60GHz Beam Management for Wireless Local Area Networks (WLANs)

Abstract

The present disclosure provides a method, device, and system for increasing carrier frequencies for wireless communication in a wireless local area network. In some implementations, more particularly, it relates to beamforming training operations that support wireless communication at carrier frequencies above 7 GHz. In some aspects, a beamforming initiator may initiate a beamforming training operation by transmitting, respectively, N beamforming training (BFT) packets in several (N) TX beam directions at a carrier frequency above 7 GHz. A beamforming responder receives one or more 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, the beamforming responder may simultaneously train its RX antenna for RX beamforming while the beamforming initiator trains its TX antenna. In some other aspects, the beamforming responder may train its RX antenna after the beamforming initiator has trained its TX antenna.

Description

Technical Field

[0001] (Cross - Reference to Related Applications)

[0001] This patent application claims priority to U.S. Patent Application No. 17 / 746,623, filed May 17, 2022, by Yang et al., entitled "60 GHZ BEAM MANAGEMENT FOR WIRELESS LOCAL AREA NETWORKS (WLANS)", which has been assigned to the assignee of this specification and is hereby expressly incorporated herein by reference.

[0002]

[0002] The present disclosure generally relates to wireless communication, and more specifically, to 60 GHz beam management techniques for wireless local area networks (WLANs).

Background Art

[0003]

[0003] 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 called stations (STAs). The basic building block of a WLAN compliant with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard family is a basic service set (BSS) managed by an AP. Each BSS is identified by a basic service set identifier (BSSID) advertised 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.

[0004]

[0004] Many existing WLAN communication protocols are designed for wireless communication on carrier frequencies below 7 GHz (such as the 2.4 GHz, 5 GHz, or 6 GHz frequency bands). However, new WLAN communication protocols are being developed to enable extended WLAN communication capabilities (such as higher throughput and wider bandwidth) that require even higher carrier frequencies (such as the 45 GHz or 60 GHz frequency bands). Wireless communication at higher carrier frequencies can suffer from greater phase noise and greater path loss compared to wireless communication at lower carrier frequencies. Therefore, new packet designs and operating modes are needed to support wireless communication on carrier frequencies above 7 GHz since the new WLAN communication protocols enable extended features.

Summary of the Invention

[0005]

[0005] The systems, methods, and devices of the present disclosure each have several innovative aspects, none of which alone carry the desirable attributes disclosed herein.

[0006]

[0006] One innovative aspect of the subject matter described in this disclosure can be implemented as a method of wireless communication. The method can be performed by a wireless communication device and includes transmitting, on a first wireless communication link, N beamforming training (BFT) packets in N transmit (TX) beam directions, respectively, where each of the N BFT packets includes a physical (PHY) preamble carrying respective beam management information indicating the TX beam direction in which the BFT packet is transmitted; receiving, from a response device, a first feedback associated with a first TX beam direction among the N TX beam directions; and transmitting, on the first wireless communication link, a physical layer convergence protocol (PLCP) protocol data unit (PPDU) in the first TX beam direction.

[0007]

[0007] In some aspects, the method may further include associating with a response device via a second wireless communication link, and the N BFT packets are transmitted on the first wireless communication link based on associating with the response 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.

[0008]

[0008] 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 a PPDU type, a training direction, a beam tracking request, the number N of BFT packets, the number of BFT packets remaining to be transmitted, a TX sector identifier (ID) or TX antenna ID associated with the TX beam direction in which the BFT packet is transmitted, 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 a TX sector ID or TX antenna ID indicated by a BFT packet transmitted 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 response device.

[0009]

[0009] In some aspects, the method may further include retransmitting, on a first wireless communication link, N BFT packets in N respective TX beam directions, respectively, based on the number (M) of RX sectors associated with the response device. In such aspects, each of the N BFT packets may be transmitted M times in each respective TX beam direction. In some aspects, the method may further include receiving, on the first wireless communication link, some (K) BFT packets each carrying beam management information indicating each respective beam direction associated with the received BFT packet, measuring the signal power of each of the K received BFT packets, and transmitting, to the response device, a second feedback associated with the received BFT packet having the highest signal power among the measured signal powers. In such aspects, the first feedback may be carried in the K received BFT packets.

[0010]

[0010] In some embodiments, the method may further include receiving, on a first wireless communication link, one or more training signals, each of the one or more training signals being received via a plurality of antennas tuned to respective RX beam directions; measuring the power of each of the received one or more training signals; and receiving, via the plurality of antennas tuned to the RX beam direction of the training signal having the highest signal power among the measured signal powers, a PPDU from a response device. In some implementations, each of the plurality of training signals may represent a respective PPDU. In some other implementations, each of the plurality of training signals may represent a respective training (TRN) field of the same PPDU.

[0011]

[0011] Another innovative aspect of the subject matter described in this disclosure may be implemented in a wireless communication device. In some implementations, the wireless communication device includes at least one memory and at least one processor communicatively coupled to the at least one memory and configured to cause the wireless communication device to perform operations including: transmitting a number (N) of BFT packets, each including a PHY preamble carrying respective beam management information indicating the TX beam direction in which a BFT packet is transmitted, in respective (N) TX beam directions; receiving feedback associated with a first TX beam direction among the N TX beam directions from a response device; and transmitting a PPDU in the first TX beam direction.

[0012]

[0012] Another innovative aspect of the subject matter described in this disclosure can be implemented as a method of wireless communication. The method can be performed by a wireless communication device and includes receiving, on a first wireless communication link, several (N) BFT packets, each including a PHY preamble that carries beam management information indicating a respective beam direction associated with the received BFT packet; measuring the signal power of each of the received BFT packets; transmitting, to an initiating device, a first feedback associated with the received BFT packet having the highest signal power among the measured signal powers; and receiving, on the first wireless communication link, a PPDU based on the first feedback.

[0013]

[0013] In some aspects, the method can further include associating with an initiating device via a second wireless communication link, and 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 can operate at a carrier frequency above 7 GHz, and the second wireless communication link can operate at a carrier frequency below 7 GHz.

[0014]

[0014] 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 a PPDU type, a training direction, a beam tracking request, the number of BFT packets transmitted by the starting device, the number of BFT packets remaining to be transmitted, a TX sector ID or TX antenna ID associated with a beam direction, or the number of RX sectors or RX antennas associated with the starting 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 having the highest signal power, an SNR report, or the number of RX sectors or RX antennas associated with the wireless communication device.

[0015]

[0015] In some aspects, the N BFT packets may be received via a plurality of antennas tuned to several (M) RX beam directions. In some implementations, at least one of the N BFT packets is received multiple times based on tuning a plurality of antennas in a plurality of RX beam directions out of the M RX beam directions, respectively. In some aspects, the method may further include transmitting several (K) BFT packets in each of K TX beam directions on a first wireless communication link, receiving, from the starting device, a second feedback associated with a first TX beam direction out of the K TX beam directions, and transmitting a PPDU in the first TX beam direction on the first wireless communication link. In some implementations, the first feedback may be carried in the K transmitted BFT packets.

[0016]

[0016] In some aspects, the method may further include receiving, on a first wireless communication link, one or more training signals, each of the one or more training signals being received via a plurality of antennas tuned to respective RX beam directions; measuring the signal power of each of the received one or more training signals; and receiving, via the plurality of antennas tuned to the RX beam direction of the training signal having the highest measured signal power among the measured signal powers, a PPDU from a starting device. In some implementations, each of the plurality of training signals may represent a respective PPDU. In some other implementations, each of the plurality of training signals may represent a respective TRN field of the same PPDU.

[0017]

[0017] Another innovative aspect of the subject matter described in this disclosure may be implemented in a wireless communication device. In some implementations, the wireless communication device includes at least one memory and at least one processor communicatively coupled to the at least one memory and configured to cause the wireless communication device to perform operations including: receiving several (N) BFT packets each including a PHY preamble carrying beam management information indicating a respective beam direction associated with the received BFT packet; measuring the signal power of each of the received BFT packets; transmitting feedback associated with the received BFT packet having the highest measured signal power to a starting device; and receiving a PPDU based on the feedback.

Brief Description of the Drawings

[0018]

[0018] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.

Figure 1

[0019] Shows a diagram of an exemplary wireless communication network.

Figure 2A

[0020] Shows an exemplary protocol data unit (PDU) that can be used for communication between an access point (AP) and one or more wireless stations (STAs).

Figure 2B

[0021] Shows exemplary fields within the PDU of FIG. 2A.

Figure 3

[0022] Shows an exemplary physical layer convergence protocol (PLCP) protocol data unit (PPDU) that can be used for communication between an AP and one or more STAs.

Figure 4

[0023] Shows a block diagram of an exemplary wireless communication device.

Figure 5A

[0024] Shows a block diagram of an exemplary AP.

Figure 5B

[0025] Shows a block diagram of an exemplary STA.

Figure 6

[0026] Shows an exemplary communication environment including an AP and an STA according to some implementations.

Figure 7

[0027] Shows an exemplary communication system including an AP multi-link device (MLD) and a non-AP MLD according to some implementations.

Figure 8

[0028] Shows a sequence diagram illustrating exemplary multi-link communication between an AP and an STA according to some implementations.

Figure 9A

[0029] Shows a timing diagram illustrating an exemplary process for training an AP and an STA for transmission (TX) beamforming and reception (RX) beamforming, respectively, according to some implementations.

Figure 9B

[0030] A timing diagram showing an exemplary process for training an AP and a STA for RX beamforming and TX beamforming, respectively, according to some implementations is shown.

Figure 10A

[0031] A timing diagram showing an exemplary process for training an AP and a STA for TX beamforming according to some implementations is shown.

Figure 10B

[0032] A timing diagram showing an exemplary process for training an AP and a STA for RX beamforming according to some implementations is shown.

Figure 10C

[0033] Another timing diagram showing an exemplary process for training an AP and a STA for RX beamforming according to some implementations is shown.

Figure 11

[0034] Another timing diagram showing an exemplary process for training an AP and a STA for TX beamforming according to some implementations is shown.

Figure 12

[0035] A block diagram of an exemplary TX processing chain for a wireless communication device according to some implementations is shown.

Figure 13A

[0036] An exemplary PPDU formatted according to the legacy PPDU format is shown.

Figure 13B

[0037] An exemplary up-clocked PPDU based on the PPDU format shown in FIG. 13A according to some implementations is shown.

Figure 13C

[0038] Another exemplary up-clocked PPDU based on the PPDU format shown in FIG. 13A according to some implementations is shown.

Figure 14A

[0039] An exemplary PPDU formatted according to the legacy PPDU format is shown.

Figure 14B

[0040] Shows an exemplary up - clocked PPDU based on the PPDU format shown in FIG. 14A according to some implementations.

Figure 14C

[0041] Shows another exemplary up - clocked PPDU based on the PPDU format shown in FIG. 14A according to some implementations.

Figure 15A

[0042] Shows an exemplary PPDU formatted according to the legacy PPDU format.

Figure 15B

[0043] Shows an exemplary up - clocked PPDU based on the PPDU format shown in FIG. 15A according to some implementations.

Figure 16

[0044] Shows a timing diagram illustrating an exemplary beamforming training operation between an AP and a STA via an anchor link and a directional link according to some implementations.

Figure 17A

[0045] Shows a timing diagram illustrating an exemplary beamforming training operation between an AP and a STA via an anchor link and a directional link according to some implementations.

Figure 17B

[0046] Shows another timing diagram illustrating an exemplary beamforming training operation between an AP and a STA via an anchor link and a directional link according to some implementations.

Figure 18

[0047] Shows a flowchart illustrating an exemplary process for wireless communication that supports 60 GHz beam management for wireless local area networks (WLANs).

Figure 19

[0048] Shows a flowchart illustrating an exemplary process for wireless communication that supports 60 GHz beam management for a WLAN.

Figure 20

[0049] Shows a block diagram of an exemplary wireless communication device according to some implementations.

Figure 21

[0050] FIG. 2 shows a block diagram of an exemplary wireless communication device according to some implementations.

[0019]

[0051] Like reference numerals and designations in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE INVENTION

[0020]

[0052] The following description is directed to several implementations for the purpose of describing 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 many different ways. The described implementations can be realized in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals, in accordance with, among other things, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, IEEE 802.15 standards, Bluetooth® standards defined by the Bluetooth Special Interest Group (SIG), or the Long Term Evolution (LTE), 3G, 4G, or 5G (New Radio (NR)) standards published by the 3rd Generation Partnership Project (3GPP). The described implementations can be realized in any device, system, or network capable of transmitting and receiving RF signals in accordance with one or more of the following techniques or technologies, namely, 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 implementation forms can 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.

[0021]

[0053] As described above, the new WLAN communication protocol has been developed to enable enhanced features for wireless communication at carrier frequencies above 7 GHz (such as in the 60 GHz or 45 GHz frequency bands). However, wireless communication at higher carrier frequencies can suffer from greater phase noise and path loss compared to wireless communication at lower carrier frequencies. Aspects of the present disclosure recognize that analog beamforming (using multiple antenna elements) can mitigate the effects of path loss and achieve a greater wireless communication range at carrier frequencies above 7 GHz. Analog beamforming is a wireless communication technique in which a transmitting device and a receiving device can adjust the gains and phases of their transmit (TX) and receive (RX) antenna elements to achieve directivity in wireless communication. For example, the transmitting device can synchronize a set of TX antennas (referred to as "TX beamforming") to concentrate the energy of the transmitted signal in a particular direction. Similarly, the receiving device can synchronize a set of RX antennas (referred to as "RX beamforming") to concentrate the energy of the received signal in a particular direction. When TX beamforming is used in combination with RX beamforming, an optimal beamforming gain (such as may be required to overcome path loss in the 60 GHz frequency band) can be achieved. The process by which the transmitting device and the receiving device synchronize their antennas for beamforming is referred to as "beamforming training."

[0022]

[0054] Various aspects generally relate to increasing carrier frequencies for wireless communication in a WLAN, and more particularly to beamforming training operations that support wireless communication 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 transmitting N beamforming training (BFT) packets in N TX beam directions, respectively, where each of the N BFT packets includes a physical layer (PHY) preamble carrying respective beam management information indicating the TX beam direction in which the BFT packet is transmitted. A beamforming responder (such as an 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 having the highest received signal power. In some aspects, the beamforming responder may simultaneously train its RX antenna for RX beamforming while the beamforming initiator trains its TX antenna for TX beamforming. In such aspects, the beamforming responder may tune its RX antenna in M RX beam directions, and the beamforming initiator may retransmit the 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 has trained its TX antenna for TX beamforming. In such aspects, the beamforming responder may tune its RX antenna in M RX beam directions when the beamforming initiator transmits M training sequences, respectively, in the TX beam direction indicated by the feedback.

[0023]

[0055] One or more of the following potential advantages may be realized by certain implementations of the subject matter described in this disclosure. By signaling beam management parameters in the PHY preamble of BFT packets, aspects of the present disclosure can leverage existing WLAN packet formats and hardware to support wireless communication at carrier frequencies above 7 GHz. Training the TX antenna of the beamforming initiator and the RX antenna of the beamforming responder simultaneously relaxes the RX sensitivity requirements at the beamforming responder (due to the combined TX and RX beamforming gain), but requires a significant amount of training overhead (N BFT packets for training the TX antenna of the beamforming initiator and the RX antenna of the beamforming responder, etc.). 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 higher RX sensitivity at the beamforming responder when training the TX antenna of the beamforming initiator (due to the lack of RX beamforming). * M BFT packets, etc.). 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 higher RX sensitivity at the beamforming responder when training the TX antenna of the beamforming initiator (due to the lack of RX beamforming).

[0024]

[0056] FIG. 1 shows a block diagram of an exemplary wireless communication network 100. According to some aspects, wireless communication network 100 may be an example of a wireless local area network (WLAN), such as a Wi-Fi network (also referred to hereinafter as WLAN 100). For example, WLAN 100 may be a network that implements at least one of the IEEE 802.11 family of wireless communication protocol standards (such as those defined in the IEEE 802.11-2020 specification or a revised version thereof, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be). WLAN 100 may include a number of wireless communication devices, such as access point (AP) 102 and multiple stations (STAs) 104. Although only one AP 102 is shown, WLAN network 100 may include multiple APs 102.

[0025]

[0057] Each of the STAs 104 may be referred to as, among other things, 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. The STA 104 may represent various devices, such as a mobile phone, a personal digital assistant (PDA), other handheld devices, a netbook, a notebook computer, a tablet computer, a laptop, a display device (e.g., in particular, a TV, a computer monitor, a navigation system), a music device or other audio device or stereo device, a remote control device ("remote"), a printer, a kitchen appliance or other household appliance, a key fob (e.g., for a passive keyless entry and start (PKES) system), etc.

[0026]

[0058] A single associated set of AP102 and STA104 may be referred to as a basic service set (BSS) managed by each AP102. FIG. 1 additionally shows an exemplary coverage area 108 of an AP102 that may represent the basic service area (BSA) of the WLAN100. A BSS may be identified to a user by a service set identifier (SSID) and to other devices by a basic service set identifier (BSSID), which may be the medium access control (MAC) address of the AP102. The AP102 enables any STA104 within the wireless range of the AP102 to "associate" or re-associate with the AP102 in order to establish or maintain a respective communication link 106 (hereinafter also referred to as "Wi-Fi link") with the AP102 by periodically broadcasting a beacon frame ("beacon") containing the BSSID. For example, the beacon may include identification information of the primary channel used by each AP102 and a timing synchronization function for establishing or maintaining timing synchronization with the AP102. The AP102 may provide access to an external network to various STA104 in the WLAN via each communication link 106.

[0027]

[0059] To establish a communication link 106 with an AP102, each of the STAs 104 is configured to perform a passive scan operation or an active scan operation ("scan") on a frequency channel within one or more frequency bands (e.g., a 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz band). To perform a passive scan, the STA 104 listens for beacons, which are transmitted by respective AP102s at periodic time intervals called target beacon transmission times (TBTTs), measured in time units (TUs), where 1 TU may be equal to 1024 microseconds (μs). To perform an active scan, the STA 104 generates probe requests and transmits them continuously on each channel to be scanned, and listens for probe responses from the AP102s. Each STA 104 may be configured to identify or select an AP102 to associate with based on scan information obtained through passive or active scanning, and perform an authentication operation and an association operation to establish a communication link 106 with the selected AP102. The AP102 assigns an association identifier (AID) to the STA 104 upon completion of the association operation, and the AP102 uses it to track the STA 104.

[0028]

[0060] As a result of the increasing pervasiveness of wireless networks, STA104 may have the opportunity to select one of many BSSs within the range of the STA, or to select from among a plurality of APs102 that together form an extended service set (ESS) that includes multiple connected BSSs. An extended network station associated with WLAN100 may be connected to a wired or wireless distribution system that may enable multiple APs102 to be connected within such an ESS. Thus, STA104 can be covered by two or more APs102 and can be associated with different APs102 at different times for different transmissions. Additionally, after association with an AP102, STA104 can also be configured to periodically scan its surroundings to find a more suitable AP102 to associate with. For example, STA104, which is moving relative to its associated AP102, may perform a "roaming" scan to find another AP102 with more desirable network characteristics, such as a larger received signal strength indicator (RSSI) or a reduced traffic load.

[0029]

[0061] In some cases, STA104 may form a network without involving AP102 or other devices other than STA104 itself. An example of such a network is an ad hoc network (or a wireless ad hoc network). An ad hoc network may alternatively be referred to as a mesh network or a peer-to-peer (P2P) network. In some cases, an ad hoc network may be implemented within a larger wireless network such as WLAN100. In such an implementation, STA104 may be able to communicate with each other via AP102 using communication link 106, but STA104 can also communicate directly with each other via direct wireless link 110. Additionally, two STA104 may communicate via direct communication link 110 regardless of whether both STA104 are associated with the same AP102 and served by the same AP102. In such an ad hoc system, one or more of STA104 may assume the role fulfilled by AP102 within the BSS. Such STA104 may be referred to as a group owner (GO) and may be able to coordinate transmissions within the ad hoc network. Examples of direct wireless link 110 include Wi-Fi Direct connections, connections established by using Wi-Fi Tunneled Direct Link Setup (TDLS) links, and other P2P group connections.

[0030]

[0062] AP102 and STA104 can function and communicate (via their respective communication links 106) in accordance with the IEEE 802.11 family of wireless communication protocol standards (including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be, as defined in the IEEE 802.11-2016 specification or a revision thereof). These standards define the WLAN wireless and baseband protocols for the PHY layer and the Medium Access Control (MAC) layer. AP102 and STA104 transmit and receive wireless communication (hereinafter also referred to as "Wi-Fi communication") with each other in the form of Physical Layer Convergence Protocol (PLCP) Protocol Data Units (PPDUs). AP102 and STA104 in WLAN100 may transmit PPDUs via an unlicensed spectrum, which may be a portion of the spectrum including frequency bands conventionally used by Wi-Fi technologies such as the 2.4 GHz band, 5 GHz band, 60 GHz band, 3.6 GHz band, and 700 MHz band. Some implementations of AP102 and STA104 described herein may also communicate within other frequency bands, such as the 6 GHz band, which can support both licensed and unlicensed communication. AP102 and STA104 may also be configured to communicate via other frequency bands, such as shared license frequency bands, for which multiple operators may have permission to operate within the same or overlapping frequency bands.

[0031]

[0063] Each frequency band may include a plurality of sub-bands or frequency channels. For example, PPDUs compliant with the IEEE802.11n, 802.11ac, 802.11ax, and 802.11be standard revisions can be transmitted via the 2.4GHz, 5GHz, or 6GHz bands, each of which is divided into a plurality of 20MHz channels. Therefore, these PPDUs are transmitted via physical channels having a minimum bandwidth of 20MHz, but larger channels can be formed through channel bonding. For example, a PPDU can be transmitted via a physical channel having a bandwidth of 40MHz, 80MHz, 160MHz, or 320MHz by bonding a plurality of 20MHz channels together.

[0032]

[0064] Each PPDU is a composite structure that includes a PHY preamble and a payload in the form of a PHY service data unit (PSDU). The information provided within the preamble may be used by the receiving device to decode subsequent data within the PSDU. In cases where a PPDU is transmitted via a bonded channel, the preamble field may be replicated and transmitted in each of the plurality of component channels. The PHY preamble may include both a legacy portion (or "legacy preamble") and a non-legacy portion (or "non-legacy preamble"). The legacy preamble can be used, among other things, for packet detection, automatic gain control, and channel estimation. The legacy preamble can also generally be used to maintain compatibility with legacy devices. The format, coding, and information provided in the non-legacy portion of the preamble are based on the specific IEEE802.11 protocol that will be used to transmit the payload.

[0033]

[0065] FIG. 2A shows an exemplary protocol data unit (PDU) 200 that can be used for wireless communication between the AP 102 and one or more STAs 104. 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 that 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 in accordance with the IEEE 802.11a wireless communication protocol standard. The preamble 202 can also include a non-legacy portion that includes one or more non-legacy fields 212 that comply with an IEEE wireless communication protocol, such as, for example, the IEEE 802.11ac, 802.11ax, 802.11be, or later wireless communication protocol standards.

[0034]

[0066] L-STF206 generally enables a receiving device to perform automatic gain control (AGC), coarse timing estimation, and frequency estimation. L-LTF208 generally enables a receiving device to perform fine timing estimation and frequency estimation, and also enables an initial estimation of the wireless channel to be performed. L-SIG210 generally enables a receiving device to determine the duration of a PDU and use the determined duration in order to avoid transmitting at the beginning of the PDU. For example, L-STF206, L-LTF208, and L-SIG210 may be modulated according to a binary phase shift keying (BPSK) modulation scheme. Payload 204 may be modulated according to a BPSK modulation scheme, a quadrature BPSK (Q-BPSK) modulation scheme, a quadrature amplitude modulation (QAM) modulation scheme, or another suitable modulation scheme. Payload 204 may include a PSDU that includes a data field (DATA) 214, and data field (DATA) 214 may carry upper layer data in the form of, for example, media access control (MAC) protocol data units (MPDUs) or aggregated MPDUs (A-MPDUs).

[0035]

[0067] Figure 2B shows an exemplary L-SIG 210 within the PDU 200 of FIG. 2A. The 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. The data rate field 222 indicates the data rate (note that the data rate indicated within the data rate field 212 may not be the actual data rate of the data carried within the payload 204). The length field 226 indicates the length of the packet, for example, in units of symbols or bytes. The parity bit 228 can be used to detect bit errors. The tail field 230 includes tail bits that can be used by the receiving device to terminate the operation of a decoder (e.g., a Viterbi decoder). The receiving device can utilize the data rate and length indicated within the data rate field 222 and the length field 226 to determine the duration of the packet, for example, in units of microseconds (μs) or other time units.

[0036]

[0068] FIG. 3 shows an exemplary PPDU 300 that can be used for communication between the 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 a plurality of 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 prior to an accompanying MPDU 316 that includes the data portion ("payload" or "frame body") of the MPDU frame 310. Each MPDU frame 310 may 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 a plurality of A-MSDU subframes 324. Each A-MSDU subframe 324 includes a corresponding MSDU 330 preceded by a subframe header 328 and optionally followed by padding bits 332.

[0037]

[0069] Referring again to the MPDU frame 310, the MAC delimiter 312 serves as a marker for the start of the associated MPDU 316 and may indicate the length of the associated MPDU 316. The MAC header 314 may include a plurality of fields containing information that defines or indicates the characteristics or attributes of the data encapsulated within the frame body 316. The MAC header 314 includes a duration field that indicates the duration that continues from the end of the PPDU to at least the end of an acknowledgment (ACK) or Block ACK (BA) of the PPDU that is to be transmitted by the receiving wireless communication device. The use of the duration field helps to reserve the wireless medium for the indicated duration and enables 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 within 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 further include a frame control field containing control information. The frame control field can specify the frame type, for example, a data frame, a control frame, or a management frame.

[0038]

[0070] FIG. 4 shows a block diagram of an exemplary wireless communication device 400. In some implementations, the wireless communication device 400 can be an example of a device used in a STA such as one of the STAs 104 described with reference to FIG. 1. In some implementations, the wireless communication device 400 can be an example of a device used in an AP such as the AP 102 described with reference to FIG. 1. The wireless communication device 400 is capable of transmitting (or outputting for transmission) and receiving wireless communication (e.g., in the form of wireless packets). For example, the wireless communication device can transmit 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) compliant with the IEEE 802.11 wireless communication protocol standards as defined in the IEEE 802.11-2016 specification or a revision thereof, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be.

[0039]

[0071] The wireless communication device 400 can be a chip, system on chip (SoC), chipset, package, or device that includes one or more modems 402, such as a Wi-Fi (IEEE 802.11 compliant) modem, or can include them. In some implementations, one or more modems 402 (collectively referred to as "modems 402") additionally include a WWAN modem (e.g., a 3GPP 4G LTE or 5G compliant modem). In some implementations, the wireless communication device 400 also includes one or more radios 404 (collectively referred to as "radios 404"). In some implementations, the wireless communication device 406 further includes one or more processors, processing blocks, or processing elements 406 (collectively referred to as "processors 406") and one or more memory blocks or elements 408 (collectively referred to as "memory 408").

[0040]

[0072] The modem 402 can include intelligent hardware blocks or devices, such as, for example, an application-specific integrated circuit (ASIC), among other things. The modem 402 is generally configured to implement the PHY layer. For example, the modem 402 is configured to output a modulated packet to the radio 404 for transmission via a wireless medium by modulating the packet. The modem 402 is similarly configured to obtain the modulated packet received by the radio 404 and demodulate the packet to provide a demodulated packet. In addition to the modulator and demodulator, the modem 402 may further include a digital signal processing (DSP) circuit, an automatic gain control (AGC), an encoder, a decoder, a multiplexer, and a demultiplexer. For example, during the transmit mode, the data obtained from the processor 406 is provided to the encoder, which encodes the data to provide encoded bits. The encoded bits are then mapped to points within a modulation constellation (using the selected MCS) to provide modulated symbols. The modulated symbols can then be mapped to N SS number of spatial streams or N STS number of spatio-temporal streams. The modulated symbols in each spatial or spatio-temporal stream are then multiplexed, converted via an inverse fast Fourier transform (IFFT) block, and subsequently provided to the DSP circuit for Tx window processing and filtering. The digital signal can then be provided to a digital-to-analog converter (DAC). The resulting analog signal can then be provided to a frequency upconverter and ultimately to the radio 404. In an implementation with beamforming, the modulated symbols in each spatial stream are precoded via a steering matrix before being provided to the IFFT block.

[0041]

[0073] While in the receive mode, the digital signal received from the radio 404 is provided to the DSP circuit, which is configured to acquire the received signal, for example, by detecting the presence of the signal and estimating the initial timing and frequency offset. The DSP circuit configuration is further configured to digitally condition the digital signal, for example, using channel (narrowband) filtering, analog impairment adjustment (such as correcting I / Q imbalance), and applying digital gain to finally obtain a narrowband signal. The output of the DSP circuit may then be supplied to the AGC, which is configured to use information extracted from the digital signal within one or more received training fields, for example, to determine an appropriate gain. The output of the DSP circuit is also coupled to a demodulator, which is configured to extract the modulated symbols from the signal and calculate, for example, the logarithm likelihood ratios (LLRs) 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 of the spatial streams are then supplied 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.

[0042]

[0074] The radio 404 generally 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 the RF receiver may each include various DSP circuits including at least one power amplifier (PA) and at least one low-noise amplifier (LNA). Next, the RF transmitter and the RF receiver may be coupled to one or more antennas. For example, in some implementations, the wireless communication device 400 may include or be coupled to a plurality of transmit antennas (each with a corresponding transmit chain) and a plurality of receive antennas (each with a corresponding receive chain). The symbols output from the modem 402 are provided to the radio 404, and then the radio 404 transmits the symbols via the coupled antennas. Similarly, the symbols received via the antennas are acquired by the radio 404, and then the radio 404 provides the symbols to the modem 402.

[0043]

[0075] Processor 406 can include intelligent hardware blocks or devices 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 field programmable gate array (FPGA), or any combination thereof designed to perform the functions described herein, such as programmable logic devices (PLDs), discrete gate or transistor logic, discrete hardware components. Processor 406 processes information received via radio 404 and modem 402 and processes information to be output via modem 402 and radio 404 for transmission over a wireless medium. For example, processor 406 may implement a control plane and a MAC layer 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, among other operations or techniques, frame coding and decoding, spatial multiplexing, space-time block coding (STBC), beamforming, and OFDMA resource allocation. In some implementations, processor 406 can generally control modem 402 to cause the modem to perform the various operations described above.

[0044]

[0076] Memory 408 can include a tangible storage medium such as a random-access memory (RAM), a read-only memory (ROM), or a combination thereof. Memory 408 can also store non-transitory processor or computer-executable software (SW) code that, when executed by processor 406, causes the processor to perform various operations described herein for wireless communication, including generation, transmission, reception, and interpretation of MPDUs, frames, or packets. For example, the various functions of the components disclosed herein, or the various blocks or steps of the methods, operations, processes, or algorithms disclosed herein, can be implemented as one or more modules of one or more computer programs.

[0045]

[0077] FIG. 5A shows a block diagram of an exemplary AP502. For example, AP502 can be an exemplary implementation of AP102 described with reference to FIG. 1. AP502 includes a wireless communication device (WCD) 510 (although AP502 itself may also generally be referred to as a wireless communication device as used herein). For example, wireless communication device 510 can be an exemplary implementation of wireless communication device 400 described with reference to FIG. 4. AP502 also includes a plurality of antennas 520 coupled to wireless communication device 510 for transmitting and receiving wireless communication. In some implementations, AP502 additionally includes an application processor 530 coupled to wireless communication device 510 and a memory 540 coupled to application processor 530. AP502 further includes at least one external network interface 550 that enables AP502 to communicate with a core network or a backhaul network so as to access an external network including the Internet. For example, 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). Some of the above-described components can communicate directly or indirectly with some of the other components via at least one bus. AP502 further includes a housing that includes at least a portion of wireless communication device 510, application processor 530, memory 540, and antennas 520 and external network interface 550.

[0046]

[0078] FIG. 5B shows a block diagram of an exemplary STA504. For example, STA504 may be an exemplary implementation of STA104 described with reference to FIG. 1. STA504 includes a wireless communication device 515 (although STA504 itself may also be commonly referred to as a wireless communication device as used herein). For example, wireless communication device 515 may be an exemplary implementation of wireless communication device 400 described with reference to FIG. 4. STA504 also includes one or more antennas 525 coupled to wireless communication device 515 for transmitting and receiving wireless communication. Additionally, STA504 includes an application processor 535 coupled to wireless communication device 515 and a memory 545 coupled to application processor 535. In some implementations, STA504 further includes a user interface (UI) 555 (such as a touch screen or keypad) and a display 565, and display 565 may be integrated with UI555 to form a touch screen display. In some implementations, STA504 may further include one or more sensors 575, such as one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors. Some of the above-described components can communicate directly or indirectly with some of the other components via at least one bus. STA504 further includes a housing that includes at least a portion of wireless communication device 515, application processor 535, memory 545, and antennas 525, UI555, and display 565.

[0047]

[0079] As described above, a new WLAN communication protocol has been developed to enable enhanced features for wireless communication at carrier frequencies above 7 GHz (such as in the 60 GHz or 45 GHz frequency bands). However, wireless communication at higher carrier frequencies can suffer from greater phase noise and path loss compared to wireless communication at lower carrier frequencies. Aspects of the present disclosure recognize that analog beamforming (using a number of antenna elements) can mitigate the effects of path loss and achieve a greater wireless communication range at carrier frequencies above 7 GHz. Analog beamforming is a wireless communication technique in which a transmitting device and a receiving device can adjust the gains and phases of their TX and RX antenna elements to achieve directivity in wireless communication. For example, a transmitting device can tune a set of TX antennas (referred to as “TX beamforming”) to concentrate the energy of a transmitted signal in a particular direction. Similarly, a receiving device can tune a set of RX antennas (referred to as “RX beamforming”) to concentrate the energy of a received signal in a particular direction. When TX beamforming is used in combination with RX beamforming, an optimal beamforming gain (such as may be required to overcome path loss in the 60 GHz frequency band) can be achieved. The process by which a transmitting device and a receiving device tune their antennas for beamforming is referred to as “beamforming training”.

[0048]

[0080] Various aspects generally relate to increasing the carrier frequency for wireless communication in a WLAN, and more particularly to beamforming training operations that support wireless communication 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 transmitting N beamforming training (BFT) packets in N TX beam directions, respectively, where each of the N BFT packets includes a PHY preamble carrying respective beam management information indicating the TX beam direction in which the BFT packet is transmitted. A beamforming responder (such as an STA) may receive one or more of the N BFT packets and provide feedback to the beamforming initiator indicating the TX beam direction associated with the BFT packet having the highest received signal power. In some aspects, the beamforming responder may simultaneously train its RX antenna for RX beamforming while the beamforming initiator trains its TX antenna for TX beamforming. In such aspects, the beamforming responder may tune its RX antenna in M RX beam directions, and the beamforming initiator may retransmit the 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 has trained its TX antenna for TX beamforming. In such aspects, the beamforming responder may tune its RX antenna in M RX beam directions when the beamforming initiator transmits M training sequences, respectively, in the TX beam direction indicated by the feedback.

[0049]

[0081] To achieve one or more of the following potential advantages, certain implementations of the subject matter described in this disclosure may be implemented. By signaling beam management parameters in the PHY preamble of BFT packets, aspects of the present disclosure can leverage existing WLAN packet formats and hardware to support wireless communication at carrier frequencies above 7 GHz. Training the TX antenna of the beamforming initiator and the RX antenna of the beamforming responder simultaneously relaxes the RX sensitivity requirements at the beamforming responder (due to the combined TX and RX beamforming gain), but requires a significant amount of training overhead (N BFT packets for training the TX antenna of the beamforming initiator and the RX antenna of the beamforming responder, etc.). * M BFT packets, etc.). 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 higher RX sensitivity at the beamforming responder when training the TX antenna of the beamforming initiator (due to the lack of RX beamforming).

[0050]

[0082] FIG. 6 shows an exemplary communication environment 600 including an AP610 and a STA620 according to some implementations. In some implementations, AP610 can be an example of either AP102 or 502 of FIGS. 1 and 5A, respectively. In some implementations, STA620 can be an example of either STA104 or 504 of FIGS. 1 and 5B, respectively. In the example of FIG. 6, AP610 is associated with a BSS that supports wireless communication at a carrier frequency above 7 GHz (such as in the 60 GHz frequency band).

[0051]

[0083] In some implementations, AP610 may use beamforming to communicate over longer distances and mitigate the effects of path loss at carrier frequencies above 7 GHz. For example, AP610 may transmit packets or PPDUs via several antenna sectors T1 - T7 configured or tuned for TX beamforming (also referred to as "TX sectors"). The antenna elements associated with each TX sector are weighted such that the energy radiated by each antenna element is combined along a specific beam direction. Thus, each of TX sectors T1 - T7 can be tuned to its respective TX beam direction. For simplicity, AP610 is shown as including seven TX sectors T1 - T7. However, in an actual implementation, AP610 may include fewer or more TX sectors than those shown in FIG. 6.

[0052]

[0084] In some implementations, STA620 may also use beamforming to communicate over carrier frequencies above 7 GHz. For example, STA620 may receive packets or PPDUs via several antenna sectors R1 - R7 configured or tuned for RX beamforming (also referred to as "RX sectors"). The antenna elements associated with each RX sector are weighted such that the energy received by each antenna element is combined along a specific beam direction. Thus, each of RX sectors R1 - R7 can be tuned to its respective RX beam direction. For simplicity, STA620 is shown as including seven RX sectors R1 - R7. However, in an actual implementation, STA620 may include fewer or more RX sectors than those shown in FIG. 6.

[0053]

[0085] In some aspects, the AP610 may perform a beamforming training operation with the STA620 to determine TX and RX beam directions that optimize the beamforming gain for wireless communication between the AP610 and the STA620. For example, the AP610 may transmit respective beamforming training (BFT) packets via each of the TX sectors T1 - T7 and train its TX antenna for TX beamforming by receiving feedback from the STA620 indicating the TX sector associated with the highest TX beamforming gain. Further, the STA620 may listen for respective BFT packets from the AP610 via each of the RX sectors R1 - R7 and train its RX antenna for RX beamforming by determining the RX sector associated with the highest RX beamforming gain based on the received BFT packets. In some implementations, the AP610 may further train its RX antenna (not shown for simplicity) for RX beamforming, and the STA620 may further train its TX antenna (not shown for simplicity) for TX beamforming.

[0054]

[0086] Beamforming can help mitigate path loss at carrier frequencies above 7 GHz, but the directivity of the beamformed signal (or "beam") presents challenges for BSS discovery and association. As shown in FIG. 6, AP610 and STA620 can achieve an optimized beamforming gain for the beam transmitted via the TX sector T1 (of AP610) and received via the RX sector R7 (of STA620). In contrast, a beam transmitted by AP610 in other TX beam directions (such as via any of TX sectors T2 - T7) may not be able to reach STA620. The direction of STA620 is generally not known to AP610 during the BSS discovery and association operations that rely on packet exchange between AP610 and STA620. In some aspects, AP610 can transmit a beam in each of its TX beam directions before performing the beamforming training operation so that at least one of the beams reaches STA620. In some implementations, such a beam can carry management or control information that can be used to establish or maintain communication with STA620 (such as for BSS discovery or association).

[0055]

[0087] Repeatedly transmitting the same management or control frame via each of TX sectors T1 - T7 can consume significant overhead and result in inefficient use of the wireless medium. Existing versions of the IEEE802.11 standard define a BSS discovery protocol for carrier frequencies below 7 GHz (also referred to as the "sub - 7GHz" frequency band), whereby an AP advertises its BSS in management frames (such as beacons or probe responses) transmitted omnidirectionally. Any STA within the coverage area of the AP can receive such a management frame and request to associate with (or maintain the association with) the BSS. Thus, aspects of the present disclosure recognize that BSS discovery and association operations can be performed more effectively in the sub - 7GHz frequency band than at carrier frequencies above 7 GHz.

[0056]

[0088] Aspects of the present disclosure further recognize that some wireless communication devices (including APs and STAs) are capable of multi-link operation (MLO). Devices supporting MLO may be referred to as multi-link devices (MLDs). For example, an AP MLD may include multiple APs, each configured to communicate with a non-AP MLD (also referred to as a "STA MLD") on a respective one of multiple communication links. Similarly, a non-AP MLD may include multiple STAs, each configured to communicate on a respective one of multiple communication links associated with an AP MLD. In some 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 can 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 can communicate via a directional beam on a wireless communication link operating at a carrier frequency above 7 GHz.

[0057]

[0089] FIG. 7 shows an exemplary 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 an example of any one of the APs 102, 502, or 610 of FIGS. 1, 5A, and 6, respectively. In some implementations, the non-AP MLD 720 may be an example of any one of the STAs 104, 504, or 620 of FIGS. 1, 5B, and 6, respectively.

[0058]

[0090] AP MLD710 includes a plurality of APs 712 and 714 associated with (or operating on) communication links 702 and 704, respectively. In the example of FIG. 7, AP MLD710 is shown to include two APs. However, in some implementations, AP MLD710 may include fewer or more APs than the APs illustrated in FIG. 7. In some aspects, APs 712 and 714 may share a common association context (through AP MLD710). APs 712 and 714 may also establish their respective communication links 702 and 704 on different frequency bands. In some implementations, AP712 can operate at a carrier frequency below 7 GHz (such as in any of the frequency bands of 2.4 GHz, 5 GHz, or 6 GHz), and AP714 can operate at a carrier frequency above 7 GHz (such as in the frequency band of 60 GHz or 45 GHz).

[0059]

[0091] Non-AP MLD720 includes a plurality of STAs 722 and 724 that may be configured to communicate on communication links 702 and 704, respectively. In some implementations, STA722 can operate at a carrier frequency below 7 GHz (such as in any of the frequency bands of 2.4 GHz, 5 GHz, or 6 GHz), and STA724 can operate at a carrier frequency above 7 GHz (such as in the frequency band of 60 GHz or 45 GHz). In the example of FIG. 7, non-AP MLD720 is shown to include only two STAs. However, in some implementations, non-AP MLD720 may include fewer or more STAs than the STAs illustrated in FIG. 7. Existing versions of the IEEE802.11 standard define several modes in which a non-AP MLD can operate. The various operating modes depend on the number of wireless radios associated with the non-AP MLD and the ability of the non-AP MLD to communicate simultaneously (such as by transmitting or receiving) on multiple communication links.

[0060]

[0092] In some implementations, the non-AP MLD 720 may include a single radio or, alternatively, may 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 can simultaneously listen for certain types of packets (such as buffer status report poll (BSRP) frames or multi-user request-to-send (MU-RTS) frames) on multiple links, but can transmit or receive on only one of the links at any given time. For example, STAs 722 and 724 can simultaneously listen on their respective links 702 and 704 during the listen 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 can listen on and transmit or receive on only one communication link at any given time. For example, one of STAs 722 or 724 must be in a power-saving mode whenever the other STA is active.

[0061]

[0093] In some other implementations, the non-AP MLD 720 may include multiple radios and may be capable of simultaneous communication on each of the links 702, 704. In such implementations, the non-AP MLD 720 may operate in a multi-link multi-radio (MLMR) simultaneous transmit and receive (STR) mode or a multi-link multi-radio non-STR (NSTR) mode. The non-AP MLD operating in the MLMR STR mode can transmit and receive simultaneously on multiple communication links. For example, the STA 722 may transmit or receive on the link 702, while the STA 724 may transmit or receive simultaneously on the link 704. More specifically, such communication may be asynchronous. In other words, the STA 722 may be transmitting on the link 702, while the STA 724 may be receiving on the link 704. In contrast, the non-AP MLD operating in the MLMR NSTR mode can transmit and receive simultaneously on multiple communication links only if such communication is synchronous. For example, the STAs 722 and 724 may transmit simultaneously on the links 702 and 704 and may receive simultaneously on the links 702 and 704. However, while the STA 722 is receiving on the link 702, the STA 724 cannot transmit on the link 704.

[0062]

[0094] Furthermore, in some implementations, the non-AP MLD may include multiple radios, but may be able to communicate simultaneously only on a subset of the links. In such implementations, the non-AP MLD 720 may operate in an enhanced MLMR (eMLMR) mode or a hybrid eMLSR mode. The non-AP MLD operating in the eMLMR mode supports the MLMR STR operation between specific pairs of communication links. For example, STAs 722 and 724 may communicate simultaneously on their respective links 502 and 504 according to the MLMR STR operation mode, but other pairs of STAs associated with the non-AP MLD 720 (not shown for simplicity) may not transmit or receive simultaneously on their respective links (referred to herein as "eMLMR links"). Thus, such other STAs may "pool" their antennas so that each of the STAs can utilize the antennas of the other STAs when transmitting or receiving on one of the eMLMR links. On the other hand, the non-AP MLD operating in the hybrid eMLSR mode supports the MLMR STR operation between some pairs of links and the eMLSR operation between some other pairs of links.

[0063]

[0095] In some embodiments, the AP MLD710 and the non-AP MLD720 can perform various management and control functions (such as BSS discovery or association) on the link 702, and can exchange directional communications on the link 702 based on the management and control functions executed on the link 704. Accordingly, 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 MLD720 may advertise its BSS in a management frame (such as a beacon or a probe response) transmitted omnidirectionally on the anchor link 702. The AP MLD710 can further associate with the non-AP MLD720 via the anchor link 702 based on the BSS information carried in the beacon or the probe response. In some implementations, the AP MLD710 can communicate with the non-AP MLD720 on the directional link 704 based on the association context established on the anchor link 702. More specifically, the AP MLD710 and the non-AP MLD720 can communicate on the directional link 704 using beamforming techniques (as described with reference to FIG. 6).

[0064]

[0096] FIG. 8 shows a sequence diagram 800 illustrating exemplary multi-link communication between an AP810 and an STA820 according to some embodiments. In some embodiments, the AP810 and the STA820 can be examples of the AP MLD710 and the non-AP MLD720 of FIG. 7, respectively. Each of the AP810 and the STA820 can be configured to communicate on a plurality of wireless communication links 802 and 804. For example, referring to FIG. 7, the communication links 802 and 804 can be examples of the communication links 702 and 704, respectively. Accordingly, the link 802 may be an anchor link operating at a carrier frequency below 7 GHz, and the link 804 may be a directional link operating at a carrier frequency above 7 GHz.

[0065]

[0097] In the example of FIG. 8, AP810 and STA820 are initially in a non-associated state. Therefore, AP810 and STA820 can perform BSS discovery on anchor link 802. For example, the AP can transmit on anchor link 802 a management frame (such as a beacon or a probe response) that carries BSS information advertising its BSS. Such a management frame can be transmitted omnidirectionally so that any STA within the coverage area of AP810 can discover the BSS. Upon discovering the BSS, STA820 may request to associate with AP810. Therefore, AP810 and STA820 can perform an association operation via anchor link 802. For example, STA820 can first initiate a low-level authentication exchange with AP810 via anchor link 802. After authentication, STA820 can send an association request to AP810 via anchor link 802. AP810 can complete the association operation by replying with an association response to STA820 via anchor link 802.

[0066]

[0098] Once associated, AP810 can communicate with STA820 via directional link 804. Therefore, wireless communication on directional link 804 (for data transmission, etc.) is effectively coupled to wireless communication on anchor link 802 (for BSS discovery and association, etc.). In some implementations, STA820 (and AP810) can switch between anchor link 802 and directional link 804 using any of the techniques described with reference to FIG. 7. In some aspects, AP810 and STA820 can use beamforming techniques when communicating on directional link 804, for example, to mitigate the impact of path loss for carrier frequencies above 7 GHz. As described with reference to FIG. 6, AP810 can perform a beamforming training operation with STA820 to determine the TX and RX beam directions that optimize the beamforming gain.

[0067]

[0099] In some implementations, AP810 can initiate a beamforming training operation by transmitting respective BFT packets on the directional link 804 via each of its TX sectors, and STA820 can provide feedback to AP810 in response to receiving one or more of the BFT packets. For example, the feedback can indicate which of the BFT packets transmitted by AP810 (or which of AP810's TX sectors) is associated with the highest received signal power. In some other implementations, STA820 can initiate a beamforming training operation by transmitting respective BFT packets on the directional link 804 via each of its TX sectors, and AP810 can provide feedback to STA820 in response to receiving one or more of the BFT packets. For example, the feedback can indicate which of the BFT packets transmitted by STA820 (or which of STA820's TX sectors) 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".

[0068]

[0100] As a result of the beamforming training operation, the beamforming initiator selects the TX beam direction to be used for directional communication with the beamforming responder, and the beamforming responder selects the RX beam direction to be used for directional communication with the beamforming initiator. In some implementations, the beamforming initiator may also select the RX beam direction to be used for directional communication with the beamforming responder, and the beamforming responder may also select the TX beam direction to be used for directional communication with the beamforming initiator. Thus, the AP 810 can communicate with the STA 820 via the directional link 804 using the beam associated with the TX and RX beam directions determined as a result of the beamforming training operation. In some implementations, the AP 810 can further fine-tune its TX or RX beam direction based on real-time communication with the STA 820. In some implementations, the STA 820 can further fine-tune its TX or RX beam direction based on real-time communication with the AP 810.

[0069]

[0101] FIG. 9A shows a timing diagram 900 illustrating an exemplary process for training an AP and a STA for TX beamforming and RX beamforming, respectively, according to some implementations. In some aspects, the training process of FIG. 9A can represent at least a portion of a beamforming training operation that can be performed at a carrier frequency above 7 GHz (such as a directional link). In some implementations, the AP can be an example of any of the AP 610 or 810 of FIGS. 6 and 8, or the AP MLD 710 of FIG. 7. In some implementations, the STA can be an example of any of the STA 620 or 820 of FIGS. 6 and 8, or the non-AP MLD 720 of FIG. 7.

[0070]

[0102] In the example of FIG. 9A, the AP simultaneously trains its TX antennas for TX beamforming, while the STA trains its RX antennas for RX beamforming. More specifically, the training process is performed over a number (M) of beam training intervals 902(1) to 902(M) equal to the number of RX sectors associated with the STA. During each beam training interval 902, the AP transmits N BFT packets in several (N) TX beam directions (T1 to TN), respectively, and the STA attempts to receive (or listen for) the N BFT packets by tuning its RX antennas to a specific RX beam direction. More specifically, the RX antennas associated with the STA are tuned to M RX beam directions (R1 to RM) over the M training intervals 902(1) to 902(M), respectively, and remain tuned to the same RX beam direction during the duration of each beam training interval 902. Each of the TX beam directions may be associated with a respective TX sector of the AP (such as TX sectors T1 to T7 in FIG. 6), and each of the RX beam directions may be associated with a respective RX sector of the STA (such as RX sectors R1 to R7 in FIG. 6).

[0071]

[0103] The first beam training interval 902(1) occurs between times t0 and t1. During the first beam training interval 902(1), the AP performs a TX sector sweep and the STA listens in the R1 beam direction. More specifically, the AP transmits 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 can be used to train the AP's TX or RX sector. Exemplary beam management information may include, among other examples, PPDU type, training direction (TX or RX), beam tracking requirements, number of BFT packets (N), sector identifier (ID), antenna ID, or the number of RX antennas or sectors associated with the AP. Due to the various pairings of R1 and the T1 - TN beam directions, the STA may receive zero or more of the BFT packets transmitted by the AP between times t0 and t1. In some implementations, the STA can measure the signal power of each of the BFT packets (if any) received during the first beam training interval 902(1).

[0072]

[0104] The second beam training interval 902(2) occurs between times t1 and t2. During the second beam training interval 902(2), the AP performs a TX sector sweep and the STA listens in the R2 beam direction. More specifically, the AP transmits 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 can be used to train the AP's TX or RX sector. Exemplary beam management information may include, among other examples, PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (N), sector ID, antenna ID, or the number of RX antennas or sectors associated with the AP. Due to the various pairings of R2 and the T1-TN beam directions, the STA may receive zero or more of the BFT packets transmitted by the AP between times t1 and t2. In some implementations, the STA can measure the signal power of each of the BFT packets (if any) received during the second beam training interval 902(2).

[0073]

[0105] The M-th beam training interval 902(M) occurs between times t3 and t4. During the M-th beam training interval 902(M), the AP performs TX sector sweeping while the STA is listening in the RM beam direction. More specifically, the AP transmits 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 can be used to train the AP's TX or RX sector. Exemplary beam management information may include, among other examples, PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (N), sector ID, antenna ID, or the number of RX antennas or sectors associated with the AP. Due to the various pairings of the RM and T1-TN beam directions, the STA may receive zero or more of the BFT packets transmitted by the AP between times t3 and t4. In some implementations, the STA can measure the signal power of each of the received BFT packets (if any) during the M-th beam training interval 902(M).

[0074]

[0106] The STA compares the measured signal powers of the BFT packets received over the beam training intervals 902(1) to 902(M) and selects the combination of TX and RX beam directions that yields 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) indicating the best TX beam direction to the AP. For example, the feedback may include, among other examples, the best sector ID (such as the sector ID of the AP associated with the best TX beam direction), the 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. Thereafter, the AP can tune its TX antenna to the best TX beam direction, and the STA can tune its RX antenna to the best RX beam direction to exchange directional communication via a directional link.

[0075]

[0107] In some implementations, the AP and the STA may support antenna reciprocity. In other words, 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 for a given wireless communication device. In such implementations, the beamforming training operation may end 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, 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 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 TX beam direction for the STA.

[0076]

[0108] Figure 9B shows a timing diagram 910 illustrating an exemplary process for training an AP and a STA for TX beamforming and RX beamforming, respectively, according to some implementations. In some aspects, the training process of Figure 9B may represent at least a portion of a beamforming training operation that can be performed at carrier frequencies above 7 GHz (such as a directional link). In some implementations, the training process of Figure 9B may follow the training process of Figure 9A (where at least one of the AP or STA does not support antenna reciprocity). In some implementations, the AP may be an example of any one of the AP 610 or 810 of Figures 6 and 8, or the AP MLD 710 of Figure 7, respectively. In some implementations, the STA may be an example of any one of the STA 620 or 820 of Figures 6 and 8, or the non-AP MLD 720 of Figure 7, respectively.

[0077]

[0109] In the example of Figure 9B, the AP simultaneously trains its RX antennas for RX beamforming, while the STA trains its TX antennas for TX beamforming. More specifically, the training process is performed over a 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 transmits several (M) BFT packets in each of M TX beam directions (T1 - TM), and the AP attempts to receive (or listen for) the M BFT packets by tuning its RX antennas to a specific RX beam direction. More specifically, the RX antennas associated with the AP are tuned to N RX beam directions (R1 - RN) over the N training intervals 912(1) - 912(N), respectively, and remain 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 respective TX sector of the STA, and each of the RX beam directions may be associated with a respective RX sector of the AP.

[0078]

[0110] The first beam training interval 912(1) occurs between times 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 transmits 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 that can be used to train the STA's TX or RX sectors. Exemplary beam management information may include, among other examples, PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (M), sector ID, antenna ID, or the number of RX antennas or sectors associated with the STA. Due to the various pairings of the R1 and T1-TM beam directions, the AP may receive zero or more of the BFT packets transmitted by the STA between times t6 and t7. In some implementations, the AP can measure the signal power of each of the received BFT packets (if any) during the first beam training interval 912(1).

[0079]

[0111] The second beam training interval 912(2) occurs between times t7 and t8. During the second beam training interval 912(2), the STA performs a TX sector sweep while the AP is listening in the R2 beam direction. More specifically, the STA transmits 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 that can be used to train the STA's TX or RX sectors. Exemplary beam management information may include, among other examples, PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (M), sector ID, antenna ID, or the number of RX antennas or sectors associated with the STA. Due to the various pairings of the R2 and T1-TM beam directions, the AP may receive zero or more of the BFT packets transmitted by the STA between times t7 and t8. In some implementations, the AP can measure the signal power of each of the received BFT packets (if any) during the second beam training interval 912(2).

[0080]

[0112] The Nth beam training interval 912(N) is between time t9 and t 10Occurs between the STA and the AP. During the Nth beam training interval 912(N), the STA performs a TX sector sweep while the AP is listening in the RN beam direction. More specifically, the STA transmits 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 STA's TX or RX sectors. Exemplary beam management information may include, among other examples, PPDU type, training direction (TX or RX), beam tracking requirements, number of BFT packets (M), sector ID, antenna ID, or the number of RX antennas or sectors associated with the STA. Due to the various pairings of the RN and T1 - TM beam directions, the AP may receive zero or more of the M BFT packets transmitted by the STA between time t9 and t 10 and may receive zero or more of the M BFT packets transmitted by the STA between time t9 and t. In some implementations, the AP may measure the signal power of each of the BFT packets (if any) received during the Nth beam training interval 912(N).

[0081]

[0113] The AP compares the measured signal powers of the BFT packets received over the beam training intervals 912(1) to 912(N) and selects the best TX beam direction and the best RX beam direction (such as the TX and RX beam directions that result in the highest measured signal power). At time t 11 , the AP provides feedback (FB) indicating the best TX beam direction to the STA. For example, the feedback may include, among other examples, 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. Thereafter, the STA can tune its TX antenna to the best TX beam direction, and the AP can tune its RX antenna to the best RX beam direction to exchange directional communication via a directional link.

[0082]

[0114] Figure 10A shows a timing diagram 1000 illustrating an exemplary process for training an AP and a STA for TX beamforming according to some implementations. In some aspects, the training process of Figure 10A may represent at least a portion of a beamforming training operation that can be performed at carrier frequencies above 7 GHz (such as a directional link). In some implementations, the AP can be an example of any one of AP610 or 810 of Figures 6 and 8, or AP MLD710 of Figure 7. In some implementations, the STA can be an example of any one of STA620 or 820 of Figures 6 and 8, or non-AP MLD720 of Figure 7.

[0083]

[0115] The AP performs a TX sector sweep between times t0 and t1, and the STA listens in omnidirectional mode. More specifically, the AP transmits N BFT packets in N TX beam directions (T1 - TN) respectively, and the STA receives one or more of the N BFT packets without synchronizing its RX antenna for RX beamforming. Each of the T1 - TN beam directions can be associated with a respective TX sector of the AP. In some implementations, each of the N BFT packets may carry beam management information that can be used to train the TX or RX sectors of the AP. Exemplary beam management information can include, among other examples, PPDU type, training direction (TX or RX), beam tracking requirements, number of BFT packets (N), number of remaining BFT packets to be transmitted (K), sector ID, antenna ID, or the number of RX antennas or sectors associated with the AP. The STA measures the signal power of each of the BFT packets received from the AP and selects the best TX beam direction associated therewith (such as the TX beam direction that results in the highest measured signal power).

[0084]

[0116] The STA performs TX sector sweeping at times t1 and t2 while the AP is listening in omnidirectional mode. More specifically, the STA transmits several (M) BFT packets in each of M TX beam directions (T1 - TM), and the AP receives one or more of the M BFT packets without synchronizing its RX antenna for RX beamforming. Each of the T1 - TM beam directions may be associated with a respective 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 STA's TX or RX sectors. In some implementations, the beam management information may also indicate the best TX beam direction associated with the BFT packets transmitted by the AP between times t0 and t1. Exemplary beam management information may include, among other examples, PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (M), number of remaining BFT packets to be transmitted (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.

[0085]

[0117] The AP measures the signal power of each of the BFT packets received from the STA between times t1 and t2 and selects the best TX beam direction associated therewith (such as the TX beam direction that results in the highest measured signal power). At time t3, the AP provides the STA with feedback (FB) indicating the best TX beam direction associated with the BFT packets transmitted by the STA between times t1 and t2. For example, the feedback can include, among other examples, the best sector ID, the best antenna ID, or SNR reporting. Thereafter, the AP can align its TX antenna to the best TX beam direction indicated by the STA (such as via the BFT packets transmitted between times t1 and t2) to transmit a beam to the STA on the directional link. Similarly, the STA can align its TX antenna to the best TX beam direction indicated by the AP (such as via the feedback provided at time t3) to transmit a beam to the AP on the directional link.

[0086]

[0118] 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 can be terminated 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.

[0087]

[0119] Figure 10B shows timing diagram 1010, which illustrates an exemplary process for training an AP and an STA for RX beamforming according to some implementations. In some aspects, the training process of Figure 10B may represent at least a portion of a beamforming training operation that may be performed at a carrier frequency above 7 GHz (such as a directional link). In some implementations, the training process of Figure 10B may follow the training process of Figure 10A (where at least one of the AP or STA does not support antenna reciprocity). In some implementations, the AP may be an example of any one of AP 610 or 810 of Figures 6 and 8, or AP MLD 710 of Figure 7. In some implementations, the STA may be an example of any one of STA 620 or 820 of Figures 6 and 8, or non-AP MLD 720 of Figure 7.

[0088]

[0120] The AP performs an RX sector sweep between times t4 and t5, and the STA transmits several (N) training signals in the best TX beam direction (TX beam direction, TS) associated with the STA (such as the best TX beam direction indicated by the feedback at time t3 in Figure 10A). In the example of Figure 10B, each of the N training signals is transmitted as a respective BFT packet (or PPDU). More specifically, the STA transmits N BFT packets in the TS beam direction, and the AP attempts to receive the N BFT packets by tuning its RX antennas to the N RX beam directions (R1 - RN) respectively. For example, each of the R1 - RN beam directions may be associated with a respective RX sector of the AP. In some implementations, each of the N BFT packets may be able to carry beam management information (such as any of the beam management information described with reference to Figure 10A). The AP measures the signal power of each received BFT packet and selects the best RX beam direction associated therewith (such as the RX beam direction that results in the highest measured signal power).

[0089]

[0121] The STA performs RX sector sweeping between times t5 and t6, and the AP transmits several (M) training signals in the best TX beam direction (TA) associated with the AP (such as the best TX beam direction indicated by the BFT packet between times t1 and t2 in FIG. 10A). In the example of FIG. 10B, each of the M training signals is transmitted as a respective BFT packet (or PPDU). More specifically, the AP transmits M BFT packets in the TA beam direction, and the STA attempts to receive the M BFT packets by tuning its RX antenna in each of the M RX beam directions (R1 - RM). For example, each of the R1 - RM beam directions may be associated with a respective RX sector of the STA. In some implementations, each of the M BFT packets can carry beam management information (such as any of the beam management information described with reference to FIG. 10A). The STA measures the signal power of each received BFT packet and selects the best RX beam direction associated therewith (such as the RX beam direction that results in the highest measured signal power).

[0090]

[0122] After time t6, the AP can tune its RX antenna to the best RX beam direction determined as a result of its RX sector sweep (between times t4 and t5) to receive the beam transmitted by the STA on the directional link. Similarly, the STA can tune its RX antenna to the best RX beam direction determined as a result of its RX sector sweep (between times t5 and t6) to receive the beam transmitted by the AP on the directional link. In some embodiments, the training signals used to train the RX antennas of the AP and STA can be combined into a single packet or PPDU. For example, each training signal can be transmitted as a respective training field (TRN) of the same PPDU. In some implementations, such a PPDU can also carry data directed to the AP or STA. The process of using the TRN to train the TX or RX antennas of a wireless communication device for beamforming is referred to herein as "beam fine-tuning."

[0091]

[0123] FIG. 10C shows another timing diagram 1020 illustrating an exemplary process for training an AP and STA for RX beamforming according to some embodiments. In some aspects, the training process of FIG. 10C can represent at least a portion of a beamforming training operation that can be performed on a carrier frequency above 7 GHz (such as a directional link). In some implementations, the training process of FIG. 10C can follow the training process of FIG. 10A (where at least one of the AP or STA does not support antenna reciprocity). In some implementations, the AP can be an example of any of the AP610 or 810 of FIGS. 6 and 8, or the AP MLD710 of FIG. 7, respectively. In some implementations, the STA can be an example of any of the STA620 or 820 of FIGS. 6 and 8, or the non-AP MLD720 of FIG. 7, respectively.

[0092]

[0124] The AP performs RX beam fine-tuning between times t4 and t5, and the STA transmits a series of training signals in the best TX beam direction (TS) associated with the STA (such as the best TX beam direction indicated by the feedback at time t3 in FIG. 10A). In the example of FIG. 10C, each of the training signals is transmitted as a respective 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 can transmit several (N) TRNs in the TS beam direction, and the AP attempts to receive the N TRNs by tuning its RX antennas to N RX beam directions (R1-RN) respectively, where each of the R1-RN beam directions is associated with a respective RX sector of the AP (as shown in FIG. 10C). In some other implementations, the STA can transmit several (K) TRNs in the TS beam direction, and the AP attempts to receive each of the K TRNs via each antenna element (listening in an omnidirectional mode). In some aspects, the PPDU can carry beam management information associated with the N TRNs (such as any of the beam management information described with reference to FIG. 10A). In some implementations, the AP can measure the signal power of each received TRN and select the best RX beam direction associated therewith (such as the RX beam direction associated with the RX sector or antenna element that results in the highest measured signal power).

[0093]

[0125] The STA performs RX beam fine-tuning between times t5 and t6, and the AP transmits a series of training signals in the best TX beam direction (TA) associated with the AP (such as the best TX beam direction indicated by the BFT packet between times t1 and t2 in FIG. 10A). In the example of FIG. 10C, each of the training signals is transmitted as a respective TRN of the PPDU. In other words, the series of training signals share the same PHY preamble. In some implementations, the AP can transmit several (M) TRNs in the TA beam direction, and the STA attempts to receive the M TRNs by tuning its RX antennas in M RX beam directions (R1 - RM) respectively, where each of the R1 - RM beam directions is associated with a respective RX sector of the STA (as shown in FIG. 10C). In some other implementations, the AP can transmit several (L) TRNs in the TA beam direction, and the STA attempts to receive each of the L TRNs via each antenna element (listen in an omnidirectional mode). In some aspects, the PPDU can carry beam management information associated with the M TRNs (such as any of the beam management information described with reference to FIG. 10A). In some implementations, the STA can measure the signal power of each received TRN and select the best RX beam direction associated therewith (such as the RX beam direction associated with the RX sector or antenna element that results in the highest measured signal power).

[0094]

[0126] After time t6, the AP can tune its RX antenna to the best RX beam direction determined as a result of its RX beam fine-tuning (between times t4 and t5) to receive the beam transmitted by the STA on the directional link. Similarly, the STA can tune its RX antenna to the best RX beam direction determined as a result of its RX beam fine-tuning (between times t5 and t6) to receive the beam transmitted by the AP on the directional link. In some implementations, the beam fine-tuning protocol can be used with data communication. In such implementations, the TRN can be appended to the end of the PPDU that includes the data portion. For example, referring to FIG. 10C, the PPDU transmitted by the STA (between times t4 and t5) can include a data portion (between the PHY preamble and the TRN) that carries data addressed to the AP. Similarly, the PPDU transmitted by the AP (between times t5 and t6) can include a data portion (between the PHY preamble and the TRN) that carries data directed to the STA.

[0095]

[0127] Aspects of the present disclosure recognize that an AP and an STA may need to perform multiple beamforming training operations over time to maintain communication via a wireless communication link. For example, the AP and the STA may need to re-train their TX and RX antennas when a directional link is broken or when the STA re-associates with the AP. Further, the best TX or RX beam direction may change due to movement of the STA (or AP) or a change in the channel state (or other environmental factors). In some aspects, the AP and the STA may periodically perform subsequent beamforming training operations to re-train their TX or RX antennas. In some other aspects, the AP and the STA may perform subsequent beamforming training operations when a link quality metric falls below a threshold level. In some implementations, each subsequent beamforming training operation may include a full scan of all TX and RX beam directions associated with the AP and the STA. In some other implementations, each subsequent beamforming training operation (after the first beamforming training operation) may include only a partial scan of the TX and RX beam directions associated with the AP and the STA (such as a subset of TX or RX beam directions centered around the best TX or RX beam direction from the previous scan).

[0096]

[0128] In some implementations, the AP and STA may retrain their TX antennas by performing TX sector sweeping (as described with reference to any of FIGS. 9A, 9B, and 10A). In some implementations, the AP and STA can retrain their RX antennas by performing RX sector sweeping (as described with reference to any of FIGS. 9A, 9B, and 10B). In some other implementations, the AP and STA can retrain their RX antennas using a beam fine-tuning protocol (as described with reference to FIG. 10C). Still further, in some implementations, the AP and STA may use a beam fine-tuning protocol to retrain their TX antennas.

[0097]

[0129] FIG. 11 shows another timing diagram 1100 illustrating an exemplary process for training an AP and STA for TX beamforming according to some implementations. In some aspects, the training process of FIG. 11 may represent at least a portion of a beamforming training operation that can be performed at carrier frequencies above 7 GHz (such as a directional link). In some implementations, the AP can be an example of any of AP610 or 810 of FIGS. 6 and 8, or AP MLD710 of FIG. 7, respectively. In some implementations, the STA can be an example of any of STA620 or 820 of FIGS. 6 and 8, or non-AP MLD720 of FIG. 7, respectively.

[0098]

[0130] During the time between t0 and t1, the AP performs TX beam fine-tuning by transmitting a PPDU containing several (N) TRNs while the STA is listening in the best RX beam direction (RX beam direction, RS) associated with the STA (such as the best RX beam direction determined as a result of the STA RX sector sweep in Figure 10B or the STA RX beam fine-tuning in Figure 10C). More specifically, the AP transmits N TRNs in 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 to TN beam directions can be associated with a respective TX sector of the AP. In some implementations, the PPDU can carry beam management information associated with the N TRNs (such as any of the beam management information described with reference to Figure 10A). The STA measures the signal power of each received TRN and selects the best TX beam direction associated therewith (such as the TX beam direction that results in the highest measured signal power). At time t2, the STA provides feedback indicating the best TX beam direction (such as the best sector ID or the best element ID) to the AP.

[0099]

[0131] During the period between time t3 and t4, the STA performs TX beam fine-tuning by transmitting a PPDU containing several (M) TRNs while listening in the best RX beam direction (RA) associated with the AP (such as the best RX beam direction determined as a result of the AP RX sector sweep in FIG. 10B or the AP RX beam fine-tuning in FIG. 10C). More specifically, the STA transmits M TRNs in 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 to TM beam directions may be associated with a respective TX sector of the STA. In some implementations, the PPDU can carry beam management information associated with the M TRNs (such as any of the beam management information described with reference to FIG. 10A). The AP measures the signal power of each received TRN and selects the best TX beam direction associated therewith (such as the TX beam direction that results in the highest measured signal power). At time t5, the AP provides feedback indicating the best TX beam direction (such as the best sector ID or the best element ID) to the STA.

[0100]

[0132] After time t5, the AP can align its TX antenna to the best TX beam direction determined as a result of its TX beam fine-tuning (between times t0 and t1) to transmit a beam to the STA on the directional link. Similarly, the STA can align its TX antenna to the best TX beam direction determined as a result of its TX beam fine-tuning (between times t3 and t4) to transmit a beam to the AP on the directional link. In some implementations, the beam fine-tuning protocol can be used with data communication. In such implementations, the TRN can be added to the end of the PPDU containing the data portion. For example, referring to FIG. 11, the PPDU transmitted by the AP (between times t0 and t1) can include a data portion (between the PHY preamble and the TRN) that carries data addressed to the STA. Similarly, the PPDU transmitted by the STA (between times t3 and t4) can include a data portion (between the PHY preamble and the TRN) that carries data addressed to the AP.

[0101]

[0133] Aspects of the present disclosure recognize that beamforming gain is significantly greater when TX beamforming is used in a transmitting device in combination with RX beamforming in a receiving device (such as when performing any of the training processes described with reference to FIGS. 9A, 9B, 10B, 10C, and 11) than when TX beamforming is used in a transmitting device and the receiving device operates in an omnidirectional mode (such as when performing the training process described with reference to FIG. 10A). In some aspects, a “data PHY” (DPHY) PPDU format may be used when transmitting a beam to a receiving device configured for RX beamforming, and a “control PHY” (CPHY) PPDU format may be used when transmitting a beam to a receiving device operating in an omni-directional mode. More specifically, the CPHY PPDU format may be designed to overcome the one-sided beamforming gain on a directional link more than the DPHY PPDU format. In some implementations, the CPHY PPDU format and the DPHY PPDU format may conform to existing PPDU formats associated with the sub-7 GHz frequency band.

[0102]

[0134] As described above, wireless communication at higher carrier frequencies can be plagued by greater phase noise compared to wireless communication at lower frequency bands. For example, increasing the carrier frequency from 5.8 GHz to 60 GHz results in a ten-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 with reference to FIG. 2A, existing WLAN packet formats include an L-STF that is modulated every fourth subcarrier across a given bandwidth to support carrier frequency offset (CFO) estimation up to two subcarriers apart. Further, local oscillators (LOs) implemented by existing WLAN transmitters and receivers are required to be accurate up to ±20 ppm. Thus, existing WLAN architectures can support a CFO of up to ±40 ppm (between the transmitter and receiver), which corresponds to ±2.4 MHz in the 60 GHz frequency band and ±1.8 MHz in the 45 GHz frequency band. To support a CFO of up to ±2.4 MHz, the SCS associated with the L-STF should be 1.2 MHz or greater.

[0103]

[0135] In some aspects, a wireless communication device (such as an AP or STA) may upclock a PPDU for transmission at a carrier frequency above 7 GHz, and the PPDU conforms to an existing PPDU format associated with the sub-7 GHz frequency band. As used herein, the term "upclock" refers to increasing the frequency of a clock signal used to convert a PPDU between the frequency domain and the time domain (beyond the frequency (f0) associated with the existing PPDU format), and the ratio (R) of the upclocked frequency (f s ) to f0 is herein referred to as the "upclock ratio"

[0104]

Number

[0105] is called. 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 converts several (n) modulated subcarriers representing a PPDU into n time-domain samples. In some aspects, the ratio of the clock signal frequency f IFFT to the IFFT size (n s ) can result in an SCS of 1.2 MHz or more, 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 upclocking (SCS U ) can be a multiple of the SCS associated with an existing PPDU format (SCS0), and SCS U = R * SCS0.

[0106]

[0136] FIG. 12 shows a block diagram of an exemplary 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 on a directional link. In some aspects, the PPDU 1201 can be an example of the PPDU 300 of FIG. 3. In some implementations, the wireless communication device can be an example of any of the AP610 or 810 of FIGS. 6 and 8, or the AP MLD710 of FIG. 7, respectively. In some other implementations, the wireless communication device can be an example of any of the STA620 or 820 of FIGS. 6 and 8, or the non-AP MLD720 of FIG. 7, respectively. Thus, the directional link can be an example of any of the directional links 704 or 804 of FIGS. 7 and 8, respectively. For simplicity, only a single spatial stream of the TX processing chain 1200 is shown in FIG. 12. In an actual implementation, the TX processing chain 1200 can include any number of spatial streams.

[0107]

[0137] The TX processing chain 1200 includes a constellation mapper 1210, an orthogonal frequency division multiplexing (OFDM) modulator 1220, an RF mixer 1230, and a power amplifier (PA) 1240. The constellation mapper 1210 maps the PPDU 1201 to one or more frequency-domain (FD) symbols 1202 associated with the modulation scheme. Exemplary 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 symbol 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 the 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 the LO signal 1204 oscillating at the carrier frequency. In the example of FIG. 12, the carrier frequency associated with the LO signal 1204 is shown as being higher than 7 GHz. In some implementations, the carrier frequency may be in the 60 GHz frequency band. In some other implementations, the carrier frequency may be in the 45 GHz frequency band.

[0108]

[0138] As described above, many existing WLAN architectures are designed for wireless communication on carrier frequencies below 7 GHz (such as the 2.4 GHz, 5 GHz, or 6 GHz frequency bands). In some aspects, existing WLAN hardware can be reused to support wireless communication on carrier frequencies above 7 GHz. For example, TX processing chain 1200 may receive LO signal 1204 from a local oscillator that is accurate up to ±20 ppm. As described above, increasing the carrier frequency of LO signal 1204 also increases the phase noise associated with RF signal 1205. For example, operating the local oscillator at 60 GHz can result in a CFO of ±2.4 MHz between the transmitter and the receiver. According to existing versions of the IEEE 802.11 standard, the PHY preamble of PPDU 1201 includes an L-STF with a symbol duration of 1x associated with an SCS equal to 312.5 KHz that can support CFO estimation up to 2 subcarriers apart. 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 a CFO up to ±2.4 MHz, the 1x SCS associated with PPDU 1201 should be 1.2 MHz or more.

[0109]

[0139] Aspects of the present disclosure recognize that any SCS greater than or equal to 1.2 MHz may not be suitable for wireless communication on sub-7 GHz carrier frequencies. Thus, existing WLAN communication protocols for sub-7 GHz wireless communication (such as IEEE 802.11be, 11ax, 11ac, and earlier revisions of the IEEE 802.11 standard) do not define PPDU formats or tone plans with SCSs of 1.2 MHz or greater. In some aspects, the TX processing chain 1200 may receive a PPDU 1201 formatted for transmission on a sub-7 GHz carrier frequency and may up-convert the PPDU 1201 to a wider bandwidth suitable for transmission on a carrier frequency above 7 GHz (such as in the 60 GHz or 45 GHz frequency bands). For example, the wider bandwidth is achieved by spreading the subcarriers to which the PPDU 1201 is mapped. In some implementations, the TX processing chain 1200 may up-convert the PPDU 1201 such that the 1x SCS associated with the PPDU 1201 is 1.2 MHz or greater.

[0110]

[0140] In some implementations, PPDU 1201 may conform to the PPDU format defined by the IEEE 802.11ac amendment of the IEEE 802.11 standard (also referred to as the "11ac PPDU format"). For example, PPDU 1201 may conform to the 11ac PPDU format associated with a 20 MHz, 40 MHz, 80 MHz, 80+80 MHz, or 160 MHz channel bandwidth (in the sub-7 GHz frequency band), and may be upclocked 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 the 60 GHz or 45 GHz frequency band. In some other implementations, PPDU 1201 may conform to the PPDU format defined by the IEEE 802.11be (or 11ax) amendment of the IEEE 802.11 standard (also referred to as the "11be PPDU format"). For example, PPDU 1201 may conform to the 11be PPDU format associated with a 20 MHz, 40 MHz, or 80 MHz channel bandwidth (in the sub-7 GHz frequency band), and may be upclocked 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 the 60 GHz or 45 GHz frequency band.

[0111]

[0141] FIG. 13A shows an exemplary PPDU 1300 formatted according to the legacy PPDU format. In the example of FIG. 13A, the legacy PPDU format is the 11ac PPDU format associated with an 80 MHz channel bandwidth. The PPDU 1300 includes a PHY preamble, has 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, and a first non-legacy signal field (SIG-A) spanning a first symbol (first symbol, SIG-A1) and a second symbol (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).

[0112]

[0142] The IEEE 802.11ac amendment to the IEEE802.11 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, PPDU 1300 can be upclocked as a DPHY PPDU for wireless communication on carrier frequencies above 7 GHz. In such implementations, one or more of the signal fields in the first portion 1301 can be reused to carry beam management information 1305. Exemplary beam management information 1305 can include, among other examples, the PPDU type (indicating whether PPDU 1300 is a normal PPDU or part of a sector sweep or beam fine-tuning training process), the training direction (such as TX or RX), the beam tracking requirement (signaling the presence of a TRN at the end of the PPDU), the training length (indicating the total number of BFT packets or TRNs to be transmitted), the best antenna ID, the best sector ID, the number of RX antennas of the transmitting device, or SNR reports. As shown in FIG. 13A, the first preamble portion 1301 is replicated over four 20 MHz sub-bands spanning an 80 MHz bandwidth. According to the 11ac PPDU format, the first preamble portion 1301, the second preamble portion 1302, and the data portion 1303 are mapped to the same subcarriers.

[0113]

[0143] FIG. 13B shows an exemplary upclocked PPDU 1310 based on the PPDU format shown in FIG. 13A according to some implementations. PPDU 1310 includes a PHY preamble 1311 followed by a packet extension (PE) or one or more TRNs 1314. In some aspects, PPDU 1310 can represent an upclocking of PPDU 1300 by a factor of M. In such aspects, the PHY preamble 1311 can be an example of the first preamble portion 1301 of FIG. 13A.

[0114]

[0144] In some implementations, PPDU 1310 can be a DPHY PPDU that can be used for various beamforming training procedures (such as any of the BFT packets in FIGS. 9A, 9B, and 10B, or any of the PPDUs in FIG. 10C). In such implementations, beam management information can be carried in one or more of the signal fields L-SIG, SIG-A1, or SIG-A2. For example, referring to FIG. 13A, the data portion 1303 and its associated PHY preamble field (such as the second preamble portion 1302) can be omitted from PPDU 1310 to reduce overhead. In some aspects, the upclocking can be performed by the OFDM modulator 1220 of FIG. 12. For example, the OFDM modulator 1220 can upclock PPDU 1300 by a factor of M to generate an upclocked PPDU 1310. As a result, PE or TRN 1314 is spread over an 80 * M MHz bandwidth, and the PHY preamble 1311 is replicated over four 20 * M MHz subbands over an 80 * M MHz bandwidth.

[0115]

[0145] FIG. 13C shows another exemplary upclocked PPDU 1320 based on the PPDU format shown in FIG. 13A according to some implementations. PPDU 1320 includes a PHY preamble 1321, a data portion 1323, and PE or one or more TRNs 1324. In some aspects, PPDU 1320 can represent an upclocking of PPDU 1300 by a factor of M. In such aspects, the PHY preamble 1321 and the data portion 1323 can be examples of the first preamble portion 1301 and the data portion 1303 of FIG. 13A, respectively.

[0116]

[0146] In some implementations, PPDU 1320 can be a DPHY PPDU that can be used for beam fine-tuning (such as the PPDU of FIGS. 10C and 11). In such an implementation, beam management information can be carried in one or more of the signal fields L-SIG, SIG-A1, or SIG-A2, and data portion 1323 can carry data directed to a receiving device (such as an AP or STA). In some implementations, the second preamble portion 1302 of FIG. 13A can be omitted from PPDU 1320. In some other implementations, PPDU 1320 can further include one or more non-legacy LTFs 1322 to support data transmission via, for example, multiple spatial streams (N SS >1). In some aspects, upsampling can be performed by OFDM modulator 1220 of FIG. 12. For example, OFDM modulator 1220 can upsample PPDU 1300 by M times to generate an upsampled PPDU 1320. As a result, LTF 1322 (if any), data portion 1323, and PE or TRN 1324 are spread over an 80 * M MHz bandwidth, and PHY preamble 1321 (excluding LTF 1322) is replicated over four 20 * M MHz subbands spanning an 80 * M MHz bandwidth.

[0117]

[0147] FIG. 14A shows an exemplary PPDU 1400 formatted according to the legacy PPDU format. In the example of FIG. 14A, 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 part 1401 and a second part 1402, followed by a data part 1403 and a PE 1404. The first preamble part 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 part 1402 includes a non-legacy short training field (STF) and one or more non-legacy long training fields (LTFs).

[0118]

[0148] IEEE 802.11, which is a revised version of the IEEE 802.11 standard, defines the first non-legacy signal field SIG1 as the Universal Signal Field (U-SIG), and the remaining non-legacy fields SIG2, STF, and LTF as the Extremely High Throughput (EHT) fields EHT-SIG, EHT-STF, and EHT-LTF, respectively. In some implementations, PPDU 1400 can be upclocked 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 1401 can be reused to carry beam management information 1405. Exemplary beam management information 1305 can include, among other examples, 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. According to the 11be PPDU format, the data portion 1403 (and PE 1404) is mapped to each consecutive data subcarrier associated with a 256-subcarrier tone plan (including 234 data subcarriers and 8 pilot subcarriers). In contrast, L-STF is mapped to every fourth data subcarrier associated with a 64-subcarrier tone plan, and the remainder of the first preamble portion 1401 is mapped to each consecutive data subcarrier associated with a 64-subcarrier tone plan. Therefore, the SCS associated with L-STF is four times larger than the SCS associated with the data portion 1403.

[0119]

[0149] Figure 14B shows an exemplary up - clocked PPDU based on the PPDU format shown in Figure 14A according to some implementations. PPDU 1410 includes a PHY preamble 1411 followed by a PE or one or more TRNs 1414. In some embodiments, PPDU 1410 may represent the up - clock of PPDU 1400 of M. In such an embodiment, the PHY preamble 1411 and the PE or TRN 1414 may be examples of the first preamble portion 1401 and PE 1404 of Figure 14A, respectively.

[0120]

[0150] In some implementations, PPDU 1410 may be a DPHY PPDU that can be used for various beamforming training procedures (such as any of the BFT packets in Figures 9A, 9B, and 10B, or any of the PPDUs in Figure 10C). In such an implementation, the signal fields L - SIG, RL - SIG, SIG1, and SIG2 of Figure 14A can be condensed or aggregated as a single DPHY signal field (signal, SIG) in the PHY preamble 1411 for carrying beam management information. For example, referring to Figure 14A, the data portion 1403 and its associated PHY preamble fields (such as the second preamble portion 1402) can be omitted from PPDU 1410 to reduce overhead. In some embodiments, the up - clock can be performed by the OFDM modulator 1220 of Figure 12. For example, the OFDM modulator 1220 can up - clock PPDU 1400 by M times to generate the up - clocked PPDU 1410. As described with reference to Figure 14A, 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 can span a significantly shorter duration than the PHY preamble 1311 of Figure 13B (assuming the same PPDU bandwidth).

[0121]

[0151] Figure 14C shows another exemplary up - clocked PPDU 1420 based on the PPDU format shown in Figure 14A according to some implementations. PPDU 1420 includes a PHY preamble 1421, a data portion 1423, and a PE or one or more TRNs 1424. In some aspects, PPDU 1420 may represent an up - clocked PPDU 1400 by a factor of M. In such aspects, the PHY preamble 1421, the data portion 1423, and the PE or TRN 1414 may be examples of the first preamble portion 1401, the data portion 1403, and the PE 1404 of Figure 14A, respectively.

[0122]

[0152] In some implementations, PPDU 1410 may be a DPHY PPDU that can be used for beam fine - tuning (such as any of the PPDUs of Figures 10C and 11). In such implementations, the signal fields L - SIG, RL - SIG, SIG1, and SIG2 of Figure 14A may be condensed or aggregated as a single DPHY signal field (SIG) in the PHY preamble 1421 for carrying beam management information, and the data portion 1423 may carry data targeted at a receiving device (such as an AP or STA). In some implementations, the second preamble portion 1402 of Figure 14A may be omitted from PPDU 1420. In some other implementations, PPDU 1420 may further include one or more non - legacy LTFs 1422 to support data transmission via, for example, multiple spatial streams (N SS > 1). In some aspects, the up - clocking may be performed by the OFDM modulator 1220 of Figure 12. For example, the OFDM modulator 1220 may up - clock the PPDU 1400 by a factor of M to generate the up - clocked PPDU 1420. As described with reference to Figure 14B, the PHY preamble 1421 may have a significantly shorter duration than the PHY preamble 1321 of Figure 13C (assuming the same PPDU bandwidth).

[0123]

[0153] FIG. 15A shows an exemplary PPDU 1500 formatted according to the legacy PPDU format. In the example of FIG. 15A, the legacy PPDU format is the 11be PPDU format associated with a 20 MHz channel bandwidth. More specifically, the PPDU 1500 conforms to the extended range (ER) single user (SU) PPDU format. The 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 L-SIG (RL-SIG), and four non-legacy signal fields (SIG1 to SIG4). The second preamble part 1502 includes a non-legacy short training field (STF) and one or more non-legacy long training fields (LTFs).

[0124]

[0154] IEEE 802.11, which is a revised version of the IEEE 802.11 standard, defines each of the non-legacy signal fields SIG1 to SIG4 as U-SIG, and the remaining non-legacy fields STF and LTF as the EHT fields EHT-STF and EHT-LTF, respectively. Further, the STF sequence associated with L-STF is repeated (2x) in the time domain to generate an "extended L-STF". In some implementations, PPDU1500 can be upclocked as a CPHY PPDU for wireless communication on carrier frequencies above 7 GHz. In such implementations, one or more of the signal fields in the first portion 1501 can be reused to carry beam management information 1505. Exemplary beam management information 1505 can include, among other examples, PPDU type, training direction, beam tracking request, training length, countdown (indicating the number of remaining training signals to be transmitted), sector ID, antenna ID, best antenna ID, best sector ID, number of RX sectors or RX antennas of the transmitting device, or SNR report. According to the 11be PPDU format, the data portion 1503 (and PE1504) is mapped to each consecutive data subcarrier associated with a 256 subcarrier tone plan. In contrast, L-STF is mapped to every fourth data subcarrier associated with a 64 subcarrier tone plan, and the remainder of the first preamble portion 1501 is mapped to each consecutive data subcarrier associated with a 64 subcarrier tone plan. Thus, the SCS associated with L-STF is four times larger than the SCS associated with the data portion 1503.

[0125]

[0155] Figure 15B shows an exemplary up - clocked PPDU 1510 based on the PPDU format shown in Figure 15A according to some implementations. PPDU 1510 includes a PHY preamble 1511 followed by a PE or one or more TRNs 1514. In some aspects, PPDU 1510 may represent an up - clocking of the M - fold PPDU 1500. In such aspects, the PHY preamble 1511 and the PE or TRN 1514 may be examples of the first preamble portion 1501 and the PE 1504 in Figure 15A, respectively.

[0126]

[0156] In some implementations, PPDU 1510 may be a CPHY PPDU that can be used for various beamforming training procedures (such as either the BFT packet in Figure 10A or BRP - Rx using single - element measurements). In such implementations, beam management information may be carried in one or more of the signal fields L - SIG, RL - SIG, or SIG1 - SIG4. For example, referring to Figure 15A, the data portion 1503 and its associated PHY preamble field (such as the second preamble portion 1502) may be omitted from PPDU 1510 to reduce overhead. As described with reference to Figure 15A, the SCS associated with the L - STF is four times larger than the SCS associated with the PE 1504. Thus, the first preamble portion 1501 may be up - clocked by a factor of M / 4 to achieve the same SCS in the L - STF as in the PE 1504 and may be replicated four times in the frequency domain. In some aspects, the up - clocking may be performed by the OFDM modulator 1220 in Figure 12. In some implementations, the OFDM modulator 1220 may up - clock the first preamble portion 1501 by a factor of M / 4 and up - clock the rest of the PPDU 1500 by a factor of M to generate the PPDU 1510. As a result, the PE or TRN 1514 is spread over a 20 * M MHz bandwidth, and the PHY preamble 1511 is 20 * M MHz bandwidth over four 5 *It is replicated on the M MHz sub-band.

[0127]

[0157] As described with reference to FIGS. 13A - 15B, the overhead associated with beamforming training can be reduced by reusing various fields of the PHY preamble to carry beam management information (thus omitting the data part of the PPDU). Aspects of the present disclosure recognize that the overhead associated with beamforming training can be further reduced by offloading at least a portion of the signaling overhead associated with the beamforming training operation onto the anchor link.

[0128]

[0158] FIG. 16 shows a timing diagram 1600 illustrating an exemplary 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 can be an example of any of AP610 or 810 of FIGS. 6 and 8, or AP MLD710 of FIG. 7. In some implementations, the STA can be an example of any of STA620 or 820 of FIGS. 6 and 8, or non - AP MLD720 of FIG. 7. For example, referring to FIGS. 7 and 8, the anchor link can be an example of either anchor link 702 or 802, and the directional link can be an example of either directional link 704 or 804.

[0129]

[0159] At time t0, the AP (as a beamforming initiator) transmits, on the anchor link, a trigger frame signaling 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. Thus, the STA can operate in a power-saving mode on the directional link until it receives the trigger frame from the AP.

[0130]

[0160] In some implementations, the beam management setup information can include a subset of the beam management information (such as any of the beam management information 1305, 1405, or 1505 of FIGS. 13A, 14A, and 15A, respectively) that would otherwise be included in the BFT packets transmitted during the beamforming training operation. More specifically, the beam management setup information may include any information common to each of the BFT packets. Exemplary beam management setup information can include, among other examples, the total number of BFT packets (N) to be transmitted by the AP, the number of TX and RX antennas or sectors associated with the AP, or the total number of BFT packets (K) permitted to be transmitted by the STA.

[0131]

[0161] At time t1, the AP starts a beamforming training operation by transmitting N BFT packets in various TX beam directions on a directional link (as described with reference to FIGS. 9A or 10A). More specifically, at least one BFT packet may be transmitted by each TX sector (such as TX sectors T1 to T7 in FIG. 6) associated with the AP. In some implementations, each of the BFT packets may carry beam management information that can be used to train the TX or RX sectors of the AP. More specifically, the beam management information may include any information that has not yet been signaled via a trigger frame. Exemplary beam management information may include, among other examples, PPDU type, training direction (TX or RX), beam tracking request, number of remaining BFT packets to be transmitted (L), sector ID, or antenna ID. Thus, transmitting a trigger frame on an anchor link further reduces the overhead associated with each of the BFT packets.

[0132]

[0162] 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 BFT packet has the highest received signal power. For example, the feedback may include, among other examples, the best sector ID, the best antenna ID, or an SNR report. In some implementations, the STA can further train its RX antenna for RX beamforming (as described with reference to FIG. 9A) based on the BFT packets transmitted by the AP between times t1 and t2. In some other implementations, the STA can perform additional packet exchanges with the AP between times t2 and t3 to train its RX antenna (as described while referring to FIGS. 10B or 10C). In some aspects, the AP can train its RX antenna for RX beamforming based on additional packet exchanges (such as those described while referring to FIGS. 9B, 10B, or 10C). In some other aspects, the STA can train its TX antenna for TX beamforming based on additional packet exchanges (such as those described while referring to FIGS. 9B or 10A).

[0133]

[0163] As described with reference to FIG. 16, a trigger frame transmitted on an anchor link (at time t0) may provide a timing reference for communication on a directional link. In some implementations, the trigger frame may further provide a frequency reference for communication on the directional link. In such implementations, the same local oscillator of the AP may drive the carrier frequencies used by the AP for wireless communication on each of the anchor link and the directional link, and the same local oscillator of the STA may drive the carrier frequencies used by the STA for wireless communication on each of the anchor link and the directional link. As a result, the STA can estimate the CFO on the anchor link based on the trigger frame received at time t0, and use the CFO estimate associated with the anchor link to narrow the range of possible CFO estimates for the directional link (such as within a few kilohertz). Thus, the anchor link and the directional link are "synchronized in frequency".

[0134]

[0164] In some implementations, the AP may include a clock that controls the timing of wireless communication by the AP on the directional link and the anchor link, and the STA may include a clock that controls the timing of wireless communication by the STA on the directional link and the anchor link. For example, the same clock can control the time when the trigger frame is transmitted on the anchor link and the time when the BFT packet is transmitted on the directional link. Thus, 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, the receiving device can determine the timing and CFO associated with the BFT packet transmitted on the directional link based on the timing and CFO associated with the trigger frame transmitted on the anchor link. As a result, the BFT packet can carry significantly less overhead than a BFT packet transmitted on the anchor link without timing and frequency references.

[0135]

[0165] Figure 17A shows a timing diagram 1700 illustrating an exemplary 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 can be an example of any of the AP610 or 810 of FIGS. 6 and 8, or the AP MLD710 of FIG. 7, respectively. In some implementations, the STA can be an example of any of the STA620 or 820 of FIGS. 6 and 8, or the non-AP MLD720 of FIG. 7, respectively. For example, referring to FIGS. 7 and 8, the anchor link can be an example of either the anchor link 702 or 802, and the directional link can be an example of either the directional link 704 or 804.

[0136]

[0166] In the example of FIG. 17A, the directional link and the anchor link are synchronized in both time and frequency. In other words, the same local oscillator drives the carrier frequencies used for wireless communication by the AP in each of the anchor link and the directional link, and the same clock controls the timing of the wireless communication by the AP in each of the anchor link and the directional link. Similarly, the same local oscillator drives the carrier frequencies used for wireless communication by the STA in each of the anchor link and the directional link, and the same clock controls the timing of the wireless communication by the STA in each of the anchor link and the directional link.

[0137]

[0167] At time t0, the AP (as a beamforming initiator) transmits on the anchor link a trigger frame signaling the start of a beamforming training operation to be performed on the directional link. In the example of FIG. 17A, the beamforming training operation is scheduled to occur from time t1 to t3. In some implementations, the trigger frame may carry beam management setup information indicating one or more parameters associated with the beamforming training operation. For example, the beam management setup information may include a subset of the beam management information (such as any of the beam management information 1305, 1405, or 1505 of FIGS. 13A, 14A, and 15A, respectively) that would otherwise be included in the BFT packets transmitted during the beamforming training operation. More specifically, the beam management setup information may include any information common to each of the BFT packets. Exemplary beam management setup information may include, among other examples, the total number (N) of BFT packets to be transmitted by the AP, the number of TX and RX antennas or sectors associated with the AP, or the total number (K) of BFT packets permitted to be transmitted by the STA.

[0138]

[0168] In some aspects, the trigger frame may further provide timing and frequency references for wireless communication on the directional link. For example, the beam management setup information may include timing and frequency information indicating the timing of wireless communication on the directional link and the CFO associated therewith. In other words, the STA knows that the beamforming training operation is to be performed on the directional link at time t1 based on the timing information included in or derived from receiving the trigger frame. Further, the STA can estimate the CFO associated with the wireless communication on the directional link based on the frequency information included in the trigger frame (such as the L-STF). Thus, the L-STF can be omitted from each BFT packet transmitted on the directional link by the beam management setup information carried in the trigger frame. In the example of FIG. 17A, each of the BFT packets is shown as a short training sequence (TS).

[0139]

[0169] At time t1, the AP starts a beamforming training operation by transmitting N training sequences in various TX beam directions on a directional link (as described with reference to FIGS. 9A or 10A). More specifically, at least one training sequence can be transmitted by each TX sector (such as TX sectors T1 to T7 in FIG. 6) associated with the AP. In some aspects, the STA can determine the sector ID of the (AP) sector from which the training sequence is transmitted based on the trigger frame received on the anchor link (at time t0) and the timing of each training sequence (as indicated by the timestamp). In some other aspects, each of the training sequences can carry beam management information that explicitly signals one or more training parameters. More specifically, the beam management information can include any information that has not yet been signaled via the trigger frame. In some implementations, each of the training sequences can consist 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 implementations, each of the training sequences can consist of an LTF and a signal field (such as a non-legacy SIG) to carry additional beam management information (such as a training direction, a beam tracking request, a sector ID, the number of remaining training sequences (L) to be transmitted, or an antenna ID, etc.).

[0140]

[0170] The STA receives one or more of the training sequences and compares the signal power 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 can include, among other examples, the best sector ID, the best antenna ID, or an SNR report. In some implementations, the STA can further train its RX antenna for RX beamforming based on the training sequences transmitted by the AP between times t1 and t2 (as described with reference to FIG. 9A). In some other implementations, the STA can perform additional packet exchanges with the AP between times t2 and t3 to train its RX antenna (as described with reference to FIGS. 10B or 10C). In some aspects, the AP can train its RX antenna for RX beamforming based on additional packet exchanges (as described with reference to FIGS. 9B, 10B, or 10C). In some other aspects, the STA can train its TX antenna for TX beamforming based on additional packet exchanges (as described with reference to FIGS. 9B or 10A).

[0141]

[0171] FIG. 17B shows another timing diagram 1710 illustrating an exemplary beamforming training operation between an AP and an STA via an anchor link (AL) and a directional link (DL) according to some implementations. In some implementations, the AP can be an example of any of the AP610 or 810 of FIGS. 6 and 8, or the AP MLD710 of FIG. 7, respectively. In some implementations, the STA can be an example of any of the STA620 or 820 of FIGS. 6 and 8, or the non-AP MLD720 of FIG. 7, respectively. Referring to FIGS. 7 and 8 for example, the anchor link can be an example of either anchor link 702 or 802, and the directional link can be an example of either directional link 704 or 804.

[0142]

[0172] In the example of FIG. 17B, 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 for wireless communication by the AP in each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the AP in each of the anchor link and the directional link. Similarly, the same local oscillator drives the carrier frequency used for wireless communication by the STA in each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the STA in each of the anchor link and the directional link.

[0143]

[0173] At time t0, the AP (as a beamforming initiator) transmits a trigger frame on the anchor link that signals the start of a beamforming training operation to be performed on the directional link. In the example of FIG. 17B, the beamforming training operation is scheduled to occur from time t1 to t3. In some implementations, the trigger frame may carry beam management setup information indicating one or more parameters associated with the beamforming training operation. For example, the beam management setup information may include a subset of the beam management information (such as any of the beam management information 1305, 1405, or 1505 of FIGS. 13A, 14A, and 15A, respectively) that would otherwise be included in the BFT packets transmitted during the beamforming training operation. More specifically, the beam management setup information may include any information common to each of the BFT packets. Exemplary beam management setup information may include, among other examples, the total number (N) of BFT packets to be transmitted by the AP, the number of TX and RX antennas or sectors associated with the AP, or the total number (K) of BFT packets permitted to be transmitted by the STA.

[0144]

[0174] In some aspects, the trigger frame may further provide timing and frequency references for wireless communication on the directional link. For example, the beam management setup information may include timing and frequency information indicating the timing of wireless communication on the directional link and the CFO associated therewith. In other words, the STA knows that the beamforming training operation is to be performed on the directional link at time t1 based on the timing information included in or derived from receiving the trigger frame. Further, the STA can estimate the CFO associated with the wireless communication on the directional link based on the frequency information included in the trigger frame (such as the L-STF). Thus, the L-STF may not be present in each BFT packet transmitted on the directional link due to the beam management setup information carried in the trigger frame. In the example of FIG. 17A, each of the BFT packets is shown as a short training sequence (TS).

[0145]

[0175] At time t1, the AP starts a beamforming training operation by transmitting N training sequences in various TX beam directions on the directional link (as described with reference to FIGS. 9A and 10A). More specifically, at least one training sequence can be transmitted by each TX sector (such as TX sectors T1 to T7 in FIG. 6) associated with the AP. In some aspects, the STA can determine the sector ID of the (AP) sector from which the training sequence is transmitted based on the trigger frame received on the anchor link at time t0 and the timing of each training sequence (as indicated by the timestamp). In some other aspects, each of the training sequences can carry beam management information that explicitly signals one or more training parameters. More specifically, the beam management information can include any information that has not yet been signaled via the trigger frame. In some implementations, each of the training sequences can consist 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 implementations, each of the training sequences can consist of an LTF and a signal field (such as a non-legacy SIG) to carry additional beam management information (such as a training direction, a beam tracking request, a sector ID, the number of remaining training sequences (L) to be transmitted, or an antenna ID, etc.).

[0146]

[0176] The STA receives one or more of the training sequences and compares the signal power of the received training sequences. At time t2, the STA provides, on the directional link, feedback (FB) indicating which of the training sequences has the highest received signal power. In some implementations, the feedback can consist of a single LTF (such as a non-legacy LTF) designed to indicate the best sector ID. In some other implementations, the feedback can 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 can further train its RX antenna for RX beamforming based on the training sequences transmitted by the AP between times t1 and t2 (as described with reference to FIG. 9A). In some other implementations, the STA can perform additional packet exchanges with the AP between times t2 and t3 to train its RX antenna (as described with reference to FIGS. 10B or 10C). In some aspects, the AP can train its RX antenna for RX beamforming based on additional packet exchanges (such as those described with reference to FIGS. 9B, 10B, or 10C). In some other aspects, the STA can train its TX antenna for TX beamforming based on additional packet exchanges (such as those described with reference to FIGS. 9B or 10A).

[0147]

[0177] FIG. 18 shows a flowchart of an exemplary process 1800 for wireless communication that supports 60 GHz beam management for WLAN. In some implementations, process 1800 may be performed by an AP, such as any one of APs 102 or 502 described above with reference to FIGS. 1 and 5A, respectively, or by a wireless communication device operating within the AP. In some other implementations, process 1800 may be performed by a STA, such as any one of STAs 104 or 504 described above with reference to FIGS. 1 and 5B, respectively, or by a wireless communication device operating within the STA.

[0148]

[0178] In some implementations, process 1800 begins, at block 1802, by transmitting, on a first wireless communication link, N BFT packets in N respective TX beam directions, each of the N BFT packets including a PHY preamble that carries respective beam management information indicating the TX beam direction in which the BFT packet is transmitted. At block 1804, process 1800 proceeds to receive, from a response device, a first feedback associated with a first TX beam direction of the N TX beam directions. At block 1806, process 1800 proceeds to transmit a PPDU on the first wireless communication link in the first TX beam direction.

[0149]

[0179] In some aspects, process 1800 may further include associating with a response device via a second wireless communication link, and the N BFT packets are transmitted on the first wireless communication link based on associating with the response 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.

[0150]

[0180] In some implementations, each of the N BFT packets can consist of only the PHY preamble. In some implementations, the beam management information can include at least one of the PPDU type, the training direction, the beam tracking request, the number N of BFT packets, the number of BFT packets remaining to be transmitted, the TX sector ID or TX antenna ID associated with the TX beam direction in which the BFT packet is transmitted, or the number of RX sectors or RX antennas associated with the wireless communication device. In some aspects, the first feedback can be carried in the PHY preamble of the PPDU. In some implementations, the first feedback can include the TX sector ID or TX antenna ID indicated by the BFT packet transmitted in the first TX beam direction, the SNR report, or the number of RX sectors or RX antennas associated with the response device.

[0151]

[0181] In some aspects, process 1800 can further include retransmitting N BFT packets in each of the N TX beam directions on the first wireless communication link based on the number (M) of RX sectors associated with the response device. In such aspects, each of the N BFT packets can be transmitted M times in each of the respective TX beam directions. In some aspects, process 1800 can further include receiving some (K) BFT packets each carrying beam management information indicating each of the beam directions associated with the received BFT packets on the first wireless communication link. Measuring the signal power of each of the K received BFT packets and transmitting, to the response device, a second feedback associated with the received BFT packet having the highest signal power among the measured signal powers. In such aspects, the first feedback can be carried in the K received BFT packets.

[0152]

[0182] In some aspects, process 1800 may further include receiving one or more training signals on a first wireless communication link, where each of the one or more training signals is received via a plurality of antennas tuned to respective RX beam directions, measuring the power of each of the L received training signals, and receiving a PPDU from a response device via the plurality of antennas tuned to the RX beam direction of the training signal having the highest signal power among the measured signal powers. In some implementations, each of the plurality of training signals may represent a respective PPDU. In some other implementations, each of the plurality of training signals may represent a respective TRN of the same PPDU.

[0153]

[0183] FIG. 19 shows a flowchart illustrating an exemplary process 1900 for wireless communication supporting 60 GHz beam management for a WLAN. In some implementations, process 1900 may be executed by an AP operating as an AP such as any one of AP102 or 502, described above with reference to FIGS. 1 and 5A respectively, or by a wireless communication device operating within the AP. In some other implementations, process 1900 may be executed by a STA operating as a STA such as any one of STA104 and 504, described with reference to FIGS. 1 and 5B respectively, or by a wireless communication device within the STA.

[0154]

[0184] In some implementations, process 1900 begins in block 1902 by receiving several (N) BFT packets on a first wireless communication link, each of the N BFT packets including a PHY preamble that carries beam management information indicating a respective beam direction associated with the received BFT packet. In block 1904, process 1900 proceeds to measure the signal power of each of the received BFT packets. In block 1906, process 1900 proceeds to transmit, to the starting device, a first feedback associated with the received BFT packet having the highest signal power among the measured signal powers. In block 1908, process 1900 proceeds to receive a PPDU on the first wireless communication link based on the first feedback.

[0155]

[0185] In some aspects, process 1900 may further include associating with the starting device via a second wireless communication link, and the N BFT packets are received on the first wireless communication link based on associating with the starting 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.

[0156]

[0186] 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 a PPDU type, a training direction, a beam tracking request, the number of BFT packets transmitted by the starting device, the number of BFT packets remaining to be transmitted, a TX sector ID or TX antenna ID associated with the beam direction, or the number of RX sectors or RX antennas associated with the starting 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 having the highest signal power, an SNR report, or the number of RX sectors or RX antennas associated with the wireless communication device.

[0157]

[0187] In some aspects, the N BFT packets may be received via a plurality of antennas tuned to several (M) RX beam directions. In some implementations, at least one of the N BFT packets is received multiple times based on tuning a plurality of antennas in a plurality of RX beam directions out of the M RX beam directions, respectively. In some aspects, process 1900 may further include transmitting several (K) BFT packets in each of K TX beam directions on a first wireless communication link. Receiving a second feedback associated with a first TX beam direction out of the K TX beam directions from the starting device, and transmitting a PPDU in the first TX beam direction on the first wireless communication link. In some implementations, the first feedback may be carried in the K transmitted BFT packets.

[0158]

[0188] In some aspects, process 1900 may further include receiving one or more training signals on a first wireless communication link, where each of the one or more training signals is received via a plurality of antennas tuned to respective RX beam directions. Measuring the signal power of each of the received one or more training signals, and receiving a PPDU from a starting device via a plurality of antennas tuned to the RX beam direction of the training signal having the highest signal power among the measured signal powers. In some implementations, each of the plurality of training signals may represent a respective PPDU. In some other implementations, each of the plurality of training signals may represent a respective TRN of the same PPDU.

[0159]

[0189] FIG. 20 shows a block diagram of an exemplary wireless communication device 2000 according to some implementations. In some implementations, wireless communication device 2000 is configured to implement process 1800 described above with reference to FIG. 18. Wireless communication device 2000 may be an exemplary implementation of wireless communication device 400 described above with reference to FIG. 4. For example, 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 (IEEE802.11) modem or a cellular modem).

[0160]

[0190] The wireless communication device 2000 includes a receiving component 2010, a communication manager 2020, and a transmitting component 2030. The communication manager 2020 further includes a beam training start component 2022. A part of the beam training start component 2022 may be implemented at least partially in hardware or firmware. In some embodiments, the beam training start component 2022 is implemented at least partially as software stored in a memory (such as memory 408). For example, parts of the beam training start component 2022 may be implemented as non-transitory instructions (or "code") executable by a processor (such as processor 406) to perform the functions or operations of the respective components.

[0161]

[0191] The receiving component 2010 is configured to receive an RX signal from one or more other wireless communication devices via a wireless channel. The transmitting component 2030 is configured to transmit a TX signal to one or more other wireless communication devices via a wireless channel. The communication manager 2020 is configured to control or manage communication with one or more other wireless communication devices. In some implementations, the beam training start component 2022 can transmit N BFT packets in N TX beam directions respectively on a first wireless communication link, and each of the N BFT packets includes a PHY preamble carrying respective beam management information indicating the TX beam direction in which the BFT packet is transmitted. In some implementations, the receiving component 2010 may receive feedback associated with a first TX beam direction among the N TX beam directions from a response device. In some implementations, the transmitting component 2030 may transmit a PPDU on the first wireless communication link in the first TX beam direction.

[0162]

[0192] Figure 21 shows a block diagram of an exemplary wireless communication device 2100 according to some implementations. In some implementations, the wireless communication device 2100 is configured to perform process 1900 described above with reference to FIG. 19. The wireless communication device 2100 can be an exemplary implementation of the wireless communication device 400 described above with reference to FIG. 4. For example, the wireless communication device 2100 can 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).

[0163]

[0193] The wireless communication device 2100 includes a receiving component 2110, a communication manager 2120, and a transmitting component 2130. The communication manager 2120 further includes a beam training response component 2122. A portion of the beam training response component 2122 may be implemented at least partially in hardware or firmware. In some aspects, the beam training response component 2122 is implemented at least partially as software stored in a memory (such as memory 408). For example, portions of the beam training response component 2122 can be implemented as non-transitory instructions (or "code") executable by a processor (such as processor 406) to perform the functions or operations of the respective components.

[0164]

[0194] The receiving component 2110 is configured to receive an RX signal from one or more other wireless communication devices via a wireless channel. The transmitting component 2130 is configured to transmit a TX signal to one or more other wireless communication devices via a wireless channel. The communication manager 2120 is configured to control or manage communication with one or more other wireless communication devices. In some implementations, the beam training response component 2122 can receive some (N) BFT packets on a first wireless communication link, measure the signal power of each of the received BFT packets, and each of the N BFT packets includes a PHY preamble that carries beam management information indicating the respective beam direction associated with the received BFT packet. In some implementations, the transmitting component 2130 may transmit feedback associated with the received BFT packet having the highest signal power among the measured signal powers to the initiating device. In some implementations, the receiving component 2110 may receive a PPDU on the first wireless communication link based on the first feedback.

[0165]

[0195] In the following numbered clauses, implementation examples are described. Clause 1 A method for wireless communication by a wireless communication device, comprising: transmitting, on a first wireless communication link, respectively, N beamforming training (BFT) packets in N transmission (TX) beam directions, each of the N BFT packets including a PHY preamble that carries respective beam management information indicating the TX beam direction in which the BFT packet is transmitted; receiving, from a response device, first feedback associated with a first TX beam direction among the N TX beam directions; transmitting, in the first TX beam direction, a physical layer convergence protocol (PLCP) protocol data unit (PPDU) on the first wireless communication link. Clause 2 Associating with a response device via a second wireless communication link, wherein N BFT packets are transmitted on a first wireless communication link based on associating with the response device via the second wireless communication link, the method according to clause 1 further comprising the associating. Clause 3 The method according to any one 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. Clause 4 Each of the N BFT packets consists of only a PHY preamble, the method according to any one of clauses 1 to 3. Clause 5 The beam management information includes at least one of a PPDU type, a training direction, a beam tracking requirement, a number N of BFT packets, a number of remaining BFT packets to be transmitted, a TX sector identifier (ID) or a TX antenna ID associated with a TX beam direction in which a BFT packet is transmitted, or a number of RX sectors or RX antennas associated with a wireless communication device, the method according to any one of clauses 1 to 4. Clause 6 The first feedback is carried in the PHY preamble of the PPDU, the method according to any one of clauses 1 to 5. Clause 7 The first feedback includes a TX sector ID or a TX antenna ID indicated by a BFT packet transmitted in a first TX beam direction, a signal-to-noise ratio (SNR) report, or a number of RX sectors or RX antennas associated with the response device, the method according to any one of clauses 1 to 6. Clause 8 The method according to any one of clauses 1 to 7 further comprising retransmitting N BFT packets in N TX beam directions respectively on the first wireless communication link based on a number (M) of RX sectors associated with the response device. Clause 9 Each of the N BFT packets is transmitted M times in each respective TX beam direction, the method according to any one of clauses 1 to 8. Clause 10 Receiving, on a first wireless communication link, several (K) BFT packets that carry beam management information indicating, for each of the received BFT packets, a respective beam direction; Measuring the signal power of each of the K received BFT packets; Further comprising transmitting, to a response device, a second feedback associated with a received BFT packet having the highest signal power among the measured signal powers, the method according to any one of clauses 1 to 9. Clause 11 The first feedback is the method according to any one of clauses 1 to 10, carried by K received BFT packets. Clause 12 Receiving, on a first wireless communication link, one or more training signals, wherein each of the one or more training signals is received via a plurality of antennas tuned to respective RX beam directions; Measuring the signal power of each of the L received training signals; Further comprising receiving, from a response device, a PPDU via a plurality of antennas tuned to an RX beam direction in which a training signal having the highest signal power among the measured signal powers is received, the method according to any one of clauses 1 to 11. Clause 13 Each of the plurality of training signals is the method according to any one of clauses 1 to 12, representing a respective PPDU. Clause 14 Each of the plurality of training signals is the method according to any one of clauses 1 to 12, representing a respective training (TRN) field of the same PPDU. Clause 15 A wireless communication device, At least one memory; At least one processor communicatively coupled to the at least one memory, the at least one processor being configured to cause the wireless communication device to execute any one or more of the methods of clauses 1 to 14, the wireless communication device comprising the at least one processor. Clause 16 A method for wireless communication by a wireless communication device, comprising: Receiving, on a first wireless communication link, several (N) beamforming training (BFT) packets, each of the N BFT packets including a physical layer (PHY) preamble that carries beam management information indicating a respective beam direction associated with the received BFT packet; Measuring the signal power of each of the received BFT packets; Transmitting, to a starting device, a first feedback associated with the received BFT packet having the highest signal power among the measured signal powers; Receiving, on the first wireless communication link, a physical layer convergence protocol (PLCP) protocol data unit (PPDU) based on the first feedback. Clause 17 Associating with the starting device via a second wireless communication link, the method according to clause 16, further comprising: the N BFT packets being received on the first wireless communication link based on the association with the starting device via the second wireless communication link. Clause 18 The method according to any one 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. Clause 19 Each of the N BFT packets consists of only a PHY preamble, the method according to any one of clauses 16 to 18. Clause 20 The beam management information includes at least one of a PPDU type, a training direction, a beam tracking request, the number of BFT packets transmitted by the starting device, the number of BFT packets remaining to be transmitted, a transmission (TX) sector identifier (ID) or TX antenna ID associated with the beam direction, or the number of receive (RX) sectors or RX antennas associated with the starting device, the method according to any one of clauses 16 to 19. Clause 21 The first feedback is the method described in any of Clauses 16 to 20, which is carried in the PHY preamble of the PPDU. Clause 22 The first feedback is the method described in any of Clauses 16 to 21, including the TX sector ID or TX antenna ID indicated by the received BFT packet having the highest signal power, the signal-to-noise ratio (SNR) report, or the number of RX sectors or RX antennas associated with the wireless communication device. Clause 23 The N BFT packets are received via a plurality of antennas synchronized to a plurality (M) of RX beam directions, according to the method described in any of Clauses 16 to 22. Clause 24 At least one of the N BFT packets is received multiple times based on synchronizing a plurality of antennas in a plurality of RX beam directions among the M RX beam directions, according to the method described in any of Clauses 16 to 23. Clause 25 On the first wireless communication link, transmitting some (K) BFT packets in each of the K TX beam directions, Receiving, from the starting device, a second feedback associated with the first TX beam direction among the K TX beam directions, On the first wireless communication link, further including transmitting a PPDU in the first TX beam direction, according to the method described in any of Clauses 16 to 24. Clause 26 The first feedback is the method described in any of Clauses 16 to 25, which is carried in the K transmitted BFT packets. Clause 27 Receiving, on the first wireless communication link, one or more training signals, where each of the one or more training signals is received via a plurality of antennas synchronized to respective RX beam directions, Measuring the signal power of each of the one or more received training signals, Receiving a PPDU from a start device via a plurality of antennas tuned to an RX beam direction in which a training signal having the highest signal power among the measured signal powers is received; and, the method according to any one of clauses 16 to 26. Clause 28 Each of the plurality of training signals is a method according to any one of clauses 16 to 27, representing a respective PPDU. Clause 29 Each of the plurality of training signals is a method according to any one of clauses 16 to 27, representing a respective training (TRN) field of the same PPDU. Clause 30 A wireless communication device, at least one memory; at least one processor communicatively coupled to the at least one memory, the at least one processor being configured to cause the wireless communication device to perform any one or more of the methods of clauses 16 to 29; and, a wireless communication device comprising the at least one processor.

[0166]

[0196] As used herein, the phrase referring to a list of items "at least one of" or "one or more of" refers to any combination of those items, including a single member. For example, "at least one of a, b, or c" is intended to encompass the possibilities of a only, b only, c only, 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 construed in an inclusive sense unless explicitly stated otherwise. For example, "based on" may be used interchangeably with "at least partially based on" unless explicitly stated otherwise. Specifically, unless the phrase refers to "only based on 'a'" or an equivalent in the context, whatever "based on 'a'" or "at least partially based on 'a'" may be, it may be based on only "a" or a combination of "a" with one or more other factors, conditions, or information.

[0167]

[0197] With respect to the implementations disclosed herein, the various exemplary components, logics, logical blocks, modules, circuits, operations, and algorithmic processes described may be implemented as electronic hardware, firmware, software, or any combination of hardware, firmware, or software, including the structures disclosed herein and their structural equivalents. The interchangeability of hardware, firmware, and software is schematically described from a functional perspective and is illustrated in the various exemplary components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system.

[0168]

[0198] Various modifications to the implementations described in this disclosure may become readily apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of the disclosure. Accordingly, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with the disclosure, the principles disclosed herein, and the novel features.

[0169]

[0199] Additionally, the various features described herein in the context of separate implementations may also be implemented in combination within a single implementation. Conversely, the various features described herein in the context of a single implementation may also be implemented separately, or in any suitable sub-combination, in multiple implementations. Thus, although features may be described above as acting in a particular combination and even claimed as such initially, in some cases, one or more features from a claimed combination may be deleted from that combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

[0170]

[0200] Similarly, the operations are illustrated in the drawings in a particular order, but this should not be understood as requiring that such operations be performed in the particular order shown or in a sequential order, or that all of the operations shown be performed. Further, the drawings may schematically illustrate another exemplary process in the form of a flowchart or a flow diagram. However, other operations not shown may be incorporated into the exemplary process that is schematically shown. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the operations shown. In some situations, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementation forms described above should not be understood as requiring such separation in all implementation forms, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Claims

1. A method of wireless communication carried out by a first multilink wireless communication device, Communicating one or more frames for association with the second multilink wireless communication device via the first wireless communication link among a plurality of wireless communication links supported by the first multilink wireless communication device and the second multilink wireless communication device, Associating with the second multilink wireless communication device via the first wireless communication link, the second wireless communication link among the plurality of wireless communication links transmits N beamforming training (BFT) packets in several (N) transmit (TX) beam directions, and each of the N BFT packets includes a physical layer (PHY) preamble that carries beam management information indicating the respective TX beam direction from which the BFT packet is transmitted. Receiving a first feedback from the second multilink wireless communication device associated with the first TX beam direction among the N TX beam directions, A method comprising transmitting a Physical Layer Convergence Protocol (PLCP) protocol data unit (PPDU) over the second wireless communication link in the first TX beam direction in accordance with the first feedback.

2. (a) The first wireless communication link operates at a first carrier frequency below 7 GHz, and the second wireless communication link operates at a second carrier frequency above 7 GHz. (b) Each of the N BFT packets consists only of the PHY preamble, or (c) 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 transmitted, a TX sector identifier (ID) or TX antenna ID associated with each of the TX beam directions to which BFT packets are transmitted, or the number of receiving (RX) sectors or RX antennas associated with the first multilink wireless communication device. The method according to claim 1, wherein at least one of the following:

3. The method according to claim 2, wherein the first feedback is conveyed in the PHY preamble of the PPDU.

4. The method according to claim 3, wherein the first feedback includes the TX sector ID or TX antenna ID indicated by a BFT packet transmitted 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 second multilink communication device.

5. (a) Retransmitting the N BFT packets on the second wireless communication link in each of the N TX beam directions according to the number (M) of RX sectors associated with the second multilink communication device, (b) Receiving several (K) BFT packets on the second wireless communication link, each carrying beam management information indicating the beam direction associated with the received BFT packet, Measuring the signal power of each of the K BFT packets, Transmitting to the second multilink wireless communication device a second feedback associated with the received BFT packet having the highest signal power among the measured signal powers, or (c) Receiving one or more training signals on the second wireless communication link, and each of the one or more training signals being received via a plurality of antennas tuned to the respective RX beam directions, Measuring the signal power of each of the one or more training signals, The PPDU is received from the second multilink wireless communication device via the plurality of antennas tuned to the RX beam direction from which the training signal having the highest signal power among the measured signal powers is received. The method according to claim 1, further comprising at least one of the following.

6. (a) Each of the N BFT packets is transmitted M times in each of the TX beam directions, (b) The first feedback is carried in the K BFT packets, The method according to claim 5, wherein at least one of the following is the method according to claim 5.

7. The method according to claim 6, wherein each of the one or more training signals represents either their respective PPDU or their respective training (TRN) fields of the same PPDU.

8. A first multilink wireless communication device for wireless communication, At least one memory, The device comprises at least one processor communicatively coupled to the at least one memory, wherein the at least one processor is connected to the first multilink wireless communication device. Communicating one or more frames for association with the second multilink wireless communication device via the first wireless communication link among a plurality of wireless communication links supported by the first multilink wireless communication device and the second multilink wireless communication device, Associating the second multilink wireless communication device via the first wireless communication link, several (N) beamforming training (BFT) packets are transmitted on the second wireless link of the plurality of wireless communication links in N transmit (TX) beam directions, and each of the N BFT packets includes a physical layer (PHY) preamble that carries beam management information indicating the respective beam direction from which the BFT packet is transmitted. Receiving a first feedback from the second multilink wireless communication device associated with the first TX beam direction among the N TX beam directions, In accordance with the first feedback, a Physical Layer Convergence Protocol (PLCP) protocol data unit (PPDU) is transmitted over the second multilink wireless communication link in the first TX beam direction, A wireless communication device configured to perform the following actions.

9. A method of wireless communication carried out by a first multilink wireless communication device, Communicating one or more frames for association with the second multilink communication device via the first wireless communication link among a plurality of wireless communication links supported by the first multilink communication device and the second multilink wireless communication device, The system includes, in relation to the second multilink wireless communication device via the first wireless communication link, receiving several (N) beamforming training (BFT) packets on the second wireless communication link among the plurality of wireless communication links, and each of the N BFT packets includes a physical layer (PHY) preamble that carries beam management information indicating the respective beam direction associated with the BFT packet. The signal power of each of the N BFT packets is measured, Transmitting a first feedback associated with the received BFT packet having the highest signal power among the measured signal powers to the second multilink wireless communication device, A method comprising receiving a Physical Layer Convergence Protocol (PLCP) protocol data unit (PPDU) on the first wireless communication link in accordance with the first feedback.

10. (a) The first wireless communication link operates at a first carrier frequency below 7 GHz, and the second wireless communication link operates at a second carrier frequency above 7 GHz. (b) Each of the N BFT packets consists only of the PHY preamble, (c) The beam management information includes at least one of the following: PPDU type, training direction, beam tracking request, number of BFT packets transmitted by the second multilink wireless communication device, number of the N BFT packets remaining to be transmitted, transmit (TX) sector identifier (ID) or TX antenna ID associated with each of the beam directions, or number of receive (RX) sectors or RX antennas associated with the second multilink wireless communication device, or (d) The N BFT packets are received via a number of antennas (M) tuned to the RX beam direction. The method according to claim 9, wherein at least one of the following is the method according to claim 9.

11. The method according to claim 10, wherein the first feedback is conveyed in the PHY preamble of the PPDU.

12. (a) Transmitting several (K) BFT packets in K TX beam directions on the second wireless communication link, Receiving a second feedback from the second multilink wireless communication device associated with the first TX beam direction among the K TX beam directions, Transmitting a PPDU in the direction of the first TX beam over the second wireless communication link, (b) Receiving one or more training signals on the second wireless communication link, and each of the one or more training signals being received via a plurality of antennas tuned to the respective RX beam directions, Measuring the signal power of each of the one or more training signals, The PPDU is received from the second multilink wireless communication device via the plurality of antennas tuned to the RX beam direction to receive the training signal having the highest signal power among the measured signal powers. The method according to claim 9, further comprising at least one of the following.

13. (a) Each of the one or more training signals represents a respective PPDU, (b) Each of the one or more training signals represents the respective training (TRN) field of the same PPDU. The method according to claim 12, wherein at least one of the following is the method according to claim 12.

14. A first multilink wireless communication device for wireless communication, At least one memory, The device comprises at least one processor communicatively coupled to the at least one memory, wherein the at least one processor is connected to the first multilink wireless communication device. Communicating one or more frames for association with the second multilink wireless communication device via the first wireless communication link among a plurality of communication links supported by the first multilink wireless communication device and the second multilink wireless communication device, Associating with the second multilink wireless communication device via the first wireless communication link, the second wireless communication link among the plurality of wireless communication links receives several (N) beamforming training (BFT) packets, each of the N BFT packets includes a physical layer (PHY) preamble that carries beam management information indicating the respective beam direction associated with the received BFT packet. The signal power of each of the N BFT packets is measured, Transmitting a first feedback associated with the received BFT packet having the highest signal power among the measured signal powers to the second multilink wireless communication device, In accordance with the first feedback, a Physical Layer Convergence Protocol (PLCP) protocol data unit (PPDU) is received on the second wireless communication link, A wireless communication device configured to perform the following actions.

15. A non-temporary computer-readable medium that stores code, which, when executed by a processor, causes the processor to perform the method according to any one of claims 1 to 7 and 9 to 13.

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