed on a carrier frequency above 7 GHz (such as a directional link). In some implementations, the APs may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7 In some implementations, the STAs may be respectively Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 An example of a non-AP MLD 720 .

[0103] exist Fig.9A In the example of , while the STA is training its RX antenna for RX beamforming, the AP concurrently trains its TX antenna for TX beamforming. More specifically, the training process is performed over a certain number (M) of beam training intervals 902(1)-902(M) that is equal to the number of RX sectors associated with the STA. During each beam training interval 902, the AP sends a certain number (N) of BFT packets in N TX beam directions (T1-TN), respectively, and the STA attempts to receive (or listen to) the N BFT packets by tuning its RX antenna to a specific RX beam direction. More specifically, the RX antenna associated with the STA is tuned to M RX beam directions (R1-RM) over the M training intervals 902(1)-902(M), respectively, and remains tuned to the same RX beam direction during the duration of each beam training interval 902. Each of the TX beam directions may be aligned with a corresponding TX sector of the AP (such as Figure 6 TX sectors T1-T7 of the STA), and each of the RX beam directions may be associated with a corresponding RX sector of the STA (such as Figure 6 The RX sectors R1-R7) are associated with each other.

[0104] The first beam training interval 902(1) occurs between time t0 and t1. During the first beam training interval 902(1), the AP performs a TX sector sweep while the STA listens in the R1 beam direction. More specifically, the AP sends N BFT packets in the T1-TN beam directions, respectively, and the STA attempts to receive each of the N BFT packets via the RX sector associated with the R1 beam direction. In some implementations, each of the N BFT packets may carry beam management information that may be used to train a TX sector or RX sector of the AP. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (N), sector identifier (ID), antenna ID, or number of RX antennas or sectors associated with the AP, etc. Due to various pairings of R1 beam direction and T1-TN beam direction, the STA may receive zero or more of the BFT packets sent by the AP between time t0 and t1. In some implementations, the STA may measure the signal power of each of the received BFT packets (if any) during the first beam training interval 902(1).

[0105] The second beam training interval 902(2) occurs between time t1 and t2. During the second beam training interval 902(2), the AP performs a TX sector sweep while the STA listens in the R2 beam direction. More specifically, the AP sends N BFT packets in the T1-TN beam directions, respectively, and the STA attempts to receive each of the N BFT packets via the RX sector associated with the R2 beam direction. In some implementations, each of the N BFT packets may carry beam management information that may be used to train a TX sector or RX sector of the AP. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (N), sector ID, antenna ID, or number of RX antennas or sectors associated with the AP, etc. Due to various pairings of the R2 beam direction and the T1-TN beam direction, the STA may receive zero or more of the BFT packets sent by the AP between time t1 and t2. In some implementations, the STA may measure the signal power of each of the received BFT packets (if any) during the second beam training interval 902(2).

[0106] The Mth beam training interval 902(M) occurs between time t3 and t4. During the Mth beam training interval 902(M), the AP performs a TX sector sweep while the STA listens in the RM beam direction. More specifically, the AP sends N BFT packets in the T1-TN beam directions, respectively, and the STA attempts to receive each of the N BFT packets via the RX sector associated with the RM beam direction. In some implementations, each of the N BFT packets may carry beam management information that may be used to train a TX sector or RX sector of the AP. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (N), sector ID, antenna ID, or number of RX antennas or sectors associated with the AP, etc. Due to various pairings of RM beam directions and T1-TN beam directions, the STA may receive zero or more of the BFT packets sent by the AP between time t3 and t4. In some implementations, the STA may measure the signal power of each of the received BFT packets (if any) during the Mth beam training interval 902 (M).

[0107] The STA compares the measured signal powers of the received BFT packets across the beam training intervals 902(1)-902(M) and selects the combination of the TX beam direction and the RX beam direction that produces the highest measured signal power. The selected TX beam direction may be referred to herein as the "best TX beam direction" and the selected RX beam direction may be referred to herein as the "best RX beam direction". At time t5, the STA provides feedback (FB) to the AP indicating the best TX beam direction. For example, the feedback may include a best sector ID (such as the sector ID of the AP associated with the best TX beam direction), a best antenna ID (such as the antenna ID of the AP associated with the best TX beam direction), or a signal-to-noise ratio (SNR) report, etc. Thereafter, the AP may tune its TX antenna in the best TX beam direction and the STA may tune its RX antenna in the best RX beam direction to exchange directional communications over a directional link.

[0108] In some implementations, the AP and STA may support antenna reciprocity. In other words, for a given wireless communication device, the sector ID (or antenna ID) associated with the best TX beam direction is the same as the sector ID (or antenna ID) associated with the best RX beam direction. In such implementations, the beamforming training operation may terminate after the STA provides feedback to the AP at time t5. In some other implementations, at least one of the AP or the STA may not support antenna reciprocity. In other words, for a given wireless communication device, the sector ID (or antenna ID) associated with the best TX beam direction may be different from the sector ID (or antenna ID) associated with the best RX beam direction. In such implementations, the AP and the STA must perform additional training to determine the best RX beam direction for the AP and the best TX beam direction for the STA.

[0109] Fig. 9B A timing diagram 910 is shown depicting an example process for training an AP and a STA to perform TX beamforming and RX beamforming, respectively, according to some implementations. In some aspects, Fig. 9B The training process of may represent at least a portion of a beamforming training operation that may be performed on a carrier frequency above 7 GHz (such as a directional link). In some implementations, Fig. 9B The training process can be Fig.9A After a training process of (where at least one of the AP or STA does not support antenna reciprocity). In some implementations, the AP may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7 In some implementations, the STAs may be Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 An example of a non-AP MLD 720 is shown.

[0110] exist Fig. 9BIn the example of , while the STA trains its TX antenna for TX beamforming, the AP concurrently trains its RX antenna for RX beamforming. More specifically, the training process is performed over a certain number (N) of beam training intervals 912(1)-912(N) equal to the number of RX sectors associated with the AP. During each beam training interval 912, the STA sends a certain number (M) of BFT packets in M ​​TX beam directions (T1-TM), respectively, and the AP attempts to receive (or listen to) the M BFT packets by tuning its RX antenna to a specific RX beam direction. More specifically, the RX antenna associated with the AP is tuned to N RX beam directions (R1-RN) over N training intervals 912(1)-912(N), respectively, and remains tuned to the same RX beam direction during the duration of each beam training interval 912. Each of the TX beam directions may be associated with a corresponding TX sector of the STA, and each of the RX beam directions may be associated with a corresponding RX sector of the AP.

[0111] The first beam training interval 912(1) occurs between time t6 and t7. During the first beam training interval 912(1), the STA performs a TX sector sweep while the AP listens in the R1 beam direction. More specifically, the STA sends M BFT packets in the T1-TM beam directions, respectively, and the AP attempts to receive each of the M BFT packets via the RX sector associated with the R1 beam direction. In some implementations, each of the M BFT packets may carry beam management information for a TX sector or RX sector that may be used to train the STA. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (M), sector ID, antenna ID, or number of RX antennas or sectors associated with the STA, etc. Due to various pairings of R1 beam directions and T1-TM beam directions, the AP may receive zero or more of the BFT packets sent by the STA between time t6 and t7. In some implementations, the AP may measure the signal power of each of the received BFT packets (if any) during the first beam training interval 912(1).

[0112] The second beam training interval 912(2) occurs between time t7 and t8. During the second beam training interval 912(2), the STA performs a TX sector sweep while the AP listens in the R2 beam direction. More specifically, the STA sends M BFT packets in the T1-TM beam directions, respectively, and the AP attempts to receive each of the M BFT packets via the RX sector associated with the R2 beam direction. In some implementations, each of the M BFT packets may carry beam management information for a TX sector or RX sector that may be used to train the STA. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (M), sector ID, antenna ID, or number of RX antennas or sectors associated with the STA, etc. Due to various pairings of R2 beam directions and T1-TM beam directions, the AP may receive zero or more of the BFT packets sent by the STA between time t7 and t8. In some implementations, the AP may measure the signal power of each of the received BFT packets (if any) during the second beam training interval 912(2).

[0113] The Nth beam training interval 912 (N) occurs at time t9 and t 10 During the Nth beam training interval 912 (N), the STA performs a TX sector sweep while the AP listens in the RN beam direction. More specifically, the STA sends M BFT packets in the T1-TM beam directions, respectively, and the AP attempts to receive each of the M BFTs via the RX sector associated with the RN beam direction. In some implementations, each of the M BFT packets may carry beam management information that can be used to train the TX sector or RX sector of the STA. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (M), sector ID, antenna ID, or number of RX antennas or sectors associated with the STA, etc. Due to various pairings of RN beam directions and T1-TM beam directions, the AP may be able to receive the RN beam direction at time t9 and t1-TM beam direction at time t1-TM. 10 In some implementations, the AP may measure the signal power of each of the received BFT packets (if any) during the Nth beam training interval 912(N).

[0114] The AP compares the measured signal powers of the received BFT packets across the beam training intervals 912(1)-912(N) and selects the best TX beam direction and the best RX beam direction (such as the TX beam direction and RX beam direction that produce the highest measured signal power).11 At , the AP provides feedback (FB) indicating the best TX beam direction to the STA. For example, the feedback may include the best sector ID (such as the sector ID of the STA associated with the best TX beam direction), the best antenna ID (such as the antenna ID of the STA associated with the best TX beam direction), or an SNR report, etc. Thereafter, the STA may tune its TX antenna in the best TX beam direction and the AP may tune its RX antenna in the best RX beam direction to exchange directional communications through the directional link.

[0115] Fig. 10A A timing diagram 1000 is shown depicting an example process for training an AP and a STA to perform TX beamforming according to some implementations. In some aspects, Fig. 10A The training process of may represent at least a portion of a beamforming training operation that may be performed on a carrier frequency above 7 GHz (such as a directional link). In some implementations, the APs may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7 In some implementations, the STAs may be respectively Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 An example of a non-AP MLD 720 is shown.

[0116] The AP performs a TX sector sweep between time t0 and t1 while the STA listens in omni-directional mode. More specifically, the AP sends a certain number (N) of BFT packets on N TX beam directions (T1-TN), respectively, and the STA receives one or more of the N BFT packets without tuning its RX antenna for RX beamforming. Each of the T1-TN beam directions may be associated with a corresponding TX sector of the AP. In some implementations, each of the N BFT packets may carry beam management information that may be used to train a TX sector or RX sector of the AP. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (N), number of remaining BFT packets to be sent (K), sector ID, antenna ID, or number of RX antennas or sectors associated with the AP, etc. The STA measures the signal power of each of the BFT packets received from the AP and selects the best TX beam direction associated with the signal power (such as the TX beam direction that produces the highest measured signal power).

[0117] When the AP listens in omni-directional mode, the STA performs a TX sector sweep between time t1 and t2. More specifically, the STA sends a certain number (M) of BFT packets on M TX beam directions (T1-TM), respectively, and the AP receives one or more of the M BFT packets without tuning its RX antenna for RX beamforming. Each of the T1-TM beam directions may be associated with a corresponding TX sector of the STA. In some implementations, each of the M BFT packets may carry beam management information that can be used to train the TX sector or RX sector of the STA. In some implementations, the beam management information may also indicate the best TX beam direction associated with the BFT packet sent by the AP between time t0 and t1. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (M), number of remaining BFT packets to be sent (L), sector ID, antenna ID, best sector ID, best antenna ID, SNR report, or the number of RX antennas or sectors associated with the STA, etc.

[0118] The AP measures the signal power of each of the BFT packets received from the STA between time t1 and t2, and selects the best TX beam direction associated with the signal power (such as the TX beam direction that produces the highest measured signal power). At time t3, the AP provides feedback (FB) to the STA indicating the best TX beam direction associated with the BFT packet sent by the STA between time t1 and t2. For example, the feedback may include the best sector ID, the best antenna ID, or the SNR report, etc. Thereafter, the AP may tune the TX antenna of the AP in the best TX beam direction indicated by the STA (such as via the BFT packet sent between time t1 and t2) to send a beam to the STA on a directional link. Similarly, the STA may tune the TX antenna of the STA in the best TX beam direction indicated by the AP (such as via the feedback provided at time t3) to send a beam to the AP on a directional link.

[0119] In some implementations, the AP and the STA may support antenna reciprocity (where the best TX beam direction is the same as the best RX beam direction for a given wireless communication device). In such implementations, the beamforming training operation may terminate after the AP provides feedback to the STA at time t3. In some other implementations, at least one of the AP or the STA may not support antenna reciprocity (where the best TX beam direction may be different from the best RX beam direction for a given wireless communication device). In such implementations, the AP and the STA must perform additional training to determine the best RX beam direction for the AP and the best RX beam direction for the STA.

[0120] Fig. 10B A timing diagram 1010 depicting an example process for training an AP and a STA to perform RX beamforming according to some implementations is shown. In some aspects, Fig. 10B The training process of may represent at least a portion of a beamforming training operation that may be performed on a carrier frequency above 7 GHz (such as a directional link). In some implementations, Fig. 10B The training process can be Fig. 10A After a training process of (where at least one of the AP or STA does not support antenna reciprocity). In some implementations, the AP may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7 In some implementations, the STAs may be respectively Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 An example of a non-AP MLD 720 is shown.

[0121] The AP performs RX sector sweeping between times t4 and t5 while the STA is in the best TX beam direction (TS) associated with the STA (such as that indicated by Fig. 10A A certain number (N) of training signals are sent in the optimal TX beam direction indicated by the feedback at time t3. Fig. 10B In the example of FIG. 1 , each of the N training signals is sent as a corresponding BFT packet (or PPDU). More specifically, the STA sends N BFT packets in the TS beam direction, and the AP attempts to receive the N BFT packets by tuning its RX antenna in the N RX beam directions (R1-RN), respectively. For example, each of the R1-RN beam directions can be associated with a corresponding RX sector of the AP. In some implementations, each of the N BFT packets can carry beam management information (such as reference Fig. 10A The AP measures the signal power of each received BFT packet and selects the best RX beam direction associated with the signal power (such as the RX beam direction that produces the highest measured signal power).

[0122] The STA performs RX sector sweeping between times t5 and t6 while the AP is in the best TX beam direction (TA) associated with the AP (such as indicated by Fig. 10A A certain number (M) of training signals are sent in the best TX beam direction indicated by the BFT group between time t1 and t2. Fig. 10BIn the example of , each of the M training signals is sent as a corresponding BFT packet (or PPDU). More specifically, the AP sends M BFT packets in the TA beam direction, and the STA attempts to receive the M BFT packets by tuning its RX antenna in the M RX beam directions (R1-RM), respectively. For example, each of the R1-RM beam directions can be associated with a corresponding RX sector of the STA. In some implementations, each of the M BFT packets can carry beam management information (such as reference Fig. 10A The STA measures the signal power of each received BFT packet and selects the best RX beam direction associated with the signal power (such as the RX beam direction that produces the highest measured signal power).

[0123] After time t6, the AP may tune the RX antenna of the AP in the best RX beam direction determined as a result of its RX sector sweep (between time t4 and t5) to receive the beam sent by the STA on the directional link. Similarly, the STA may tune the RX antenna of the STA in the best RX beam direction determined as a result of its RX sector sweep (between time t5 and t6) to receive the beam sent by the AP on the directional link. In some aspects, the training signals for training the RX antennas of the AP and STA may be combined into a single packet or PPDU. For example, each training signal may be sent as a corresponding training field (TRN) of the same PPDU. In some specific implementations, such a PPDU may also carry data intended for the AP or STA. The process of using TRNs to train the TX antenna or RX antenna of a wireless communication device for beamforming is referred to herein as "beam refinement".

[0124] Fig. 10C Another timing diagram 1020 is shown depicting an example process for training APs and STAs for RX beamforming according to some implementations. In some aspects, Fig. 10C The training process of may represent at least a portion of a beamforming training operation that may be performed on a carrier frequency above 7 GHz (such as a directional link). In some implementations, Fig. 10C The training process can be Fig. 10A After a training process of (where at least one of the AP or STA does not support antenna reciprocity). In some implementations, the AP may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7 In some implementations, the STAs may be respectively Figure 6 STA 620 or Figure 8Any of the STA 820 or Figure 7 An example of a non-AP MLD 720 is shown.

[0125] The AP performs RX beam refinement between time t4 and t5 while the STA is in the best TX beam direction (TS) associated with the STA (such as that determined by Fig. 10A A series of training signals are sent in the optimal TX beam direction indicated by the feedback at time t3. Fig. 10C In the example of FIG. 1 , each of the training signals is sent as a corresponding training field (TRN) of the PPDU. In other words, the series of training signals share the same PHY preamble (PRE). In some implementations, the STA may send a certain number (N) of TRNs in the TS beam direction, and the AP attempts to receive the N TRNs by tuning its RX antenna in N RX beam directions (R1-RN), respectively, where each of the R1-RN beam directions is associated with a corresponding RX sector of the AP (such as Fig. 10C ). In some other implementations, the STA may transmit a number (K) of TRNs in the TS beam direction while the AP attempts to receive each of the K TRNs via a corresponding antenna element (listening in omni-directional mode). In some aspects, the PPDU may carry beam management information associated with the N TRNs (such as reference Fig. 10A In some implementations, the AP may measure the signal power of each received TRN and may select the best RX beam direction associated with the signal power (such as the RX beam direction associated with the RX sector or antenna element that produces the highest measured signal power).

[0126] The STA performs RX beam refinement between times t5 and t6 while the AP is in the best TX beam direction (TA) associated with the AP (such as that determined by Fig. 10A A series of training signals are sent in the optimal TX beam direction indicated by the BFT packet between time t1 and t2. Fig. 10C In the example of , each training signal in the training signal is sent as a corresponding TRN of the PPDU. In other words, the series of training signals share the same PHY preamble. In some implementations, the AP may send a certain number (M) of TRNs in the TA beam direction, and the STA attempts to receive the M TRNs by tuning its RX antenna in the M RX beam directions (R1-RM), respectively, where each of the R1-RM beam directions is associated with a corresponding RX sector of the STA (such as Fig. 10C). In some other implementations, the AP may send a number (L) of TRNs in the TA beam direction, and the STA attempts to receive each of the L TRNs via the corresponding antenna element (listening in omni-directional mode). In some aspects, the PPDU may carry beam management information associated with the M TRNs (such as reference Fig. 10A In some implementations, the STA may measure the signal power of each received TRN and may select the best RX beam direction associated with the signal power (such as the RX beam direction associated with the RX sector or antenna element that produces the highest measured signal power).

[0127] After time t6, the AP may tune its RX antenna in the best RX beam direction determined as a result of its RX beam refinement (between time t4 and t5) to receive the beam sent by the STA on the directional link. Similarly, the STA may tune its RX antenna in the best RX beam direction determined as a result of its RX beam refinement (between time t5 and t6) to receive the beam sent by the AP on the directional link. In some implementations, the beam refinement protocol may be used in conjunction with data communications. In such implementations, the TRN may be appended to the end of the PPDU that includes the data portion. For example, referring to Fig. 10C , a PPDU sent by a STA (between time t4 and t5) may include a data portion (between the PHY preamble and the TRN) carrying data intended for the AP. Similarly, a PPDU sent by an AP (between time t5 and t6) may include a data portion (between the PHY preamble and the TRN) carrying data intended for the STA.

[0128] Aspects of the present disclosure recognize that the AP and STA may need to perform multiple beamforming training operations over time to maintain communication over a wireless communication link. For example, if a directional link is interrupted or if a STA reassociates with an AP, the AP and STA may need to retrain their TX antennas and RX antennas. In addition, the optimal TX beam direction or RX beam direction may change due to movement of the STA (or AP) or changes in channel conditions (or other environmental factors). In some aspects, the AP and STA may periodically perform subsequent beamforming training operations to retrain their TX antennas or RX antennas. In some other aspects, if the link quality metric drops below a threshold level, the AP and STA may perform subsequent beamforming training operations. In some specific implementations, each subsequent beamforming training operation may include a full scan of all TX beam directions and RX beam directions associated with the AP and STA. In some other embodiments, each subsequent beamforming training operation (after the initial beamforming training operation) may include only a partial scan of the TX beam directions and RX beam directions associated with the AP and STAs (such as a subset of TX beam directions or RX beam directions centered around the best TX beam direction or RX beam direction from the previous scan).

[0129] In some implementations, the AP and STA may retrain their TX antennas (such as reference 1) by performing a TX sector sweep. Fig.9A , Fig. 9B and Fig. 10A In some implementations, the AP and STA may retrain their RX antennas by performing RX sector sweeps (such as described in reference to Fig.9A , Fig. 9B and Fig. 10B In some other implementations, the AP and STA may use a beam refinement protocol to retrain their RX antennas (such as described in reference Fig. 10C In addition, in some implementations, the AP and STAs may use a beam refinement protocol to retrain their TX antennas.

[0130] Fig.11 Another timing diagram 1100 depicting an example process for training APs and STAs for TX beamforming according to some implementations is shown. In some aspects, Fig.11 The training process of may represent at least a portion of a beamforming training operation that may be performed on a carrier frequency above 7 GHz (such as a directional link). In some implementations, the APs may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7In some implementations, the STAs may be respectively Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 An example of a non-AP MLD 720 is shown.

[0131] The AP performs TX beam refinement between time t0 and t1 by sending a PPDU including a certain number (N) of TRNs while the STA is in the best RX beam direction (RS) associated with the STA (such as Fig. 10B STA RX sector sweep or Fig. 10C More specifically, the AP sends N TRNs on N TX beam directions (T1-TN), respectively, and the STA attempts to receive each of the N TRNs via the RX sector associated with the RS beam direction. For example, each of the T1-TN beam directions can be associated with a corresponding TX sector of the AP. In some implementations, the PPDU can carry beam management information associated with the N TRNs (such as reference beam information). Fig. 10A The STA measures the signal power of each received TRN and selects the best TX beam direction associated with the signal power (such as the TX beam direction that produces the highest measured signal power). At time t2, the STA provides feedback to the AP indicating the best TX beam direction (such as the best sector ID or the best element ID).

[0132] The STA performs TX beam refinement between time t3 and t4 by sending a PPDU including a certain number (M) of TRNs, while the AP is refining the TX beam in the best RX beam direction (RA) associated with the AP (such as Fig. 10B AP RX sector sweep or Fig. 10C More specifically, the STA sends M TRNs on M TX beam directions (T1-TM), respectively, and the AP attempts to receive each of the M TRNs via the RX sector associated with the RS beam direction. For example, each of the T1-TM beam directions may be associated with a corresponding TX sector of the STA. In some implementations, the PPDU may carry beam management information associated with the M TRNs (such as reference beam information). Fig. 10AThe AP measures the signal power of each received TRN and selects the best TX beam direction associated with the signal power (such as the TX beam direction that produces the highest measured signal power). At time t5, the AP provides feedback to the STA indicating the best TX beam direction (such as the best sector ID or the best element ID).

[0133] After time t5, the AP may tune its TX antenna in the optimal TX beam direction determined as a result of its TX beam refinement (between time t0 and t1) to send a beam to the STA on the directional link. Similarly, the STA may tune its TX antenna in the optimal TX beam direction determined as a result of its TX beam refinement (between time t3 and t4) to send a beam to the AP on the directional link. In some implementations, the beam refinement protocol may be used in conjunction with data communications. In such implementations, the TRN may be appended to the end of the PPDU that includes the data portion. For example, referring to Fig.11 , a PPDU sent by an AP (between time t0 and t1) may include a data portion (between the PHY preamble and the TRN) carrying data intended for the STA. Similarly, a PPDU sent by a STA (between time t3 and t4) may include a data portion (between the PHY preamble and the TRN) carrying data intended for the AP.

[0134] Aspects of the present disclosure recognize that when TX beamforming is used at a transmitting device in conjunction with RX beamforming at a receiving device (such as when performing reference Fig.9A , Fig. 9B , Fig. 10B , Fig. 10C and Fig.11 The beamforming gain is greater than when the receiving device is operating in omni mode when TX beamforming is used at the transmitting device (such as when performing any of the training processes described in reference Fig. 10A In some aspects, when transmitting a beam to a receiving device configured for RX beamforming, a "Data PHY" (DPHY) PPDU format may be used, and when transmitting a beam to a receiving device operating in omni-directional mode, a "Control PHY" (CPHY) PPDU format may be used. More specifically, the CPHY PPDU format may be designed to overcome unilateral beamforming gain on directional links compared to the DPHY PPDU format. In some implementations, the CPHY PPDU format and the DPHY PPDU format may conform to existing PPDU formats associated with sub-7 GHz bands.

[0135] As described above, wireless communications at higher carrier frequencies may suffer from greater phase noise than wireless communications at lower frequency bands. For example, increasing the carrier frequency from 5.8 GHz to 60 GHz results in a 10-fold increase in phase noise. Aspects of the present disclosure recognize that phase noise can be mitigated by increasing the subcarrier spacing (SCS) between modulated subcarriers. As described in reference Figure 2A As described, the existing WLAN packet format includes that the L-STF is modulated on every 4 subcarriers across a given bandwidth to support carrier frequency offset (CFO) estimation up to 2 subcarriers apart. In addition, the local oscillator (LO) implemented by the existing WLAN transmitter and receiver is required to be accurate to ±20ppm. As such, the existing WLAN architecture can support CFO up to ±40ppm (between the transmitter and receiver), which is equivalent to ±2.4MHz in the 60GHz band and ±1.8MHz in the 45GHz band. In order to support CFO up to ±2.4MHz, the SCS associated with the L-STF should be greater than or equal to 1.2MHz.

[0136] In some aspects, a wireless communication device (such as an AP or STA) may up-clock a PPDU for transmission at a carrier frequency above 7 GHz, where the PPDU conforms to an existing PPDU format associated with a frequency band below 7 GHz. As used herein, the term "up-clocking" refers to increasing the frequency of a clock signal used to convert the PPDU between the frequency domain and the time domain (over a frequency (f0) associated with an existing PPDU format), and up-clocking the frequency (f s ) to f0 is referred to herein as the "upward clocking ratio" (where ). For example, the clock signal may be provided to a digital-to-analog converter (DAC) that samples the output of an inverse fast Fourier transform (IFFT). The IFFT transforms a certain number (n) of modulated subcarriers representing the PPDU into n time domain samples. In some aspects, the clock signal frequency f s With IFFT size (n IFFT ) may produce an SCS greater than or equal to 1.2 MHz, where the SCS represents the spacing between subcarriers on which the PHY preamble (including L-STF) of the PPDU is modulated. More specifically, the SCS as a result of upward clocking (SCS U ) may be a multiple of the SCS (SCS0) associated with the existing PPDU format, where SCS U =R×SCS0.

[0137] Fig.121 is a block diagram of an example TX processing chain 1200 for a wireless communication device according to some implementations. The TX processing chain 1200 is configured to process a PPDU 1201 for transmission as a radio frequency (RF) signal 1205 over a directional link. In some aspects, the PPDU 1201 may be Figure 3 In some implementations, the wireless communication devices may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7 In some other implementations, the wireless communication devices may be respectively Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 is an example of a non-AP MLD 720. Therefore, the directional links may be Figure 7 Directed link 704 or Figure 8 An example of any one of the directional links 804. For simplicity, Fig.12 Only a single spatial stream of the TX processing chain 1200 is depicted. In actual implementations, the TX processing chain 1200 may include any number of spatial streams.

[0138] The TX processing chain 1200 includes a cluster mapper 1210, an orthogonal frequency division multiplexing (OFDM) modulator 1220, an RF mixer 1230, and a power amplifier (PA) 1240. The cluster mapper 1210 maps the PPDU 1201 to one or more frequency domain (FD) symbols 1202 associated with a modulation scheme. Example suitable modulation schemes include binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), and quadrature amplitude modulation (QAM). The OFDM modulator 1220 modulates the FD symbols 1202 onto a set of orthogonal subcarriers and converts the modulated subcarriers into a time-varying TX signal 1203. The RF mixer 1230 up-converts the TX signal 1203 to a carrier frequency, and the power amplifier 1240 amplifies the resulting RF signal 1205 for transmission via one or more antennas 1250. For example, the RF mixer 1230 may modulate the TX signal 1203 onto a LO signal 1204 oscillating at the carrier frequency. exist Fig.12 In the example of , the carrier frequency associated with LO signal 1204 is shown to be above 7 GHz. In some specific implementations, the carrier frequency can be in the 60 GHz band. In some other specific implementations, the carrier frequency can be in the 45 GHz band.

[0139] As described above, many existing WLAN architectures are designed for wireless communications on carrier frequencies below 7 GHz (such as in the 2.4 GHz, 5 GHz, or 6 GHz bands). In some aspects, existing WLAN hardware can be reused to support wireless communications on carrier frequencies above 7 GHz. For example, the TX processing chain 1200 can receive an LO signal 1204 from a local oscillator accurate to ±20 ppm. As described above, increasing the carrier frequency of the LO signal 1204 also increases the phase noise associated with the RF signal 1205. For example, operating the local oscillator at 60 GHz can produce a CFO of ±2.4 MHz between the transmitter and the receiver. According to the existing version of the IEEE 802.11 standard, the PHY preamble of the PPDU 1201 includes an L-STF with a 1x symbol duration associated with an SCS equal to 312.5 KHz, which can support CFO estimates separated by up to 2 subcarriers. As used herein, the term "1x SCS" refers to the subcarrier spacing between the subcarriers to which the L-STF is mapped. Therefore, to support CFO up to ±2.4 MHz, the 1x SCS associated with the PPDU 1201 should be greater than or equal to 1.2 MHz.

[0140] Aspects of the present disclosure recognize that any SCS greater than or equal to 1.2 MHz may not be suitable for wireless communications on carrier frequencies below 7 GHz. As such, existing WLAN communication protocols for wireless communications below 7 GHz, such as IEEE 802.11be, 11ax, 11ac, and earlier revisions of the IEEE 802.11 standard, do not define a PPDU format or tone plan with an SCS greater than or equal to 1.2 MHz. In some aspects, the TX processing chain 1200 may receive a PPDU 1201 formatted for transmission on a carrier frequency below 7 GHz, and may up-clock the PPDU 1201 to a wider bandwidth suitable for transmission on a carrier frequency above 7 GHz, such as in a 60 GHz or 45 GHz band. For example, the wider bandwidth is achieved by extending the subcarriers to which the PPDU 1201 is mapped. In some implementations, the TX processing chain 1200 can up-clock the PPDU 1201 so that the 1x SCS associated with the PPDU 1201 is greater than or equal to 1.2 MHz.

[0141] In some implementations, the PPDU 1201 may conform to a PPDU format defined by the IEEE 802.11ac revision of the IEEE 802.11 standard (also referred to as a "11ac PPDU format"). For example, the PPDU 1201 may conform to a 11ac PPDU format associated with a 20 MHz, 40 MHz, 80 MHz, 80 MHz+80 MHz, or 160 MHz channel bandwidth (in a sub-7 GHz frequency band), and may be up-clocked for transmission over an 80 MHz, 160 MHz, 320 MHz, 480 MHz, 640 MHz, 960 MHz, 1.28 GHz, 1.92 GHz, or 2.56 GHz bandwidth wireless channel in a 60 GHz or 45 GHz frequency band. In some other implementations, the PPDU 1201 may conform to a PPDU format defined by the IEEE 802.11be (or 11ax) revision of the IEEE 802.11 standard (also referred to as a "11be PPDU format"). For example, PPDU 1201 may conform to an 11be PPDU format associated with a 20 MHz, 40 MHz, or 80 MHz channel bandwidth (in sub-7 GHz bands) and may be up-clocked for transmission on an 80 MHz, 160 MHz, 320 MHz, 480 MHz, 640 MHz, 960 MHz, 1.28 GHz, 1.92 GHz, or 2.56 GHz bandwidth wireless channel in a 60 GHz or 45 GHz band.

[0142] Fig.13A An example PPDU 1300 formatted according to the legacy PPDU format is shown. Fig.13A In the example of , the legacy PPDU format is a 11ac PPDU format associated with an 80MHz channel bandwidth. The PPDU 1300 includes a PHY preamble having a first portion 1301 and a second portion 1302, followed by a data portion 1303. The first preamble portion 1301 includes an L-STF, an L-LTF, an L-SIG, a first non-legacy signal field (SIG-A) spanning a first symbol (SIG-A1) and a second symbol (SIG-A2). The second preamble portion 1302 includes a non-legacy short training field (STF), one or more non-legacy long training fields (LTFs), and a second non-legacy signal field (SIG-B).

[0143] The IEEE 802.11ac revision of the IEEE 802.11 standard defines the non-legacy fields SIG-A1, SIG-A2, STF, LTF, and SIG-B as very high throughput (VHT) fields VHT-SIG-A1, VHT-SIG-A2, VHT-STF, VHT-LTF, and VHT-SIG-B, respectively. In some implementations, the PPDU 1300 may be up-clocked as a DPHY PPDU for wireless communication at carrier frequencies above 7 GHz. In such implementations, one or more of the signal fields in the first portion 1301 may be reused to carry beam management information 1305. Example beam management information 1305 may include PPDU type (indicating whether the PPDU 1300 is a regular PPDU or part of a sector sweep or beam refinement training process), training direction (such as TX or RX), beam tracking request (signaling the presence of a TRN at the end of the PPDU), training length (indicating the total number of BFT packets or TRNs to be sent), best antenna ID, best sector ID, the number of RX antennas of the transmitting device, or SNR report, etc. Fig.13A As shown, the first preamble part 1301 is replicated across four 20 MHz sub-bands spanning an 80 MHz bandwidth. According to the 11ac PPDU format, the first preamble part 1301, the second preamble part 1302, and the data part 1303 are mapped to the same subcarrier.

[0144] Fig. 13B According to some specific implementations, Fig.13A 13. The PPDU 1310 includes a PHY preamble 1311 followed by a packet extension (PE) or one or more TRNs 1314. In some aspects, the PPDU 1310 may represent an up-clocking of the PPDU 1300 by a factor M. In such aspects, the PHY preamble 1311 may be Fig.13A An example of the first preamble code portion 1301.

[0145] In some implementations, the PPDU 1310 may be a DPHY PPDU (such as Fig.9A , Fig. 9B and Fig. 10B Any BFT group in the BFT group, or Fig. 10C In such implementations, the beam management information may be carried in one or more of the signal fields L-SIG, SIG-A1, or SIG-A2. Fig.13A, the data portion 1303 and the PHY preamble fields associated with the data portion (such as the second preamble portion 1302) may be omitted from the PPDU 1310 to reduce overhead. In some aspects, the upward clocking may be performed by Fig.12 For example, OFDM modulator 1220 may up-clock PPDU 1300 by a factor of M to produce up-clocked PPDU 1310. Thus, PE or TRN 1314 is spread over an 80×M MHz bandwidth, and PHY preamble 1311 is replicated over four 20×M MHz subbands spanning the 80×M MHz bandwidth.

[0146] Fig. 13C According to some specific implementations, Fig.13A Another example of a PPDU format depicted in FIG. 1 is an up-clocked PPDU 1320. The PPDU 1320 includes a PHY preamble 1321, a data portion 1323, and a PE or one or more TRNs 1324. In some aspects, the PPDU 1320 may represent an up-clocking of the PPDU 1300 by a factor M. In such aspects, the PHY preamble 1321 and the data portion 1323 may be, respectively, Fig.13A An example of a first preamble portion 1301 and a data portion 1303.

[0147] In some implementations, PPDU 1320 may be a DPHY PPDU (such as Fig. 10C and Fig.11 In such implementations, the beam management information may be carried in one or more of the signal fields L-SIG, SIG-A1, or SIG-A2, and the data portion 1323 may carry data intended for a receiving device (such as an AP or STA). In some implementations, the PPDU 1320 may be omitted. Fig.13A In some other implementations, the PPDU 1320 may also include one or more non-legacy LTFs 1322, for example, to support multiple spatial streams (N SS >1) data transmission. In some aspects, the upward clock control can be performed by Fig.12The OFDM modulator 1220 may be implemented by the OFDM modulator 1220. For example, the OFDM modulator 1220 may up-clock the PPDU 1300 by a factor of M to produce an up-clocked PPDU 1320. Therefore, the LTF 1322 (if any), the data portion 1323, and the PE or TRN 1324 are spread over the 80×M MHz bandwidth, and the PHY preamble 1321 (excluding the LTF 1322) is replicated over four 20×M MHz subbands spanning the 80×M MHz bandwidth.

[0148] Fig.14A An example PPDU 1400 formatted according to the legacy PPDU format is shown. Fig.14A In the example of , the legacy PPDU format is an 11be PPDU format associated with a 20 MHz channel bandwidth. The PPDU 1400 includes a PHY preamble having a first portion 1401 and a second portion 1402, followed by a data portion 1403 and a PE 1404. The first preamble portion 1401 includes an L-STF, an L-LTF, an L-SIG, an RL-SIG, a first non-legacy signal field (SIG1), and a second non-legacy signal field (SIG2). The second preamble portion 1402 includes a non-legacy short training field (STF) and one or more non-legacy long training fields (LTF).

[0149] The IEEE 802.11be revision of the IEEE 802.11 standard defines the first non-legacy signal field SIG1 as a universal signal field (U-SIG), and defines the remaining non-legacy fields SIG2, STF, and LTF as extremely high throughput (EHT) fields EHT-SIG, EHT-STF, and EHT-LTF, respectively. In some implementations, the PPDU 1400 may be up-clocked as a DPHY PPDU for wireless communication at a carrier frequency greater than 7 GHz. In such implementations, one or more of the signal fields in the first portion 1401 may be reused to carry beam management information 1405. Example beam management information 1305 may include PPDU type, training direction, beam tracking request, training length, best antenna ID, best sector ID, number of RX antennas of the transmitting device, or SNR report, etc. According to the 11be PPDU format, the data portion 1403 (and PE1404) is mapped to each consecutive data subcarrier associated with a 256-subcarrier tone plan (the 256-subcarrier tone plan includes 234 data subcarriers and 8 pilot subcarriers). In contrast, the L-STF is mapped to every 4 data subcarriers associated with a 64-subcarrier tone plan, and the rest of the first preamble portion 1401 is mapped to each consecutive data subcarrier associated with the 64-subcarrier tone plan. In this way, the SCS associated with the L-STF is 4 times larger than the SCS associated with the data portion 1403.

[0150] Fig. 14B According to some specific implementations, Fig.14A 14. The PPDU 1410 includes a PHY preamble 1411 followed by a PE or one or more TRNs 1414. In some aspects, the PPDU 1410 may represent an up-clocking of the PPDU 1400 by a factor M. In such aspects, the PHY preamble 1411 and the PE or TRN 1414 may be, respectively, Fig.14A An example of the first preamble code part 1401 and PE 1404.

[0151] In some implementations, the PPDU 1410 may be a DPHY PPDU (such as Fig.9A , Fig. 9B and Fig. 10B Any BFT group in the BFT group, or Fig. 10C In such implementation, Fig.14AThe signal fields L-SIG, RL-SIG, SIG 1 and SIG2 may be compressed or aggregated into a single DPHY signal field (SIG) in the PHY preamble 1411 to carry beam management information. Fig.14A , the data portion 1403 and the PHY preamble fields associated with the data portion (such as the second preamble portion 1402) may be omitted from the PPDU 1410 to reduce overhead. In some aspects, the upward clocking may be performed by Fig.12 For example, OFDM modulator 1220 may up-clock PPDU 1400 by a factor M to generate up-clocked PPDU 1410. Fig.14A As described above, the SCS associated with the L-STF is four times larger than the SCS associated with the PE 1404. In other words, the symbol duration associated with the PHY preamble 1411 is equal to 1 / 4 of the symbol duration associated with the PE or TRN 1414. Therefore, the PHY preamble 1411 may span more than Fig. 13B The PHY preamble 1311 is significantly shorter in duration (given the same PPDU bandwidth).

[0152] Fig. 14C According to some specific implementations, Fig.14A Another example of a PPDU format depicted in FIG. 1 is an up-clocked PPDU 1420. The PPDU 1420 includes a PHY preamble 1421, a data portion 1423, and a PE or one or more TRNs 1424. In some aspects, the PPDU 1420 may represent an up-clocking of the PPDU 1400 by a factor M. In such aspects, the PHY preamble 1421, the data portion 1423, and the PE or TRN 1414 may be, respectively. Fig.14A An example of a first preamble portion 1401, a data portion 1403 and a PE 1404.

[0153] In some implementations, PPDU 1410 may be a DPHY PPDU (such as Fig. 10C and Fig.11 In such implementation, Fig.14A The signal fields L-SIG, RL-SIG, SIG1, and SIG2 may be compressed or aggregated into a single DPHY signal field (SIG) in the PHY preamble 1421 for carrying beam management information, and the data portion 1423 may carry data intended for a receiving device (such as an AP or STA). In some implementations, the PPDU 1420 may be omitted. Fig.14AIn some other implementations, the PPDU 1420 may also include one or more non-legacy LTFs 1422, for example, to support multiple spatial streams (N SS >1) data transmission. In some aspects, the upward clock control can be performed by Fig.12 For example, OFDM modulator 1220 may up-clock PPDU 1400 by a factor M to generate up-clocked PPDU 1420. Fig. 14B As described, the PHY preamble 1421 may span Fig. 13C The PHY preamble 1321 is significantly shorter in duration (given the same PPDU bandwidth).

[0154] Fig.15A An example PPDU 1500 formatted according to the legacy PPDU format is shown. Fig.15A In the example of , the legacy PPDU format is an 11be PPDU format associated with a 20MH channel bandwidth. More specifically, PPDU 1500 conforms to an extended range (ER) single user (SU) PPDU format. PPDU 1500 includes a PHY preamble having a first part 1501 and a second part 1502, followed by a data part 1503 and a PE 1504. The first preamble part 1501 includes an L-STF, an L-LTF, an L-SIG, a repetition of the L-SIG (RL-SIG), and four non-legacy signal fields (SIG1-SIG4). The second preamble part 1502 includes a non-legacy short training field (STF) and one or more non-legacy long training fields (LTF).

[0155] The IEEE 802.11be revision of the IEEE 802.11 standard defines each of the non-legacy signal fields SIG 1-SIG4 as U-SIG, and defines the remaining non-legacy fields STF and LTF as EHT fields EHT-STF and EHT-LTF, respectively. In addition, the STF sequence associated with the L-STF is repeated (by a factor of 2) in the time domain to produce an "extended L-STF". In some implementations, the PPDU 1500 may be clocked upward as a CPHY PPDU for wireless communication at a carrier frequency above 7 GHz. In such implementations, one or more of the signal fields in the first part 1501 may be reused to carry beam management information 1505. Example beam management information 1505 may include PPDU type, training direction, beam tracking request, training length, countdown (indicating the number of remaining training signals to be sent), sector ID, antenna ID, best antenna ID, best sector ID, the number of RX sectors or RX antennas of the transmitting device, or SNR report, etc. According to the 11be PPDU format, the data portion 1503 (and PE 1504) is mapped to each consecutive data subcarrier associated with the 256-subcarrier tone plan. In contrast, the L-STF is mapped to every 4 data subcarriers associated with the 64-subcarrier tone plan, while the rest of the first preamble portion 1501 is mapped to each consecutive data subcarrier associated with the 64-subcarrier tone plan. As such, the SCS associated with the L-STF is 4 times larger than the SCS associated with the data portion 1503.

[0156] Fig. 15B According to some specific implementations, Fig.15A 15. The PPDU 1510 includes a PHY preamble 1511 followed by a PE or one or more TRNs 1514. In some aspects, the PPDU 1510 may represent an up-clocking of the PPDU 1500 by a factor M. In such aspects, the PHY preamble 1511 and the PE or TRN 1514 may be, respectively, Fig.15A An example of the first preamble code part 1501 and PE 1504.

[0157] In some implementations, PPDU 1510 may be a CPHY PPDU that may be used for various beamforming training procedures (such as Fig. 10A Any BFT group in the BFT group and BRP-Rx with a single element measurement). In such a specific implementation, the beam management information can be carried in one or more of the signal fields L-SIG, RL-SIG, or SIG1-SIG4. For example, refer to Fig.15A, the data portion 1503 and the PHY preamble field associated with the data portion (such as the second preamble portion 1502) may be omitted from the PPDU 1510 to reduce overhead. Fig.15A As described above, the SCS associated with the L-STF is four times larger than the SCS associated with the PE 1504. Therefore, the first preamble portion 1501 may be up-clocked by a factor of M / 4 and replicated four times in the frequency domain to achieve the same SCS in the L-STF as in the PE 1504. In some aspects, the up-clocking may be performed by Fig.12 The OFDM modulator 1220 may be implemented by the OFDM modulator 1220. In some implementations, the OFDM modulator 1220 may up-clock the first preamble portion 1501 by a factor of 4 and may up-clock the remainder of the PPDU 1500 by a factor of M to produce the PPDU 1510. Thus, the PE or TRN 1514 is spread over a 20×M MHz bandwidth and the PHY preamble 1511 is replicated over four 5×M MHz subbands spanning the 20×M MHz bandwidth.

[0158] As reference FIG. 13A to FIG. 15B As described, the overhead associated with beamforming training can be reduced by reusing various fields of the PHY preamble to carry beam management information (and thus omitting the data portion of the PPDU). Aspects of the present disclosure recognize that the overhead associated with beamforming training can be reduced even further by offloading at least some of the signaling overhead associated with the beamforming training operations onto the anchor link.

[0159] Fig.16 A timing diagram 1600 is shown depicting an example beamforming training operation between an AP and a STA via an anchor link (AL) and a directional link (DL) according to some implementations. In some implementations, the AP may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7 In some implementations, the STAs may be respectively Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 An example of a non-AP MLD 720. For example, refer to Figure 7 and Figure 8 , the anchor link may be an example of either of the anchor links 702 or 802 , and the directional link may be an example of either of the directional links 704 or 804 .

[0160] At time t0, the AP (as a beamforming initiator) sends a trigger frame on the anchor link, which signals the start of a beamforming training operation to be performed on the directional link. In some implementations, the trigger frame may carry beam management setup information indicating one or more control parameters associated with the beamforming training operation. In the example of FIG. 10, the beamforming training operation is scheduled to occur from time t1 to t3. In some aspects, the trigger frame may provide a timing reference for wireless communication on the directional link. For example, the STA knows that the beamforming training operation will be performed on the directional link within a threshold duration of receiving the trigger frame on the anchor link. In this way, the STA can operate in a power saving mode on the directional link until the STA receives a trigger frame from the AP.

[0161] In some implementations, the beam management setup information may include a subset of the beam management information that would otherwise be included in the BFT packets sent during the beamforming training operation (such as Fig.13A Beam management information 1305, Fig.14A Beam management information 1405 or Fig.15A More specifically, the beam management setting information may include any information common to each of the BFT groups. Example beam management setting information may include, among other things, the total number of BFT groups to be sent by the AP (N), the number of TX antennas or sectors and RX antennas or sectors associated with the AP, or the total number of BFT groups allowed to be sent by the STA (K).

[0162] At time t1, the AP initiates a beamforming training operation by sending N BFT packets in various TX beam directions on a directional link (such as reference Fig.9A or Fig. 10A More specifically, at least one BFT group may be provided by each TX sector associated with an AP (such as Figure 6 In some implementations, each of the BFT packets may carry beam management information that may be used to train a TX sector or RX sector of the AP. More specifically, the beam management information may include any information that has not been signaled via a trigger frame. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of remaining BFT packets to send (L), sector ID or antenna ID, etc. Therefore, sending the trigger frame on the anchor link further reduces the overhead associated with each of the BFT packets.

[0163] The STA receives one or more of the BFT packets and compares the signal powers of the received BFT packets. At time t2, the STA provides feedback (FB) on the directional link indicating which of the BFT packets has the highest received signal power. For example, the feedback may include the best sector ID, the best antenna ID, or the SNR report, etc. In some implementations, the STA may further train the STA's RX antenna for RX beamforming based on the BFT packets sent by the AP between time t1 and t2 (such as reference Fig.9A In some other implementations, the STA may perform additional packet exchanges with the AP between times t2 and t3 to train the STA's RX antenna (such as reference Fig. 10B or Fig. 10C In some aspects, the AP may train its RX antennas for RX beamforming based on additional packet exchanges (such as described in reference Fig. 9B , Fig. 10B or Fig. 10C In some other aspects, the STA may train its TX antenna for TX beamforming based on additional packet exchanges (such as reference Fig. 9B or Fig. 10A described).

[0164] As reference Fig.16 As described, a trigger frame sent on the anchor link (at time t0) may provide a timing reference for communications on the directional link. In some implementations, the trigger frame may further provide a frequency reference for communications on the directional link. In such implementations, the same local oscillator of the AP may drive a carrier frequency used by the AP for wireless communications on each of the anchor link and the directional link, and the same local oscillator of the STA may drive a carrier frequency used by the STA for wireless communications on each of the anchor link and the directional link. Therefore, the STA may estimate the CFO on the anchor link based on the trigger frame received at time t0, and may use the CFO estimate associated with the anchor link to narrow the range of possible CFO estimates for the directional link (such as to within a few kilohertz). In this way, the anchor link and the directional link are "synchronized in frequency."

[0165] In some implementations, an AP may include a clock that controls the timing of wireless communications by the AP on a directional link and an anchor link, and a STA may include a clock that controls the timing of wireless communications by the STA on a directional link and an anchor link. For example, the same clock may control the time at which a trigger frame is sent on the anchor link and the time at which a BFT packet is sent on the directional link. In this way, the anchor link and the directional link are "synchronized in time." In some aspects, the anchor link and the directional link may be synchronized in both time and frequency. In such aspects, a receiving device may determine the timing and CFO associated with a BFT packet sent on the directional link based on the timing and CFO associated with a trigger frame sent on the anchor link. Therefore, these BFT packets may carry significantly less overhead than BFT packets that would otherwise be sent on the anchor link without a timing and frequency reference.

[0166] Fig.17A A timing diagram 1700 is shown depicting an example beamforming training operation between an AP and a STA via an anchor link (AL) and a directional link (DL) according to some implementations. In some implementations, the AP may be Figure 6 AP610 or Figure 8 Any of the APs 810 or Figure 7 In some implementations, the STAs may be respectively Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 An example of a non-AP MLD 720. For example, refer to Figure 7 and Figure 8 , the anchor link may be an example of either of the anchor links 702 or 802 , and the directional link may be an example of either of the directional links 704 or 804 .

[0167] exist Fig.17A In the example of , the directional link and the anchor link are synchronized in both time and frequency. In other words, the same local oscillator drives the carrier frequency used by the AP for wireless communication on each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the AP on each of the anchor link and the directional link. Similarly, the same local oscillator drives the carrier frequency used by the STA for wireless communication on each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the STA on each of the anchor link and the directional link.

[0168] At time t0, the AP (as the beamforming initiator) sends a trigger frame on the anchor link, which signals the start of the beamforming training operation to be performed on the directional link. Fig.17AIn the example of , the beamforming training operation is scheduled to occur from time t1 to t3. In some implementations, the trigger frame can carry beam management setup information indicating one or more parameters associated with the beamforming training operation. For example, the beam management setup information can include a subset of the beam management information that would otherwise be included in the BFT packets sent during the beamforming training operation (such as, respectively, Fig.13A Beam management information 1305, Fig.14A Beam management information 1405 or Fig.15A More specifically, the beam management setting information may include any information common to each of the BFT groups. Example beam management setting information may include, among other things, the total number of BFT groups to be sent by the AP (N), the number of TX antennas or sectors and RX antennas or sectors associated with the AP, or the total number of BFT groups allowed to be sent by the STA (K).

[0169] In some aspects, the trigger frame may further provide a timing and frequency reference for wireless communications on the directional link. For example, the beam management setup information may include timing and frequency information indicating the timing of wireless communications on the directional link and a CFO associated with the wireless communications. In other words, the STA knows that a beamforming training operation will be performed on the directional link at time t1 based on the timing information included in the trigger frame or derived from receiving the trigger frame. In addition, the STA may estimate the CFO associated with the wireless communications on the directional link based on the frequency information included in the trigger frame (such as the L-STF). Therefore, due to the beam management setup information carried in the trigger frame, the L-STF may be omitted from each BFT packet sent on the directional link. Fig.17A In the example of FIG. 4 , each BFT packet in the BFT packets is depicted as a short training sequence (TS).

[0170] At time t1, the AP initiates a beamforming training operation by sending N training sequences in various TX beam directions over the directional link (such as reference Fig.9A or Fig. 10A More specifically, at least one training sequence may be provided by each TX sector associated with the AP (such as Figure 6In some aspects, the STA may determine the sector ID (of the AP) from which the training sequence is sent based on the trigger frame received on the anchor link (at time t0) and the timing (such as indicated by the timestamp) of each training sequence. In some other aspects, each training sequence in the training sequence may carry beam management information that explicitly signals one or more training parameters. More specifically, the beam management information may include any information that has not been signaled via the trigger frame. In some specific implementations, each training sequence in the training sequence may be composed of a single LTF (such as a non-legacy LTF) designed to indicate one or more beam management parameters (such as a sector ID). In some other specific implementations, each training sequence in the training sequence may be composed of an LTF and a signal field (such as a non-legacy SIG) to carry additional beam management information (such as training direction, beam tracking request, sector ID, the number of remaining training sequences to be sent (L), or antenna ID).

[0171] The STA receives one or more of the training sequences and compares the signal powers of the received training sequences. At time t2, the STA provides feedback (FB) on the anchor link indicating which of the training sequences has the highest received signal power. For example, the feedback may include the best sector ID, the best antenna ID, or an SNR report, etc. In some implementations, the STA may further train the STA's RX antenna for RX beamforming based on the training sequence sent by the AP between time t1 and t2 (such as reference FB). Fig.9A In some other implementations, the STA may perform additional packet exchanges with the AP between times t2 and t3 to train the STA's RX antenna (such as reference Fig. 10B or Fig. 10C In some aspects, the AP may train its RX antennas for RX beamforming based on additional packet exchanges (such as described in reference Fig. 9B , Fig. 10B or Fig. 10C In some other aspects, the STA may train its TX antenna for TX beamforming based on additional packet exchanges (such as reference Fig. 9B or Fig. 10A described).

[0172] Fig. 17B Another timing diagram 1710 depicting example beamforming training operations between an AP and a STA over an anchor link (AL) and a directional link (DL) according to some implementations is shown. In some implementations, the AP may be Figure 6 AP 610 or Figure 8 Any of the APs 810 or Figure 7In some implementations, the STAs may be respectively Figure 6 STA 620 or Figure 8 Any of the STA 820 or Figure 7 An example of a non-AP MLD 720. For example, refer to Figure 7 and Figure 8 , the anchor link may be an example of either of the anchor links 702 or 802 , and the directional link may be an example of either of the directional links 704 or 804 .

[0173] exist Fig. 17B In the example of , the directional link and the anchor link are synchronized in both time and frequency. In other words, the same local oscillator drives the carrier frequency used by the AP for wireless communication on each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the AP on each of the anchor link and the directional link. Similarly, the same local oscillator drives the carrier frequency used by the STA for wireless communication on each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the STA on each of the anchor link and the directional link.

[0174] At time t0, the AP (as the beamforming initiator) sends a trigger frame on the anchor link, which signals the start of the beamforming training operation to be performed on the directional link. Fig. 17B In the example of , the beamforming training operation is scheduled to occur from time t1 to t3. In some implementations, the trigger frame can carry beam management setup information indicating one or more parameters associated with the beamforming training operation. For example, the beam management setup information can include a subset of the beam management information that would otherwise be included in the BFT packets sent during the beamforming training operation (such as, respectively, Fig.13A Beam management information 1305, Fig.14A Beam management information 1405 or Fig.15A More specifically, the beam management setting information may include any information common to each of the BFT groups. Example beam management setting information may include, among other things, the total number of BFT groups to be sent by the AP (N), the number of TX antennas or sectors and RX antennas or sectors associated with the AP, or the total number of BFT groups allowed to be sent by the STA (K).

[0175] In some aspects, the trigger frame may further provide a timing and frequency reference for wireless communications on the directional link. For example, the beam management setup information may include timing and frequency information indicating the timing of wireless communications on the directional link and a CFO associated with the wireless communications. In other words, the STA knows that a beamforming training operation will be performed on the directional link at time t1 based on the timing information included in the trigger frame or derived from receiving the trigger frame. In addition, the STA may estimate the CFO associated with the wireless communications on the directional link based on the frequency information included in the trigger frame (such as the L-STF). Therefore, due to the beam management setup information carried in the trigger frame, the L-STF may not be present in each BFT packet sent on the directional link. Fig.17A In the example of FIG. 4 , each BFT packet in the BFT packets is depicted as a short training sequence (TS).

[0176] At time t1, the AP initiates a beamforming training operation by sending N training sequences in various TX beam directions over the directional link (such as reference Fig.9A and Fig. 10A More specifically, at least one training sequence may be provided by each TX sector associated with the AP (such as Figure 6 In some aspects, the STA may determine the sector ID (of the AP) from which the training sequence is sent based on the trigger frame received on the anchor link (at time t0) and the timing (such as indicated by the timestamp) of each training sequence. In some other aspects, each training sequence in the training sequence may carry beam management information that explicitly signals one or more training parameters. More specifically, the beam management information may include any information that has not been signaled via the trigger frame. In some specific implementations, each training sequence in the training sequence may be composed of a single LTF (such as a non-legacy LTF) designed to indicate one or more beam management parameters (such as a sector ID). In some other specific implementations, each training sequence in the training sequence may be composed of an LTF and a signal field (such as a non-legacy SIG) to carry additional beam management information (such as training direction, beam tracking request, sector ID, the number of remaining training sequences to be sent (L), or antenna ID).

[0177] The STA receives one or more training sequences in the training sequence and compares the signal powers of the received training sequences. At time t2, the STA provides feedback (FB) on the directional link indicating which training sequence in the training sequence has the highest received signal power. In some implementations, the feedback may consist of a single LTF (such as a non-legacy LTF) designed to indicate the best sector ID. In some other implementations, the feedback may consist of an LTF and a signal field (such as a non-legacy SIG) to carry additional information, such as the best antenna ID or SNR report. In some implementations, the STA may further train the STA's RX antenna for RX beamforming based on the training sequence sent by the AP between time t1 and t2 (such as a reference signal). Fig.9A In some other implementations, the STA may perform additional packet exchanges with the AP between times t2 and t3 to train the STA's RX antenna (such as reference Fig. 10B or Fig. 10C In some aspects, the AP may train its RX antennas for RX beamforming based on additional packet exchanges (such as described in reference Fig. 9B , Fig. 10B or Fig. 10C In some other aspects, the STA may train its TX antenna for TX beamforming based on additional packet exchanges (such as reference Fig. 9B or Fig. 10A described).

[0178] Fig.18 1800 for wireless communication supporting 60 GHz beam management for WLAN. In some implementations, process 1800 can be performed by an AP (such as those described above, respectively, with reference to Figure 1 and Figure 5A The process 1800 may be performed by a wireless communication device operating as a STA (such as any of the APs 102 or 502 described above) or operating within an AP. In some other specific implementations, the process 1800 may be performed by a wireless communication device operating as a STA (such as the APs 102 or 502 described above). Figure 1 and Figure 5B The method is performed by a wireless communication device operating (either of the STA 104 or 504 described) or operating within a STA.

[0179] In some implementations, process 1800 begins in block 1802 by sending a number (N) of BFT packets in N TX beam directions, respectively, on a first wireless communication link, wherein each of the N BFT packets includes a PHY preamble carrying corresponding beam management information indicating the TX beam direction in which the BFT packet is sent. In block 1804, process 1800 continues by receiving a first feedback associated with a first TX beam direction of the N TX beam directions from a responding device. In block 1806, process 1800 continues by sending a PPDU in the first TX beam direction on the first wireless communication link.

[0180] In some aspects, process 1800 may further include associating with the responding device via a second wireless communication link, wherein the N BFT packets are sent over the first wireless communication link based on associating with the responding device via the second wireless communication. In some implementations, the first wireless communication link may operate at a carrier frequency above 7 GHz, and the second wireless communication link may operate at a carrier frequency below 7 GHz.

[0181] In some implementations, each of the N BFT packets may consist of only a PHY preamble. In some implementations, the beam management information may include at least one of the following: a PPDU type, a training direction, a beam tracking request, a number of BFT packets N, a number of BFT packets remaining to be sent, a TX sector ID or TX antenna ID associated with the TX beam direction in which the BFT packet is sent, or a number of RX sectors or RX antennas associated with the wireless communication device. In some aspects, the first feedback may be carried in the PHY preamble of the PPDU. In some implementations, the first feedback may include a TX sector ID or TX antenna ID indicated by a BFT packet sent in a first TX beam direction, an SNR report, or a number of RX sectors or RX antennas associated with the responding device.

[0182] In some aspects, process 1800 may further include: retransmitting N BFT packets in N TX beam directions respectively on the first wireless communication link based on the number (M) of RX sectors associated with the responding device. In such aspects, each of the N BFT packets may be sent M times in the corresponding TX beam direction. In some aspects, process 1800 may further include: receiving a certain number (K) of BFT packets on the first wireless communication link, each of the certain number (K) of BFT packets carrying beam management information indicating a corresponding beam direction associated with the received BFT packet; measuring the signal power of each of the K received BFT packets; and sending a second feedback associated with the received BFT packet having the highest signal power among the measured signal powers to the responding device. In such aspects, the first feedback may be carried in the K received BFT packets.

[0183] In some aspects, process 1800 may further include: receiving one or more training signals on the first wireless communication link, wherein each of the one or more training signals is received via multiple antennas tuned in a corresponding RX beam direction; measuring the power of each of the L received training signals; and receiving a PPDU from a responding device via multiple antennas tuned in the RX beam direction that receives the training signal with the highest signal power among the measured signal powers. In some specific implementations, each of the multiple training signals may represent a corresponding PPDU. In some other specific implementations, each of the multiple training signals may represent a corresponding TRN of the same PPDU.

[0184] Fig.19 1900 for wireless communication supporting 60 GHz beam management for WLAN. In some implementations, process 1900 can be performed by an AP (such as those described above, respectively, with reference to Figure 1 and Figure 5A The process 1900 may be performed by a wireless communication device operating as a STA (such as any of the APs 102 or 502 described above) or operating within an AP. In some other specific implementations, the process 1900 may be performed by a wireless communication device operating as a STA (such as the APs 102 or 502 described above). Figure 1 and Figure 5B The method is performed by a wireless communication device operating (either of the STA 104 or 504 described) or operating within a STA.

[0185] In some implementations, process 1900 begins in block 1902 by receiving a number (N) of BFT packets on a first wireless communication link, wherein each of the N BFT packets includes a PHY preamble carrying beam management information indicating a corresponding beam direction associated with the received BFT packet. In block 1904, process 1900 continues by measuring a signal power of each of the received BFT packets. In block 1906, process 1900 continues by sending a first feedback associated with the received BFT packet having a highest signal power among the measured signal powers to an initiating device. In block 1908, process 1900 continues by receiving a PPDU on the first wireless communication link based on the first feedback.

[0186] In some aspects, process 1900 may further include associating with the initiating device via a second wireless communication link, wherein the N BFT packets are received on the first wireless communication link based on associating with the initiating device via the second wireless communication link. In some implementations, the first wireless communication link may operate at a carrier frequency above 7 GHz, and the second wireless communication link may operate at a carrier frequency below 7 GHz.

[0187] In some implementations, each of the N BFT packets may consist of only a PHY preamble. In some implementations, the beam management information may include at least one of the following: a PPDU type, a training direction, a beam tracking request, a number of BFT packets sent by the initiating device, a number of BFT packets remaining to be sent, a TX sector ID or TX antenna ID associated with the beam direction, or a number of RX sectors or RX antennas associated with the initiating device. In some aspects, the first feedback may be carried in the PHY preamble of the PPDU. In some implementations, the first feedback may include a TX sector ID or TX antenna ID indicated by the received BFT packet with the highest signal power, an SNR report, or a number of RX sectors or RX antennas associated with the wireless communication device.

[0188] In some aspects, the N BFT packets may be received via multiple antennas tuned in a certain number (M) of RX beam directions. In some specific implementations, at least one BFT packet of the N BFT packets is received multiple times based on tuning the multiple antennas in multiple RX beam directions in the M RX beam directions respectively. In some aspects, the process 1900 may also include: sending a certain number (K) of BFT packets in K TX beam directions respectively on the first wireless communication link; receiving second feedback associated with a first TX beam direction in the K TX beam directions from the initiator device; and sending a PPDU in the first TX beam direction on the first wireless communication link. In some specific implementations, the first feedback may be carried in the K sent BFT packets.

[0189] In some aspects, process 1900 may further include: receiving one or more training signals on the first wireless communication link, wherein each of the one or more training signals is received via multiple antennas tuned in a corresponding RX beam direction; measuring the signal power of each of the one or more received training signals; and receiving a PPDU from the initiating device via the multiple antennas tuned in the RX beam direction that receives the training signal having the highest signal power among the measured signal powers. In some implementations, each of the multiple training signals may represent a corresponding PPDU. In some other implementations, each of the multiple training signals may represent a corresponding TRN of the same PPDU.

[0190] Fig. 20 2000 according to some specific implementations. In some specific implementations, the wireless communication device 2000 is configured to perform the above reference Fig.18 The wireless communication device 2000 may be the process 1800 described above. Figure 4 Example implementations of the described wireless communication device 400. For example, the wireless communication device 2000 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0191] The wireless communication device 2000 includes a receiving component 2010, a communication manager 2020, and a transmitting component 2030. The communication manager 2020 also includes a beam training initiation component 2022. Portions of the beam training initiation component 2022 may be implemented at least in part in hardware or firmware. In some aspects, the beam training initiation component 2022 is implemented at least in part as software stored in a memory, such as the memory 408. For example, portions of the beam training initiation component 2022 may be implemented as non-transitory instructions (or "code") that may be executed by a processor, such as the processor 406, to perform the functions or operations of the corresponding component.

[0192] The receiving component 2010 is configured to receive an RX signal from one or more other wireless communication devices through a wireless channel. The sending component 2030 is configured to send a TX signal to one or more other wireless communication devices through a wireless channel. The communication manager 2020 is configured to control or manage communication with one or more other wireless communication devices. In some specific implementations, the beam training initiating component 2022 may send a certain number (N) of BFT packets in N TX beam directions respectively on the first wireless communication link, wherein each of the N BFT packets includes a PHY preamble code, and the PHY preamble code carries corresponding beam management information indicating the TX beam direction in which the BFT packet is sent. In some specific implementations, the receiving component 2010 may receive feedback associated with a first TX beam direction in the N TX beam directions from a responding device. In some specific implementations, the sending component 2030 may send a PPDU in the first TX beam direction on the first wireless communication link.

[0193] Fig.21 2 shows a block diagram of an example wireless communication device 2100 according to some implementations. In some implementations, the wireless communication device 2100 is configured to perform the above-referenced Fig.19 The wireless communication device 2100 may be the process 1900 described above. Figure 4 Example implementations of the described wireless communication device 400. For example, the wireless communication device 2100 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0194] The wireless communication device 2100 includes a receiving component 2110, a communication manager 2120, and a transmitting component 2130. The communication manager 2120 also includes a beam training response component 2122. Portions of the beam training response component 2122 may be implemented at least in part in hardware or firmware. In some aspects, the beam training response component 2122 is implemented at least in part as software stored in a memory, such as the memory 408. For example, portions of the beam training response component 2122 may be implemented as non-transitory instructions (or "code") that may be executed by a processor, such as the processor 406, to perform the functions or operations of the corresponding component.

[0195] The receiving component 2110 is configured to receive an RX signal from one or more other wireless communication devices through a wireless channel. The sending component 2130 is configured to send a TX signal to one or more other wireless communication devices through a wireless channel. The communication manager 2120 is configured to control or manage communication with one or more other wireless communication devices. In some specific implementations, the beam training response component 2122 may receive a certain number (N) of BFT packets on a first wireless communication link, and may measure the signal power of each of the received BFT packets, wherein each of the N BFT packets includes a PHY preamble that carries beam management information indicating a corresponding beam direction associated with the received BFT packet. In some specific implementations, the sending component 2130 may send feedback associated with the received BFT packet having the highest signal power among the measured signal powers to the initiating device. In some specific implementations, the receiving component 2110 may receive a PPDU on the first wireless communication link based on the first feedback.

[0196] Specific implementation examples are described in the following numbered clauses:

[0197] 1. A method for wireless communication by a wireless communication device, the method comprising:

[0198] Sending a certain number (N) of beamforming training (BFT) packets in N transmit (TX) beam directions respectively on a first wireless communication link, each of the N BFT packets comprising a PHY preamble code, the PHY preamble code carrying corresponding beam management information indicating the TX beam direction in which the BFT packet is sent;

[0199] receiving, from a responding device, first feedback associated with a first TX beam direction of the N TX beam directions; and

[0200] A physical layer convergence protocol (PLCP) protocol data unit (PPDU) is transmitted in the first TX beam direction over the first wireless communication link.

[0201] 2. The method according to clause 1, further comprising:

[0202] The N BFT packets are sent over the first wireless communication link based on being associated with the responding device via the second wireless communication link.

[0203] 3. A method according to any of clauses 1 or 2, wherein the first wireless communication link operates at a carrier frequency above 7 GHz and the second wireless communication link operates at a carrier frequency below 7 GHz.

[0204] 4. A method according to any of clauses 1 to 3, wherein each of the N BFT packets consists only of the PHY preamble.

[0205] 5. A method according to any one of clauses 1 to 4, wherein the beam management information includes at least one of the following: PPDU type, training direction, beam tracking request, the number N of BFT packets, the number of BFT packets remaining to be sent, a TX sector identifier (ID) or TX antenna ID associated with the TX beam direction for sending the BFT packet, or the number of receive (RX) sectors or RX antennas associated with the wireless communication device.

[0206] 6. A method as described in any of clauses 1 to 5, wherein the first feedback is carried in a PHY preamble of a PPDU.

[0207] 7. A method according to any one of clauses 1 to 6, wherein the first feedback includes the TX sector ID or the TX antenna ID indicated by the BFT packet sent in the first TX beam direction, a signal-to-noise ratio (SNR) report, or the number of RX sectors or RX antennas associated with the responding device.

[0208] 8. The method according to any one of clauses 1 to 7, further comprising:

[0209] The N BFT packets are retransmitted in the N TX beam directions respectively on the first wireless communication link based on the number (M) of RX sectors associated with the responding device.

[0210] 9. A method according to any of clauses 1 to 8, wherein each of the N BFT packets is sent M times in a corresponding TX beam direction.

[0211] 10. The method according to any one of clauses 1 to 9, further comprising:

[0212] receiving a certain number (K) of BFT packets on the first wireless communication link, the certain number (K) of BFT packets each carrying beam management information indicating a corresponding beam direction associated with the received BFT packet;

[0213] measuring a signal power of each of the K received BFT packets; and

[0214] Second feedback associated with the received BFT packet having a highest signal power among the measured signal powers is sent to the responding device.

[0215] 11. A method as described in any of clauses 1 to 10, wherein the first feedback is carried in K received BFT packets.

[0216] 12. The method according to any one of clauses 1 to 11, further comprising:

[0217] receiving one or more training signals over the first wireless communication link, each of the one or more training signals being received via a plurality of antennas tuned in a corresponding RX beam direction;

[0218] measuring a signal power of each of the L received training signals; and

[0219] A PPDU is received from the responding device via the plurality of antennas tuned in the RX beam direction receiving the training signal having a highest signal power among the measured signal powers.

[0220] 13. A method according to any of clauses 1 to 12, wherein each training signal of the plurality of training signals represents a respective PPDU.

[0221] 14. A method according to any of clauses 1 to 12, wherein each training signal of the plurality of training signals represents a respective training (TRN) field of the same PPDU.

[0222] 15. A wireless communication device, comprising:

[0223] at least one memory; and

[0224] At least one processor, the at least one processor being communicatively coupled to the at least one memory, the at least one processor being configured to cause the wireless communication device to perform the method according to any one or more of clauses 1 to 14.

[0225] 16. A method for wireless communication by a wireless communication device, the method comprising:

[0226] receiving a number (N) of beamforming training (BFT) packets on a first wireless communication link, each of the N BFT packets including a physical layer (PHY) preamble carrying beam management information indicating a corresponding beam direction associated with the received BFT packet;

[0227] measuring a signal power of each of the received BFT packets;

[0228] sending, to the initiating device, first feedback associated with the received BFT packet having a highest signal power among the measured signal powers; and

[0229] A physical layer convergence protocol (PLCP) protocol data unit (PPDU) is received over the first wireless communication link based on the first feedback.

[0230] 17. The method according to clause 16, further comprising:

[0231] The initiator device is associated with the initiator device via a second wireless communication link, and the N BFT packets are received on the first wireless communication link based on being associated with the initiator device via the second wireless communication link.

[0232] 18. A method according to any of clauses 16 or 17, wherein the first wireless communication link operates at a carrier frequency above 7 GHz and the second wireless communication link operates at a carrier frequency below 7 GHz.

[0233] 19. A method as described in any of clauses 16 to 18, wherein each of the N BFT packets consists only of the PHY preamble.

[0234] 20. A method according to any one of clauses 16 to 19, wherein the beam management information includes at least one of the following: PPDU type, training direction, beam tracking request, the number of BFT packets sent by the initiating device, the number of BFT packets remaining to be sent, a transmit (TX) sector identifier (ID) or a TX antenna ID associated with the beam direction, or the number of receive (RX) sectors or RX antennas associated with the initiating device.

[0235] 21. A method as described in any of clauses 16 to 20, wherein the first feedback is carried in a PHY preamble of a PPDU.

[0236] 22. A method according to any one of clauses 16 to 21, wherein the first feedback includes the TX sector ID or the TX antenna ID indicated by the received BFT packet with the highest signal power, a signal-to-noise ratio (SNR) report, or the number of RX sectors or RX antennas associated with the wireless communication device.

[0237] 23. A method as described in any of clauses 16 to 22, wherein the N BFT packets are received via multiple antennas tuned in a number (M) of RX beam directions.

[0238] 24. A method according to any of clauses 16 to 23, wherein at least one of the N BFT packets is received multiple times based on tuning the multiple antennas in multiple RX beam directions of the M RX beam directions respectively.

[0239] 25. The method according to any one of clauses 16 to 24, further comprising:

[0240] Sending a certain number (K) of BFT packets in K TX beam directions respectively on the first wireless communication link;

[0241] receiving, from the initiating device, second feedback associated with a first TX beam direction of the K TX beam directions; and

[0242] A PPDU is transmitted in the first TX beam direction over the first wireless communication link.

[0243] 26. A method as described in any of clauses 16 to 25, wherein the first feedback is carried in K transmitted BFT packets.

[0244] 27. The method according to any one of clauses 16 to 26, further comprising:

[0245] receiving one or more training signals over the first wireless communication link, each of the one or more training signals being received via a plurality of antennas tuned in a corresponding RX beam direction;

[0246] measuring a signal power of each of the one or more received training signals; and

[0247] A PPDU is received from the initiating device via the plurality of antennas tuned in the RX beam direction receiving the training signal having a highest signal power among the measured signal powers.

[0248] 28. A method as described in any of clauses 16 to 27, wherein each training signal of the plurality of training signals represents a respective PPDU.

[0249] 29. A method as described in any of clauses 16 to 27, wherein each training signal of the plurality of training signals represents a respective training (TRN) field of the same PPDU.

[0250] 30. A wireless communication device, comprising:

[0251] at least one memory; and

[0252] At least one processor, the at least one processor being communicatively coupled to the at least one memory, the at least one processor being configured to cause the wireless communication device to perform the method according to any one or more of clauses 16 to 29.

[0253] As used herein, phrases referring to "at least one of" or "one or more of" a list of items refer to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover the following possibilities: only a, only b, only c, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a, b, and c. As used herein, "based on" is intended to be interpreted in an inclusive sense, unless otherwise expressly indicated. For example, "based on" may be used interchangeably with "based at least in part on," unless otherwise expressly indicated. Specifically, unless a phrase in the context refers to "based only on 'one'" or the equivalent, whether it is "based on 'one'" or "based at least in part on 'one'" may be based on "one" alone or on a combination of "one" and one or more other factors, conditions, or information.

[0254] The various illustrative components, logic, logic blocks, modules, circuits, operations, and algorithmic processes described in conjunction with the specific implementations disclosed herein may be implemented as electronic hardware, firmware, software, or a combination of hardware, firmware, or software, including the structures disclosed in this specification and their structural equivalents. This interchangeability of hardware, firmware, and software has been generally described in terms of their functionality and exemplified in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware, firmware, or software depends on the specific application and the design constraints imposed on the overall system.

[0255] Various modifications to the specific implementations described in this disclosure will be apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other specific implementations without departing from the spirit or scope of the disclosure. Therefore, the claims are not intended to be limited to the specific implementations shown herein, but are to be consistent with the broadest scope consistent with the disclosure, the principles and novel features disclosed herein.

[0256] Additionally, various features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations individually or in any suitable subcombination. Thus, although features may be described above as functioning in a particular combination, and even initially claimed as such, one or more features from a claimed combination may in some cases be deleted from the combination, and a claimed combination may be directed to a subcombination or a variation of a subcombination.

[0257] Similarly, although operations are depicted in a specific order in the figure, this should not be understood as requiring such operations to be performed in the specific order shown or in a sequential order, or performing all illustrated operations to achieve the desired result. In addition, the accompanying drawings may schematically depict one or more example processes in the form of a flow chart or a flow diagram. However, other operations not depicted can be incorporated into the example processes schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously or between any operations in the illustrated operations. In some environments, multitasking and parallel processing may be advantageous. In addition, the separation of various system components in the specific implementation described above should not be understood as requiring such separation in all specific implementations, but it should be understood as described program components and systems can usually be integrated together in a single software product, or be packaged in multiple software products.

Claims

1. A method for wireless communication performed by a wireless communication device, the method comprising: Sending a certain number (N) of beamforming training (BFT) packets in N transmit (TX) beam directions respectively on a first wireless communication link, wherein each of the N BFT packets includes a physical layer (PHY) preamble code, and the physical layer (PHY) preamble code carries corresponding beam management information indicating the TX beam direction in which the BFT packet is sent; receiving, from a responding device, first feedback associated with a first TX beam direction of the N TX beam directions; as well as A physical layer convergence protocol (PLCP) protocol data unit (PPDU) is transmitted in the first TX beam direction over the first wireless communication link.

2. The method according to claim 1, further comprising: The N BFT packets are sent over the first wireless communication link based on being associated with the responding device via the second wireless communication link.

3. The method of claim 2, wherein the first wireless communication link operates at a carrier frequency above 7 GHz and the second wireless communication link operates at a carrier frequency below 7 GHz.

4. The method of claim 1, wherein each of the N BFT packets consists only of the PHY preamble.

5. The method of claim 1 , wherein the beam management information comprises at least one of: a PPDU type, a training direction, a beam tracking request, the number N of BFT packets, the number of the BFT packets remaining to be sent, a TX sector identifier (ID) or a TX antenna ID associated with the TX beam direction in which the BFT packet is sent, or a number of receive (RX) sectors or RX antennas associated with the wireless communication device. The method of claim 5 , wherein the first feedback is carried in a PHY preamble of a PPDU.

7. The method of claim 6, wherein the first feedback comprises the TX sector ID or the TX antenna ID indicated by the BFT packet sent in the first TX beam direction, a signal-to-noise ratio (SNR) report, or the number of RX sectors or RX antennas associated with the responding device.

8. The method according to claim 1, further comprising: The N BFT packets are retransmitted in the N TX beam directions respectively on the first wireless communication link based on the number (M) of RX sectors associated with the responding device.

9. The method of claim 8, wherein each of the N BFT packets is transmitted M times in a corresponding TX beam direction.

10. The method according to claim 1, further comprising: receiving a certain number (K) of BFT packets on the first wireless communication link, the certain number (K) of BFT packets each carrying beam management information indicating a corresponding beam direction associated with the received BFT packet; Measuring a signal power of each of the K received BFT packets; as well as Second feedback associated with the received BFT packet having a highest signal power among the measured signal powers is sent to the responding device. The method of claim 10 , wherein the first feedback is carried in K received BFT packets.

12. The method according to claim 1, further comprising: receiving one or more training signals over the first wireless communication link, each of the one or more training signals being received via a plurality of antennas tuned in a corresponding RX beam direction; measuring a signal power of each of the one or more received training signals; as well as A PPDU is received from the responding device via the plurality of antennas tuned in the RX beam direction receiving the training signal having a highest signal power among the measured signal powers.

13. The method of claim 12, wherein each training signal of the plurality of training signals represents a corresponding PPDU.

14. The method of claim 12, wherein each of the plurality of training signals represents a corresponding training (TRN) field of the same PPDU.

15. A wireless communication device for wireless communication, the wireless communication device comprising: at least one memory; and at least one processor, the at least one processor being communicatively coupled to the at least one memory, the at least one processor being configured to cause the wireless communication device to: Sending a certain number (N) of beamforming training (BFT) packets in N transmit (TX) beam directions, respectively, each of the N BFT packets comprising a physical layer (PHY) preamble, the physical layer (PHY) preamble carrying corresponding beam management information indicating the TX beam direction in which the BFT packet is sent; receiving, from a responding device, first feedback associated with a first TX beam direction of the N TX beam directions; as well as A physical layer convergence protocol (PLCP) protocol data unit (PPDU) is transmitted in the first TX beam direction.

16. A method for wireless communication performed by a wireless communication device, the method comprising: receiving a number (N) of beamforming training (BFT) packets on a first wireless communication link, each of the N BFT packets including a physical layer (PHY) preamble carrying beam management information indicating a corresponding beam direction associated with the received BFT packet; measuring a signal power of each of the received BFT packets; sending, to the initiating device, first feedback associated with the received BFT packet having a highest signal power among the measured signal powers; as well as A physical layer convergence protocol (PLCP) protocol data unit (PPDU) is received over the first wireless communication link based on the first feedback.

17. The method according to claim 16, further comprising: The initiator device is associated with the initiator device via a second wireless communication link, and the N BFT packets are received on the first wireless communication link based on being associated with the initiator device via the second wireless communication link.

18. The method of claim 17, wherein the first wireless communication link operates at a carrier frequency above 7 GHz and the second wireless communication link operates at a carrier frequency below 7 GHz.

19. The method of claim 16, wherein each of the N BFT packets consists only of the PHY preamble.

20. The method of claim 16, wherein the beam management information comprises at least one of: a PPDU type, a training direction, a beam tracking request, a number of BFT packets sent by the initiating device, a number of the BFT packets remaining to be sent, a transmit (TX) sector identifier (ID) or a TX antenna ID associated with the beam direction, or a number of receive (RX) sectors or RX antennas associated with the initiating device.

21. The method of claim 20, wherein the first feedback is carried in a PHY preamble of a PPDU.

22. The method of claim 21 , wherein the first feedback comprises the TX sector ID or the TX antenna ID indicated by the received BFT packet having the highest signal power, a signal-to-noise ratio (SNR) report, or the number of RX sectors or RX antennas associated with the wireless communication device.

23. The method of claim 16, wherein the N BFT packets are received via multiple antennas tuned in a number (M) of RX beam directions. 24 . The method of claim 23 , wherein at least one of the N BFT packets is received multiple times based on tuning the multiple antennas in multiple RX beam directions among the M RX beam directions, respectively.

25. The method according to claim 16, further comprising: Sending a certain number (K) of BFT packets in K TX beam directions respectively on the first wireless communication link; receiving, from the initiating device, second feedback associated with a first TX beam direction of the K TX beam directions; as well as A PPDU is transmitted in the first TX beam direction over the first wireless communication link.

26. The method of claim 25, wherein the first feedback is carried in K transmitted BFT packets.

27. The method according to claim 16, further comprising: receiving one or more training signals over the first wireless communication link, each of the one or more training signals being received via a plurality of antennas tuned in a corresponding RX beam direction; measuring a signal power of each of the one or more received training signals; as well as A PPDU is received from the initiating device via the plurality of antennas tuned in the RX beam direction receiving the training signal having a highest signal power among the measured signal powers.

28. The method of claim 27, wherein each training signal of the plurality of training signals represents a corresponding PPDU.

29. The method of claim 27, wherein each of the plurality of training signals represents a corresponding training (TRN) field of the same PPDU.

30. A wireless communication device for wireless communication, the wireless communication device comprising: at least one memory; and at least one processor, the at least one processor being communicatively coupled to the at least one memory, the at least one processor being configured to cause the wireless communication device to: receiving a number (N) of beamforming training (BFT) packets, each of the number (N) of beamforming training (BFT) packets including a physical layer (PHY) preamble carrying beam management information indicating a respective beam direction associated with the received BFT packet; measuring a signal power of each of the received BFT packets; sending, to the initiating device, first feedback associated with the received BFT packet having a highest signal power among the measured signal powers; as well as A physical layer convergence protocol (PLCP) protocol data unit (PPDU) is received based on the first feedback.

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