60GHz operating mode for wireless local area network (WLAN)

Abstract

The present disclosure provides methods, devices, and systems for increasing carrier frequency for wireless communications in a wireless local area network (WLAN). More specifically, some implementations relate to BSS discovery and associated techniques that support wireless communications on carrier frequencies above 7 GHz. In some aspects, an access point (AP) may communicate using beamforming on a wireless communication link ("directional link") operating at a carrier frequency above 7 GHz while offloading BSS discovery and association procedures required to support such communications onto a wireless communication link ("anchor link") operating at a carrier frequency below 7 GHz. In some implementations, the AP may perform a beamforming training operation with an STA over the directional link when associated with the STA over the anchor chain. In such implementations, the AP may communicate with the STA over the directional link using a beam derived from the beamforming training operation.

Description

[0001] Cross-references

[0002] This patent application claims priority to U.S. patent application No. 17 / 738,892, filed by Yang et al. on May 6, 2022, entitled “60GHZ OPERATING MODE FOR WIRELESS LOCAL AREA NETWORKS (WLANS)”, which has been assigned to the assignee of this application and is expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to wireless communications, and more particularly, to a 60 GHz mode of operation for a wireless local area network (WLAN). Background Art

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

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

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

[0007] An innovative aspect of the subject matter described in the present disclosure may be implemented as a method of wireless communication. The method may be performed by a wireless access point (AP) and may include sending one or more management frames on a first wireless communication link that announces a basic service set (BSS) associated with the AP; associating with a wireless station (STA) through the first wireless communication link based on the one or more management frames; performing a beamforming training operation with the STA through a second wireless communication link based on associating with the STA through the first wireless communication link; and communicating with the STA through the second wireless communication link using a beam based on the beamforming training operation. In some specific implementations, the first wireless communication link may operate at a carrier frequency lower than 7 GHz, and the second wireless communication link may operate at a carrier frequency higher than 7 GHz.

[0008] In some aspects, the method may further include exchanging beam management setup information with the STA via the first wireless communication link, wherein the beam management setup information signals the start of the beamforming training operation. In some implementations, the beam management setup information may include frequency information indicating a carrier frequency offset (CFO) associated with wireless communication on the second wireless communication link. In some implementations, the beam management setup information may include timing information indicating the timing of wireless communication on the second wireless communication link. In some implementations, the method may further include sending scheduling information on the first wireless communication link, the scheduling information allocating a service period (SP) for communication with the STA via the second wireless communication link.

[0009] In some aspects, the execution of the beamforming training operation may include sending multiple physical layer (PHY) convergence protocol (PLCP) protocol data units (PPDUs) in multiple directions on the second wireless communication link, wherein each of the multiple PPDUs consists of a single PHY training field; and receiving feedback from the STA in response to sending the multiple PPDUs, wherein the feedback indicates the direction for tuning multiple antennas. In some specific implementations, the AP may communicate with the STA through the second wireless communication link via the multiple antennas tuned in the direction indicated by the feedback. In some specific implementations, the feedback may be carried in a PPDU consisting of a single PHY training field. In some other specific implementations, the feedback may be carried in a PPDU consisting of a single PHY training field and a single PHY signal field. In some specific implementations, the feedback may be received on the second wireless communication link. In some other specific implementations, the feedback may be received on the first wireless communication link.

[0010] Another innovative aspect of the subject matter described in the present disclosure may be implemented in an AP. In some implementations, the AP may include at least one memory and at least one processor, the at least one processor being communicatively coupled to the at least one memory and configured to cause the AP to perform operations including sending one or more management frames announcing a BSS associated with the AP over a first wireless communication link; associating with a STA over the first wireless communication link based on the one or more management frames; performing a beamforming training operation with the STA over a second wireless communication link based on associating with the STA over the first wireless communication link; and communicating with the STA over the second wireless communication link using a beam based on the beamforming training operation. In some implementations, the AP may also include a local oscillator (LO) configured to drive a carrier frequency associated with each of the first wireless communication link and the second wireless communication link. In some implementations, the AP may also include a clock configured to control the timing of communications over each of the first wireless communication link and the second wireless communication link.

[0011] Another innovative aspect of the subject matter described in the present disclosure may be implemented as a method of wireless communication. The method may be performed by a STA and may include receiving one or more management frames on a first wireless communication link that announces a BSS associated with an AP; associating with the AP through the first wireless communication link based on the one or more management frames; performing a beamforming training operation with the AP through a second wireless communication link based on associating with the AP through the first wireless communication link; and communicating with the AP through the second wireless communication link using a beam based on the beamforming training operation. In some specific implementations, the first wireless communication link may operate at a carrier frequency lower than 7 GHz, and the second wireless communication link may operate at a carrier frequency higher than 7 GHz.

[0012] In some aspects, the method may further include exchanging beam management setup information with the AP over the first wireless communication link, the beam management setup information signaling the start of the beamforming training operation. In some implementations, the beam management setup information may include frequency information indicating a CFO associated with wireless communication on the second wireless communication link. In some implementations, the beam management setup information may include timing information indicating the timing of wireless communication on the second wireless communication link. In some implementations, the method may further include receiving scheduling information on the first wireless communication link, the scheduling information allocating an SP for communication with the AP over the second wireless communication link.

[0013] In some aspects, the execution of the beamforming training operation may include sending multiple PPDUs in multiple directions on the second wireless communication link, each of which consists of a single PHY training field; and receiving feedback from the AP in response to sending the multiple PPDUs, wherein the feedback indicates the direction for tuning multiple antennas. In some specific implementations, the STA may communicate with the AP through the second wireless communication link via the multiple antennas tuned in the direction indicated by the feedback. In some specific implementations, the feedback may be carried in a PPDU consisting of a single PHY training field. In some other specific implementations, the feedback may be carried in a PPDU consisting of a single PHY training field and a single PHY signal field. In some specific implementations, the feedback may be received on the second wireless communication link. In some other specific implementations, the feedback may be received on the first wireless communication link.

[0014] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a STA. In some implementations, the STA may include at least one memory and at least one processor, the at least one processor being communicatively coupled to the at least one memory and configured to cause the STA to perform operations including receiving one or more management frames announcing a BSS associated with an AP over a first wireless communication link; associating with the AP over the first wireless communication link based on the one or more management frames; performing a beamforming training operation with the AP over a second wireless communication link based on associating with the AP over the first wireless communication link; and communicating with the AP over the second wireless communication link using a beam based on the beamforming training operation. In some implementations, the STA may also include a LO configured to drive a carrier frequency associated with each of the first wireless communication link and the second wireless communication link. In some implementations, the STA may also include a clock configured to control the timing of communications over each of the first wireless communication link and the second wireless communication link. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Details of one or more specific implementations of the subject matter described in the present disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the specification, drawings, and claims. Note that the relative dimensions in the drawings may not be drawn to scale.

[0016] Figure 1 A schematic diagram of an example wireless communication network is shown.

[0017] Figure 2A Example protocol data units (PDUs) that can be used for communications between an access point (AP) and one or more wireless stations (STAs) are shown.

[0018] Figure 2B Shows Figure 2A Example fields in a PDU.

[0019] Figure 3 An example physical layer convergence protocol (PLCP) protocol data unit (PPDU) that can be used for communications between an AP and one or more STAs is shown.

[0020] Figure 4 A block diagram of an example wireless communication device is shown.

[0021] Figure 5A A block diagram of an example AP is shown.

[0022] Figure 5B A block diagram of an example STA is shown.

[0023] Figure 6 An example communication environment including an AP and a STA according to some implementations is shown.

[0024] Figure 7 An example communication system including an AP multi-link device (MLD) and a non-AP MLD is shown according to some implementations.

[0025] Figure 8 A sequence diagram depicting example multi-link communications between an AP and a STA is shown according to some implementations.

[0026] Fig. 9 A timing diagram depicting example wireless communications between an AP and a STA over a directional link is shown according to some implementations.

[0027] Fig.10 A timing diagram depicting example wireless communications between an AP and a STA over an anchor link and a directional link is shown according to some implementations.

[0028] Fig.11 A block diagram of an example transmit (TX) processing chain for a wireless communication device is shown according to some implementations.

[0029] Fig. 12A An example PPDU formatted according to the legacy PPDU format is shown.

[0030] Fig. 12B According to some specific implementations, Fig. 12A An example of a PPDU format is depicted in FIG. 10A , 10B , 10C , and 10D . FIG.

[0031] Fig.13 A block diagram of an example analog front end (AFE) for a wireless communication device is shown according to some implementations.

[0032] Fig.14A A timing diagram depicting example wireless communications between an AP and a STA over an anchor link and a directional link is shown according to some implementations.

[0033] Fig. 14B Another timing diagram depicting example wireless communications between an AP and a STA over an anchor link and a directional link is shown according to some implementations.

[0034] Fig.15 A flow chart illustrating an example process for wireless communications supporting a 60 GHz mode of operation for a wireless local area network (WLAN) is shown.

[0035] Fig.16 A flow chart illustrating an example process for wireless communications supporting a 60 GHz mode of operation for a WLAN is shown.

[0036] Fig.17 A block diagram of an example AP is shown according to some implementations.

[0037] Fig.18 A block diagram of an example STA according to some implementations is shown.

[0038] The same reference numbers and designations in different drawings represent the same elements. DETAILED DESCRIPTION

[0039] The following description is directed to certain specific implementations in order to describe the innovative aspects of the present disclosure. However, one of ordinary skill in the art will readily recognize that the teachings herein can be applied in a variety of different ways. The specific implementations described may be implemented in a manner that can be implemented in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, the IEEE 802.15 standard, the Bluetooth Special Interest Group (SIG) standard, or the like. The described implementations may be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals in accordance with one or more of the Long Term Evolution (LTE), 3G, 4G, or 5G (New Radio (NR)) standards, or the like released by the Third Generation Partnership Project (3GPP). The described implementations may be implemented in any device, system, or network capable of transmitting and receiving RF signals in accordance with one or more of the following technologies or techniques: code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), single user (SU) multiple input multiple output (MIMO), and multi-user (MU) MIMO. The described implementations may also be implemented using other wireless communication protocols or RF signals suitable for use in one or more of a wireless personal area network (WPAN), a wireless local area network (WLAN), a wireless wide area network (WWAN), or an Internet of Things (IOT) network.

[0040] As described above, new WLAN communication protocols are being developed to implement enhanced features for wireless communications on carrier frequencies above 7 GHz (such as in the 60 GHz or 45 GHz bands). However, wireless communications on higher carrier frequencies may suffer from greater phase noise and path loss than wireless communications on lower frequency bands. Aspects of the present disclosure recognize that analog beamforming (using a large number of antenna elements) can mitigate the effects of path loss and achieve a greater wireless communication range on carrier frequencies above 7 GHz. Analog beamforming is a wireless communication technique by which a transmitting device and a receiving device can adjust the gain and phase of their transmit (TX) antenna elements and receive (RX) antenna elements to achieve directionality in wireless communications. For example, a transmitting device may tune a set of TX antennas to focus the energy of a transmitted signal in a particular direction (referred to as "TX beamforming"). Similarly, a receiving device may tune a set of RX antennas to focus the energy of a received signal in a particular direction (referred to as "RX beamforming"). When TX beamforming is used in combination with RX beamforming, optimal beamforming gain may be achieved (such as optimal beamforming gain may be required to overcome path loss in the 60 GHz band). The process by which the transmitting and receiving devices tune their antennas for beamforming is referred to as a "beamforming training" operation.

[0041] Existing versions of the IEEE 802.11 standard define a basic service set (BSS) discovery protocol for carrier frequencies below 7 GHz (also referred to as the "below 7 GHz" band), whereby a wireless access point (AP) announces its BSS in a management frame (such as a beacon or a probe response) sent omnidirectionally. Any wireless station (STA) within the coverage area of ​​the AP can receive such a management frame and request to associate with the BSS. As described above, omnidirectional communications suffer from significant path loss at carrier frequencies above 7 GHz. Although beamforming can help offset the path loss associated with wireless communications at carrier frequencies above 7 GHz, the directionality of the beamformed signal (or "beam") presents challenges to BSS discovery and association. For example, beamforming gain can only be achieved when the AP sends a beam in the direction of a particular STA (or in a direction associated with a desired link budget). However, prior to discovery, the AP typically does not know the direction of the STA. Therefore, a new mode of BSS discovery (and association) is needed to support wireless communications at carrier frequencies above 7 GHz.

[0042] Various aspects generally relate to increasing carrier frequencies for wireless communications in WLANs, and more specifically, to BSS discovery and association techniques that support wireless communications at carrier frequencies above 7 GHz. In some aspects, an AP may utilize multiple wireless communication links to facilitate various management and control functions for directional communications. More specifically, an AP may communicate using beamforming on a wireless communication link operating at a carrier frequency above 7 GHz (also referred to as a "directional link"), while offloading the BSS discovery and association procedures required to support such communications to a wireless communication link operating at a carrier frequency below 7 GHz (also referred to as an "anchor link"). In some implementations, an AP may perform a beamforming training operation with a STA over the directional link while associating with the STA over the anchor link. In such implementations, the AP may communicate with the STA over the directional link using a beam derived from the beamforming training operation. In some aspects, the AP may further send a trigger frame over the anchor link that signals the start of the beamforming training operation and various control parameters associated with the beamforming training operation. In some implementations, the trigger frame may synchronize wireless communications on the anchor link with wireless communications on the directional link. For example, a trigger frame may provide a timing or frequency reference for wireless communications over a directional link.

[0043] Specific implementations of the subject matter described in the present disclosure may be implemented to achieve one or more of the following potential advantages. By utilizing a directional link for data communication (operating at a carrier frequency higher than 7 GHz) and an anchor link associated with the directional link for management and control functions (operating at a carrier frequency lower than 7 GHz), various aspects of the present disclosure may utilize existing WLAN communication protocols and hardware to support wireless communications on carrier frequencies higher than 7 GHz. As described above, existing BSS discovery and association operations may be performed using omnidirectional communications on carrier frequencies lower than 7 GHz. However, directional communications may benefit from enhanced features (such as wider bandwidth or higher data rates) on carrier frequencies higher than 7 GHz. By offloading the BSS discovery and association operations required to support wireless communications on a directional link to an anchor link, an AP may achieve the benefits of directional communications at a higher carrier frequency and omnidirectional communications for BSS discovery and association. By synchronizing wireless communications on an anchor link with wireless communications on a directional link, an AP may further reduce the overhead and delay associated with communicating on a directional link.

[0044] Figure 1 A block diagram of an example wireless communication network 100 is shown. According to some aspects, the wireless communication network 100 may be an example of a wireless local area network (WLAN) such as a Wi-Fi network (and will be referred to as WLAN 100 hereinafter). For example, the WLAN 100 may be a network that implements at least one of the IEEE 802.11 family of wireless communication protocol standards, such as standards defined by the IEEE 802.11-2020 specification or amendments thereof, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be. The WLAN 100 may include numerous wireless communication devices, such as an access point (AP) 102 and a plurality of stations (STAs) 104. Although only one AP 102 is shown, the WLAN network 100 may also include a plurality of APs 102.

[0045] Each STA 104 may also be referred to as a mobile station (MS), a mobile device, a mobile phone, a wireless phone, an access terminal (AT), a user equipment (UE), a subscriber station (SS), or a subscriber unit, among other possibilities. STA 104 may represent a variety of devices, such as mobile phones, personal digital assistants (PDAs), other handheld devices, netbooks, notebook computers, tablet computers, laptop computers, display devices (e.g., TVs, computer monitors, navigation systems, etc.), music or other audio or stereo equipment, remote control devices ("remote controls"), printers, kitchen or other home appliances, key fobs (e.g., for passive keyless entry and start (PKES) systems), and other possibilities.

[0046] A single AP 102 and the associated set of STAs 104 may be referred to as a basic service set (BSS), which is managed by the respective AP 102 . Figure 1 Additionally shown is an example coverage area 108 of the AP 102, which may represent a basic service area (BSA) of the WLAN 100. The BSS may be identified to users by a service set identifier (SSID) and may also be identified to other devices by a basic service set identifier (BSSID), which may be a medium access control (MAC) address of the AP 102. The AP 102 periodically broadcasts a beacon frame (“beacon”) including the BSSID to enable any STA 104 within the wireless range of the AP 102 to “associate” or re-associate with the AP 102 to establish or maintain a corresponding communication link 106 (hereinafter also referred to as a “Wi-Fi link”) with the AP 102. For example, the beacon may include an identification of a primary channel used by the corresponding AP 102 and a timing synchronization function for establishing or maintaining timing synchronization with the AP 102. The AP 102 may provide various STAs 104 in the WLAN with access to external networks via respective communication links 106 .

[0047] To establish a communication link 106 with the AP 102, each STA 104 is configured to perform passive or active scanning operations ("scanning") on frequency channels in one or more frequency bands (eg, 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). To perform passive scanning, the STA 104 listens for beacons transmitted by the corresponding AP 102 at periodic time intervals, referred to as target beacon transmission times (TBTTs), measured in time units (TUs), where one TU may be equal to 1024 microseconds (μs). To perform active scanning, the STA 104 generates and sequentially transmits probe requests on each channel to be scanned, and listens for probe responses from the AP 102. Each STA 104 may be configured to identify or select an AP 102 to associate with based on the scanning information obtained through passive or active scanning, and perform authentication and association operations to establish a communication link 106 with the selected AP 102. The AP 102 assigns an association identifier (AID) to the STA 104 at the end of the association operation, and the AP 102 uses the association identifier (AID) to track the STA 104.

[0048] As wireless networks become more and more common, a STA 104 may have the opportunity to select one of many BSSs within the range of the STA or to select among multiple APs 102 that together form an extended service set (ESS) (including multiple connected BSSs). An extended network station associated with a WLAN 100 may be connected to a wired or wireless distribution system that allows multiple APs 102 to be connected in such an ESS. In this way, a STA 104 may be covered by more than one AP 102 and may be associated with different APs 102 at different times for different transmissions. Additionally, after associating with an AP 102, the STA 104 may also be configured to periodically scan its surroundings to find a more appropriate AP 102 to associate with. For example, a STA 104 that is moving relative to its associated AP 102 may perform a "roaming" scan to find another AP 102 with a more suitable network characteristic (such as a larger received signal strength indicator (RSSI) or a reduced traffic load).

[0049] In some cases, STA 104 may form a network without AP 102 or other equipment other than STA 104 itself. An example of such a network is an ad hoc network (or 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 WLAN 100). In such a specific implementation, although STA 104 may be able to communicate with each other through AP 102 using communication link 106, STA 104 may also communicate directly with each other via direct wireless link 110. Additionally, two STA 104 may communicate via direct communication link 110, regardless of whether the two STA 104 are associated with the same AP 102 and served by the same AP. In such an ad hoc system, one or more STA 104 may assume the role played by AP 102 in the BSS. Such STA 104 may be referred to as a group owner (GO) and may coordinate the transmission within the ad hoc network. Examples of direct wireless link 110 include a Wi-Fi Direct connection, a connection established by using a Wi-Fi Tunneled Direct Link Setup (TDLS) link, and other P2P group connections.

[0050] The AP 102 and the STA 104 may function and communicate (via corresponding communication links 106) in accordance with the IEEE 802.11 family of wireless communication protocol standards, such as those defined by the IEEE 802.11-2016 specification or its amendments, including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be. These standards define WLAN radio and baseband protocols for the PHY and medium access control (MAC) layers. The AP 102 and the STA 104 send and receive wireless communications (hereinafter also referred to as "Wi-Fi communications") to and from each other in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs). The AP 102 and STA 104 in the WLAN 100 may send PPDUs on an unlicensed spectrum, which may be a portion of a spectrum that includes frequency bands traditionally used by Wi-Fi technology, such as the 2.4 GHz band, the 5 GHz band, the 60 GHz band, the 3.6 GHz band, and the 700 MHz band. Some implementations of the AP 102 and STA 104 described herein may also communicate in other frequency bands, such as the 6 GHz band, that may support both licensed and unlicensed communications. The AP 102 and STA 104 may also be configured to communicate on other frequency bands, such as shared licensed frequency bands, where multiple operators may have licenses to operate in one or more of the same or overlapping frequency bands.

[0051] Each of the frequency bands may include multiple sub-bands or frequency channels. For example, PPDUs that comply with IEEE 802.11n, 802.11ac, 802.11ax, and 802.11be standard amendments may be sent on 2.4 GHz, 5 GHz, or 6 GHz frequency bands, where each frequency band is divided into multiple 20 MHz channels. In this way, these PPDUs are sent on a physical channel with a minimum bandwidth of 20 MHz, but larger channels may be formed through channel bonding. For example, a PPDU may be sent on a physical channel with a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels together.

[0052] Each PPDU is a composite structure including a PHY preamble and a payload in the form of a PHY service data unit (PSDU). The information provided in the preamble can be used by the receiving device to decode subsequent data in the PSDU. In an instance where the PPDU is sent on a bound channel, the preamble field can be copied and sent in each of a plurality of component channels. The PHY preamble may include both a legacy part (or "legacy preamble") and a non-legacy part (or "non-legacy preamble"). Legacy preambles can be used for packet detection, automatic gain control, and channel estimation, as well as other purposes. Legacy preambles can also be generally used to maintain compatibility with legacy devices. The format, decoding, and information provided therein of the non-legacy part of the preamble are based on the specific IEEE 802.11 protocol to be used to send the payload.

[0053] Figure 2A An example protocol data unit (PDU) 200 that can be used for wireless communication between an AP 102 and one or more STAs 104 is shown. For example, the PDU 200 can be configured as a PPDU. As shown, the PDU 200 includes a PHY preamble 202 and a PHY payload 204. For example, the preamble 202 can include a legacy portion, which itself includes a legacy short training field (L-STF) 206 that can be composed of two BPSK symbols, a legacy long training field (L-LTF) 208 that can be composed of two BPSK symbols, and a legacy signal field (L-SIG) 210 that can be composed of two BPSK symbols. The legacy portion of the preamble 202 can be configured according to the IEEE 802.11a wireless communication protocol standard. The preamble 202 may also include a non-legacy portion including one or more non-legacy fields 212 that comply with, for example, an IEEE wireless communication protocol such as IEEE 802.11ac, 802.11ax, 802.11be, or a later wireless communication protocol.

[0054] L-STF 206 generally enables the receiving device to perform automatic gain control (AGC) and coarse timing and frequency estimation. L-LTF 208 generally enables the receiving device to perform fine timing and frequency estimation, and can also perform initial estimation of the wireless channel. L-SIG 210 generally enables the receiving device to determine the duration of the PDU and use the determined duration to avoid sending on the PDU. For example, L-STF 206, L-LTF 208 and L-SIG 210 can be modulated according to a binary phase shift keying (BPSK) modulation scheme. Payload 204 can be modulated according to a BPSK modulation scheme, an orthogonal BPSK (Q-BPSK) modulation scheme, an orthogonal amplitude modulation (QAM) modulation scheme, or another appropriate modulation scheme. Payload 204 may include a PSDU including a data field (DATA) 214, which in turn may carry, for example, a medium access control (MAC) protocol data unit (MPDU) or higher layer data in the form of an aggregated MPDU (A-MPDU).

[0055] Figure 2B Shows Figure 2A 2. An example L-SIG 210 in a PDU 200 of FIG. L-SIG 210 includes a data rate field 222, a reserved bit 224, a length field 226, a parity bit 228, and a tail field 230. The data rate field 222 indicates the data rate (note that the data rate indicated in the data rate field 212 may not be the actual data rate of the data carried in the payload 204). The length field 226 indicates the length of the packet, for example, in symbols or bytes. The parity bit 228 can be used to detect bit errors. The tail field 230 includes a tail bit that can be used by a receiving device to terminate the operation of a decoder (e.g., a Viterbi decoder). The receiving device can use the data rate and length indicated in the data rate field 222 and the length field 226 to determine the packet duration, for example, in microseconds (μs) or other time units.

[0056] Figure 3An example PPDU 300 is shown that can be used for communication between an AP 102 and one or more STAs 104. As described above, each PPDU 300 includes a PHY preamble 302 and a PSDU 304. Each PSDU 304 may represent (or "carry") one or more MAC protocol data units (MPDUs) 316. For example, each PSDU 304 may carry an aggregate MPDU (A-MPDU) 306 that includes an aggregation of multiple A-MPDU subframes 308. Each A-MPDU subframe 306 may include an MPDU frame 310 that includes a MAC delimiter 312 and a MAC header 314 preceding an accompanying MPDU 316 that includes a data portion ("payload" or "frame body") of the MPDU frame 310. Each MPDU frame 310 may also include a frame check sequence (FCS) field 318 for error detection (e.g., the FCS field may include a cyclic redundancy check (CRC)) and padding bits 320. The MPDU 316 may carry one or more MAC service data units (MSDUs) 326. For example, the MPDU 316 may carry an aggregate MSDU (A-MSDU) 322 that includes multiple A-MSDU subframes 324. Each A-MSDU subframe 324 includes a corresponding MSDU 330 preceded by a subframe header 328 and, in some cases, followed by padding bits 332.

[0057] Referring back to the MPDU frame 310, the MAC delimiter 312 may be used as a marker for the start of an associated MPDU 316 and indicates the length of the associated MPDU 316. The MAC header 314 may include a plurality of fields containing information defining or indicating characteristics or attributes of the data encapsulated within the frame body 316. The MAC header 314 includes a duration field indicating a duration from the end of the PPDU to at least the end of an acknowledgement (ACK) or block ACK (BA) to be sent by the receiving wireless communication device for the PPDU. The use of the duration field is used to reserve the wireless medium for the indicated duration and enable the receiving device to establish its network allocation vector (NAV). The MAC header 314 also includes one or more fields indicating the address of the data encapsulated 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 also include a frame control field containing control information. The frame control field may specify a frame type, such as a data frame, a control frame, or a management frame.

[0058] Figure 4 4 shows a block diagram of an example wireless communication device 400. In some implementations, the wireless communication device 400 may be a STA (such as a reference Figure 1In some implementations, the wireless communication device 400 may be an example of a device in an AP (such as a STA in the STA 104 described above). Figure 1 The wireless communication device 400 is an example of a device in the described AP 102. The wireless communication device 400 is capable of sending (or outputting for sending) and receiving wireless communications (e.g., in the form of wireless packets). For example, the wireless communication device can be configured to: send and receive packets in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs) and medium access control (MAC) protocol data units (MPDUs) that comply with IEEE 802.11 wireless communication protocol standards (such as the standards defined by the IEEE 802.11-2016 specification or its amendments, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be).

[0059] The wireless communication device 400 may be or may include a chip, system on chip (SoC), chipset, package, or device including one or more modems 402 (e.g., Wi-Fi (IEEE 802.11 compatible) modems). In some implementations, one or more modems 402 (collectively, “modems 402”) additionally include a WWAN modem (e.g., a 3GPP 4G LTE or 5G compatible modem). In some implementations, the wireless communication device 400 also includes one or more radio components 404 (collectively, “radio components 404”). In some implementations, the wireless communication device 406 also includes one or more processors, processing blocks, or processing elements 406 (collectively, “processors 406”) and one or more memory blocks or elements 408 (collectively, “memory 408”).

[0060] Modem 402 may include intelligent hardware blocks or devices, such as, for example, application specific integrated circuits (ASICs) and other possibilities. Modem 402 is generally configured to implement the PHY layer. For example, modem 402 is configured to modulate packets and output the modulated packets to radio 404 for transmission over a wireless medium. Similarly, modem 402 is configured to obtain modulated packets received by radio 404 and demodulate these packets to provide demodulated packets. In addition to the modulator and demodulator, modem 402 may also include digital signal processing (DSP) circuits, automatic gain control (AGC), decoders, decoders, multiplexers, and demultiplexers. For example, when in transmit mode, data obtained from processor 406 is provided to a decoder, which encodes the data to provide encoded bits. The encoded bits are then mapped to points in the modulation constellation (using the selected MCS) to provide modulated symbols. The modulated symbols can then be mapped to a number N SS spatial streams or the number N STS The modulated symbols in the corresponding spatial stream or space-time stream may then be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and then provided to the DSP circuit for Tx windowing and filtering. The digital signal may then be provided to a digital-to-analog converter (DAC). The resulting analog signal may then be provided to an upconverter and ultimately to the radio component 404. In a specific implementation involving beamforming, the modulated symbols in the corresponding spatial stream may be pre-coded via a steering matrix before being provided to the IFFT block.

[0061] When in receive mode, a digital signal received from the radio component 404 is provided to a DSP circuit configured to acquire the received signal, for example, by detecting the presence of a signal and estimating initial timing and frequency offset. The DSP circuit is further configured to digitally condition the digital signal, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting I / Q imbalance), and applying digital gain to ultimately obtain a narrowband signal. The output of the DSP circuit may then be fed to an AGC configured to use information extracted from the digital signal (e.g., in one or more received training fields) to determine an appropriate gain. The output of the DSP circuit is also coupled to a demodulator configured to extract the modulated symbols from the signal and, for example, calculate a log-likelihood ratio (LLR) for each bit position of each subcarrier in each spatial stream. The demodulator is coupled to a decoder, which may be configured to process the LLRs to provide decoded bits. The decoded bits from all spatial streams are then fed to a demultiplexer for demultiplexing. The demultiplexed bits may then be descrambled and provided to the MAC layer (processor 406) for processing, evaluation, or interpretation.

[0062] The radio 404 typically includes at least one radio frequency (RF) transmitter (or "transmitter chain") and at least one RF receiver (or "receiver chain"), which may be combined into one or more transceivers. For example, the RF transmitter and receiver may include various DSP circuits, each of which includes at least one power amplifier (PA) and at least one low noise amplifier (LNA). The RF transmitter and receiver may in turn be coupled to one or more antennas. For example, in some implementations, the wireless communication device 400 may include or be coupled to multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain). The symbols output from the modem 402 are provided to the radio 404, which then transmits the symbols via the coupled antennas. Similarly, the symbols received via the antennas are obtained by the radio 404, which then provides the symbols to the modem 402.

[0063] The processor 406 may include an intelligent hardware block or device designed to perform the functions described herein, such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD) (such as a field programmable gate array (FPGA)), discrete gate or transistor logic, discrete hardware components, or any combination thereof. The processor 406 processes information received through the radio component 404 and the modem 402, and processes information to be output by the modem 402 and the radio component 404 to be sent through the wireless medium. For example, the processor 406 may implement a control plane and a MAC layer, which is configured to perform various operations related to the generation and transmission of MPDUs, frames, or packets. The MAC layer is configured to perform or facilitate the coding and decoding of frames, spatial multiplexing, space-time block coding (STBC), beamforming, and OFDMA resource allocation, as well as other operations or techniques. In some specific implementations, the processor 406 may generally control the modem 402 to cause the modem to perform the various operations described above.

[0064] The memory 408 may include a tangible storage medium, such as a random access memory (RAM) or a read-only memory (ROM) or a combination thereof. The memory 408 may also store non-transitory processor-executable or computer-executable software (SW) code containing instructions that, when executed by the processor 406, cause the processor to perform various operations for wireless communication described herein, including generation, transmission, reception, and interpretation of MPDUs, frames, or packets. For example, various functions of the components disclosed herein or various blocks or steps of the methods, operations, processes, or algorithms disclosed herein may be implemented as one or more modules of one or more computer programs.

[0065] Figure 5A 5 shows a block diagram of an example AP 502. For example, AP 502 may be a reference Figure 1 The AP 102 is described as an example implementation. The AP 502 includes a wireless communication device (WCD) 510 (although the AP 502 itself may also be generally referred to as a wireless communication device, as used herein). For example, the wireless communication device 510 may be a wireless communication device. Figure 4 The example implementation of the wireless communication device 400 described. The AP 502 also includes a plurality of antennas 520 coupled to the wireless communication device 510 to send and receive wireless communications. In some implementations, the AP 502 additionally includes an application processor 530 coupled to the wireless communication device 510 and a memory 540 coupled to the application processor 530. The AP 502 also includes at least one external network interface 550 that enables the AP 502 to communicate with a core network or a backhaul network to obtain access to an external network including the Internet. For example, the external network interface 550 may include one or both of a wired (e.g., Ethernet) network interface and a wireless network interface (such as a WWAN interface). Components of the aforementioned components may communicate directly with other components of the components or indirectly through at least one bus. The AP 502 also includes a housing that contains the wireless communication device 510, the application processor 530, the memory 540, and at least portions of the antennas 520 and the external network interface 550.

[0066] Figure 5B 5 shows a block diagram of an example STA 504. For example, STA 504 may be a reference Figure 1 The example implementation of STA 104 is described. STA 504 includes a wireless communication device 515 (although STA 504 itself may also be generally referred to as a wireless communication device as used herein). For example, wireless communication device 515 may be a reference Figure 4An example implementation of the wireless communication device 400 described. The STA 504 also includes one or more antennas 525 coupled to the wireless communication device 515 to send and receive wireless communications. The STA 504 additionally includes an application processor 535 coupled to the wireless communication device 515 and a memory 545 coupled to the application processor 535. In some implementations, the STA 504 also includes a user interface (UI) 555 (such as a touch screen or keyboard) and a display 565, which can be integrated with the UI 555 to form a touch screen display. In some implementations, the STA 504 may also include one or more sensors 575, such as, for example, one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors. Components in the aforementioned components may communicate directly with other components in the components or indirectly through at least one bus. The STA 504 also includes a housing that encloses the wireless communication device 515, the application processor 535, the memory 545, and at least portions of the antenna 525, the UI 555, and the display 565.

[0067] As described above, new WLAN communication protocols are being developed to implement enhanced features for wireless communications on carrier frequencies above 7 GHz (such as in the 60 GHz or 45 GHz bands). However, wireless communications on higher carrier frequencies may suffer from greater phase noise and path loss than wireless communications on lower frequency bands. Aspects of the present disclosure recognize that analog beamforming (using a large number of antenna elements) can mitigate the effects of path loss and achieve a greater wireless communication range on carrier frequencies above 7 GHz. Analog beamforming is a wireless communication technique by which a transmitting device and a receiving device can adjust the gain and phase of their transmit (TX) antenna elements and receive (RX) antenna elements to achieve directionality in wireless communications. For example, a transmitting device may tune a set of TX antennas to focus the energy of a transmitted signal in a particular direction (referred to as "TX beamforming"). Similarly, a receiving device may tune a set of RX antennas to focus the energy of a received signal in a particular direction (referred to as "RX beamforming"). When TX beamforming is used in combination with RX beamforming, optimal beamforming gain may be achieved (such as optimal beamforming gain may be required to overcome path loss in the 60 GHz band). The process by which the transmitting and receiving devices tune their antennas for beamforming is referred to as a "beamforming training" operation.

[0068] Existing versions of the IEEE 802.11 standard define a BSS discovery protocol for carrier frequencies below 7 GHz (also referred to as the "below 7 GHz" band), whereby an AP announces its BSS in a management frame (such as a beacon or a probe response) sent omnidirectionally. Any STA within the coverage area of ​​the AP may receive such a management frame and request to associate with the BSS. As described above, omnidirectional communications suffer from significant path loss at carrier frequencies above 7 GHz. Although beamforming can help offset the path loss associated with wireless communications at carrier frequencies above 7 GHz, the directionality of the beamformed signals (or "beams") presents challenges to BSS discovery and association. For example, beamforming gain can only be achieved when the AP sends a beam in the direction of a particular STA (or in a direction associated with a desired link budget). However, prior to discovery, the AP typically does not know the direction of the STA. Therefore, a new mode of BSS discovery (and association) is needed to support wireless communications at carrier frequencies above 7 GHz.

[0069] Various aspects generally relate to increasing carrier frequencies for wireless communications in WLANs, and more specifically, to BSS discovery and association techniques that support wireless communications at carrier frequencies above 7 GHz. In some aspects, an AP may utilize multiple wireless communication links to facilitate various management and control functions for directional communications. More specifically, an AP may communicate using beamforming on a wireless communication link operating at a carrier frequency above 7 GHz (also referred to as a "directional link"), while offloading the BSS discovery and association procedures required to support such communications to a wireless communication link operating at a carrier frequency below 7 GHz (also referred to as an "anchor link"). In some implementations, an AP may perform a beamforming training operation with a STA over the directional link while associating with the STA over the anchor link. In such implementations, the AP may communicate with the STA over the directional link using a beam derived from the beamforming training operation. In some aspects, the AP may further send a trigger frame over the anchor link that signals the start of the beamforming training operation and various control parameters associated with the beamforming training operation. In some implementations, the trigger frame may synchronize wireless communications on the anchor link with wireless communications on the directional link. For example, a trigger frame may provide a timing or frequency reference for wireless communications over a directional link.

[0070] Specific implementations of the subject matter described in the present disclosure may be implemented to achieve one or more of the following potential advantages. By utilizing a directional link for data communication (operating at a carrier frequency higher than 7 GHz) and an anchor link associated with the directional link for management and control functions (operating at a carrier frequency lower than 7 GHz), various aspects of the present disclosure may utilize existing WLAN communication protocols and hardware to support wireless communications on carrier frequencies higher than 7 GHz. As described above, existing BSS discovery and association operations may be performed using omnidirectional communications on carrier frequencies lower than 7 GHz. However, directional communications may benefit from enhanced features (such as wider bandwidth or higher data rates) on carrier frequencies higher than 7 GHz. By offloading the BSS discovery and association operations required to support wireless communications on a directional link to an anchor link, an AP may achieve the benefits of directional communications at a higher carrier frequency and omnidirectional communications for BSS discovery and association. By synchronizing wireless communications on an anchor link with wireless communications on a directional link, an AP may further reduce the overhead and delay associated with communicating on a directional link.

[0071] Figure 6 An example communication environment 600 including an AP 610 and a STA 620 according to some implementations is shown. In some implementations, the AP 610 can be Figure 1 and Figure 5A In some implementations, the STA 620 may be an example of either of the APs 102 or 502. Figure 1 and Figure 5B An example of either STA 104 or 504. Figure 6 In the example of FIG. 6 , AP 610 is associated with a BSS that supports wireless communications at carrier frequencies above 7 GHz, such as in the 60 GHz band.

[0072] In some implementations, the AP 610 may use beamforming to communicate over greater distances and mitigate the effects of path loss at carrier frequencies above 7 GHz. For example, the AP 610 may send packets or PPDUs via multiple antenna sectors T1-T7 (also referred to as "TX sectors") that are configured or tuned for TX beamforming. The antenna elements associated with each TX sector are weighted so that the energy radiated by each antenna element combines along a specific beam direction. Therefore, each of the TX sectors T1-T7 can be tuned to a corresponding TX beam direction. For simplicity, the AP 610 is shown as including 7 TX sectors T1-T7. However, in actual implementations, the AP 610 may include multiple TX sectors T1-T7. Figure 6 Fewer or more TX sectors than those depicted in .

[0073] In some implementations, STA 620 may also use beamforming to communicate on carrier frequencies above 7 GHz. For example, STA 620 may receive packets or PPDUs via multiple antenna sectors R1-R7 (also referred to as "RX sectors") configured or tuned for RX beamforming. The antenna elements associated with each RX sector are weighted so that the energy received by each antenna element is combined along a specific beam direction. Therefore, each of the RX sectors R1-R7 may be tuned to a corresponding RX beam direction. For simplicity, STA 620 is shown as including 7 RX sectors R1-R7. However, in actual implementations, STA 620 may include multiple RX sectors R1-R7. Figure 6 Fewer or more RX sectors than those depicted in .

[0074] In some aspects, the AP 610 may perform a beamforming training operation with the STA 620 to determine TX and RX beam directions that optimize beamforming gains for wireless communications between the AP 610 and the STA 620. For example, the AP 610 may train its TX antenna for TX beamforming by sending a respective beamforming training (BFT) packet via each of the TX sectors T1-T7 and receiving feedback from the STA 620 indicating the TX sector associated with the highest TX beamforming gain. In addition, the STA 620 may train its RX antenna for RX beamforming by listening to a respective BFT packet from the AP 610 via each of the RX sectors R1-R7 and determining the RX sector associated with the highest RX beamforming gain based on the received BFT packet. In some implementations, the AP 610 may further train its RX antenna (not shown for simplicity) for RX beamforming, and the STA 620 may further train its TX antenna (not shown for simplicity) for TX beamforming.

[0075] like Figure 6As shown, the AP 610 and the STA 620 may achieve optimized beamforming gains for beams transmitted via TX sector T1 (of the AP 610) and beams received via RX sector R7 (of the STA 620). In contrast, beams transmitted by the AP 610 in other TX beam directions (such as via any of TX sectors T2-T7) may fail to reach the STA 620. Therefore, the AP 610 may not be able to effectively communicate with the STA 620 at carrier frequencies above 7 GHz before performing beamforming training operations. For example, without knowing the direction of the STA 620, the AP 610 may need to transmit a beam in each of its TX beam directions so that at least one of the beams reaches the STA 620. Aspects of the present disclosure recognize that some management or control frames (such as for BSS discovery) are transmitted without knowing the presence or direction of a receiving device (such as an AP or STA). However, repeatedly sending the same management or control frame via each of TX sectors T1 - T7 consumes significant overhead and may result in inefficient use of the wireless medium.

[0076] Aspects of the present disclosure further recognize that some wireless communication devices (including APs and STAs) have multi-link operation (MLO) capabilities. Devices with MLO capabilities may be referred to as multi-link devices (MLDs). For example, an AP MLD may include multiple APs, each AP being configured to communicate with a non-AP MLD (also referred to as a "STA MLD") on a corresponding communication link. Similarly, a non-AP MLD may include multiple STAs, each STA being configured to communicate with the AP MLD on a corresponding communication link in the communication link. In some specific implementations, the AP 610 and the STA 620 may utilize multiple wireless communication links to support wireless communication at carrier frequencies above 7 GHz. More specifically, the AP 610 and the STA 620 may perform at least some management and control functions (such as BSS discovery or association) via omnidirectional communication on a wireless communication link operating at a carrier frequency below 7 GHz, and may communicate via directional beams on a wireless communication link operating at a carrier frequency above 7 GHz.

[0077] Figure 7 An example communication system 700 including an AP MLD 710 and a non-AP MLD 720 according to some implementations is shown. In some implementations, the AP MLD 710 may be a Figure 1 , Figure 5A and Figure 6 In some implementations, the non-AP MLD 720 may be an example of any of the APs 102, 502, or 610. Figure 1 , Figure 5B and Figure 6 An example of any of STA 104, 504 or 620.

[0078] AP MLD 710 includes a plurality of APs 712 and 714 associated with (or operating on) communication links 702 and 704, respectively. Figure 7 In the example of FIG. 7 , the AP MLD 710 is shown as including two APs. However, in some implementations, the AP MLD 710 may include Figure 7 . In some aspects, APs 712 and 714 may share a common association context (via AP MLD 710). APs 712 and 714 may also establish their respective communication links 702 and 704 on different frequency bands. In some implementations, AP 712 may operate at a carrier frequency below 7 GHz (such as in any of the 2.4 GHz, 5 GHz, or 6 GHz bands), and AP 714 may operate at a carrier frequency above 7 GHz (such as in the 60 GHz or 45 GHz bands).

[0079] The non-AP MLD 720 includes a plurality of STAs 722 and 724 that can be configured to communicate on communication links 702 and 704, respectively. In some implementations, the STA 722 can operate at a carrier frequency below 7 GHz (such as in any of the 2.4 GHz, 5 GHz, or 6 GHz bands), and the STA 724 can operate at a carrier frequency above 7 GHz (such as in the 60 GHz or 45 GHz bands). Figure 7 In the example of FIG. 7 , the non-AP MLD 720 is shown as including 2 STAs. However, in some implementations, the non-AP MLD 720 may include Figure 7 The present version of the IEEE 802.11 standard defines several modes in which the non-AP MLD can operate. The various operating modes depend on the number of radio devices associated with the non-AP MLD and the ability of the non-AP MLD to communicate (such as by sending or receiving) concurrently on multiple communication links.

[0080] In some implementations, the non-AP MLD 720 may include a single radio component or may otherwise be capable of communicating on only one link at a time. In such implementations, the non-AP MLD 720 may operate in a multi-link single radio (MLSR) mode or an enhanced MLSR (eMLSR) mode. A non-AP MLD operating in the eMLSR mode may concurrently listen to packets of a particular type (such as a buffer status report poll (BSRP) frame or a multi-user request to transmit (MU-RTS) frame) on multiple links, but may only transmit or receive on one of the communication links at any given time. For example, STAs 722 and 724 may concurrently listen to their respective links 702 and 704 during the listening interval. However, if either STA 722 or STA 724 detects a BSRP frame on their respective links, the non-AP MLD 720 then tunes all of its antennas to the link on which the BSRP frame was detected. In contrast, a non-AP MLD operating in the MLSR mode may only listen to one communication link at any given time and may only transmit or receive on one communication link. For example, either STA 722 or 724 must be in a power save mode any time the other STA is active.

[0081] In some other implementations, the non-AP MLD 720 may include multiple radio components and may be capable of concurrent communication on each of the links 702 and 704. In such implementations, the non-AP MLD 720 may operate in a multi-link multi-radio (MLMR) simultaneous transmit and receive (STR) mode or a multi-link multi-radio non-STR (NSTR) mode. A non-AP MLD operating in the MLMR STR mode may transmit and receive simultaneously on multiple links. For example, STA 722 may transmit or receive on link 702 while STA 724 concurrently transmits or receives on link 704. More specifically, such communications may be asynchronous. In other words, STA 722 may transmit on link 702 while STA 724 receives on link 704. In contrast, a non-AP MLD operating in the MLMR NSTR mode may transmit and receive simultaneously on multiple links only if such communications are synchronous. For example, STA 722 and 724 may transmit concurrently on links 702 and 704, and may also receive concurrently on links 702 and 704. However, STA 722 may not transmit on link 702 while STA 724 is receiving on link 704.

[0082] Further, in some implementations, the non-AP MLD may include multiple radio components, but may be capable of concurrent communication only on a subset of links. In such implementations, the non-AP MLD 720 may operate in an enhanced MLMR (eMLMR) mode or a hybrid eMLSR mode. A non-AP MLD operating in the eMLMR mode only supports MLMRSTR operations between some link pairs. For example, STAs 722 and 724 may communicate concurrently on their respective links 502 and 504 according to the MLMR STR operation mode, while other STA pairs associated with the non-AP MLD 720 (not shown for simplicity) may not concurrently transmit or receive on their respective links (referred to herein as "eMLMR links"). Therefore, such other STAs may "pool" their antennas so that each of the STAs may utilize the antennas of other STAs when transmitting or receiving on one of the eMLMR links. On the other hand, a non-AP MLD operating in the hybrid eMLSR mode supports MLMRSTR operations between some link pairs and eMLSR operations between some other link pairs.

[0083] In some aspects, the AP MLD 710 and the non-AP MLD 720 may perform various management and control functions (such as BSS discovery or association) on the link 702, and may exchange directional communications on the link 702 based on the management and control functions performed on the link 704. As such, the link 704 may be a directional link, and the link 702 may be an anchor link associated with the directional link. In some implementations, the AP MLD 710 may advertise its BSS in a management frame (such as a beacon or a probe response) sent omnidirectionally on the anchor link 702. The AP MLD 710 may further associate with the non-AP MLD 720 via the anchor link 702 based on the BSS information carried in the beacon or the probe response. In some implementations, the AP MLD 710 may communicate with the non-AP MLD 720 on the directional link 704 based on the association context established on the anchor link 702. More specifically, the AP MLD 710 and the non-AP MLD 720 may use beamforming techniques (such as reference beamforming techniques). Figure 6 described) communicate over a directional link 704.

[0084] Figure 8 8 shows a sequence diagram 800 depicting an example multi-link communication between an AP 810 and a STA 820 according to some implementations. In some implementations, the AP 810 and the STA 820 may be Figure 7802 and 804. Figure 7 , communication links 802 and 804 may be examples of communication links 702 and 704, respectively. As such, link 802 may be an anchor link operating at a carrier frequency below 7 GHz, and link 804 may be a directional link operating at a carrier frequency above 7 GHz.

[0085] exist Figure 8 In the example of , AP 810 and STA 820 are initially in a non-associated state. Therefore, AP 810 and STA 820 may perform BSS discovery over anchor link 802. For example, the AP may send a management frame (such as a beacon or a probe response) carrying BSS information announcing its BSS over anchor link 802. Such management frames may be sent omnidirectionally so that any STA within the coverage area of ​​AP 810 may discover the BSS. Upon discovering the BSS, STA 820 may request to associate with AP 810. Therefore, AP 810 and STA 820 may perform an association operation over anchor link 802. For example, STA 820 may first initiate a low-level authentication exchange with AP 810 over anchor link 802. After authentication, STA 820 may send an association request to AP 810 over anchor link 802. AP 810 may complete the authentication process by sending an authentication response back to STA 820 over anchor link 802.

[0086] Once associated, AP 810 may communicate with STA 820 via directional link 804. In this way, wireless communications on directional link 804 (such as for data transmission) are effectively coupled to wireless communications on anchor link 802 (such as for BSS discovery and association). In some implementations, STA 820 (and AP 810) may use reference Figure 7 The AP 810 and the STA 820 may use any of the techniques described to switch between the anchor link 802 and the directional link 804. In some aspects, the AP 810 and the STA 820 may use beamforming techniques when communicating on the directional link 804, for example, to mitigate the effects of path loss at carrier frequencies above 7 GHz. Figure 6 As described, AP 810 may perform beamforming training operations with STA 820 to determine TX and RX beam directions that optimize beamforming gain.

[0087] In some implementations, the AP 810 may initiate a beamforming training operation by sending a corresponding BFT packet on the directional link 804 via each of its TX sectors, and the STA 820 may provide feedback to the AP 810 in response to receiving one or more of the BFT packets. For example, the feedback may indicate which of the BFT packets sent by the AP 810 (or the TX sector) is associated with the highest signal power. In some other implementations, the STA 820 may initiate a beamforming training operation by sending a corresponding BFT packet on the directional link 804 via each of its TX sectors, and the AP 810 may provide feedback to the STA 820 in response to receiving one or more of the BFT packets. For example, the feedback may indicate which of the BFT packets sent by the STA 820 (or the TX sector) is associated with the highest signal power. A device that initiates a beamforming training operation is referred to as a "beamforming initiator." In contrast, a device that responds (or provides feedback) to a beamformer initiator is referred to as a "beamformer responder."

[0088] As a result of the beamforming training operation, the beamforming initiator selects a TX beam direction to be used for directional communication with the beamforming responder, and the beamforming responder selects an RX beam direction to be used for directional communication with the beamforming initiator. In some implementations, the beamforming initiator may also select an RX beam direction to be used for directional communication with the beamforming responder, and the beamforming responder may also select a TX beam direction to be used for directional communication with the beamforming initiator. Thus, the AP 810 may communicate with the STA 820 over a directional link using beams associated with the TX and RX directions determined as a result of the beamforming training operation. In some implementations, the AP 810 may further refine its TX or RX beam direction based on real-time communication with the STA 820. In some implementations, the STA 820 may further refine its TX or RX beam direction based on real-time communication with the AP 810.

[0089] Fig. 9 A timing diagram 900 depicting example wireless communications between an AP and a STA over a directional link according to some implementations is shown. In some implementations, the APs may be Figure 6 and Figure 8 AP 610 or 810, or Figure 7 In some implementations, the STAs may be respectively Figure 6 and Figure 8 STA 620 or 820, or Figure 7An example of any of the non-AP MLDs 720. For example, refer to Figure 8 , a directional link may be an example of directional link 804. Fig. 9 In the example, the AP is associated with the STA. For example, at time t 0 Previously, the AP may perform an association operation with the STA through an anchor link (not shown for simplicity).

[0090] At time t 0 and t 2 During the period between the AP and STA, the AP and STA perform beamforming training operations on the directional link. Fig. 9 In the example, the AP is at time t 0 The beamforming training operation is initiated by sending multiple (N) BFT packets in various TX beam directions. More specifically, at least one BFT packet may be sent by each TX sector associated with the AP (such as Figure 6 In some implementations, each of the BFT packets may carry beam management information that may be used to train the TX or RX sector of the AP. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of BFT packets (N), number of remaining BFT packets to be sent (M), sector identifier (ID), antenna ID, or number of RX antennas or sectors associated with the AP, among other examples. However, because the AP is already associated with the STA via the anchor link, the BFT packets do not need to carry additional BSS information (such as for BSS discovery).

[0091] The STA receives one or more BFT packets in the BFT packet and compares the signal power of the received BFT packets. 1 , the STA provides feedback (FB) to the AP indicating which of the BFT packets has the highest received signal power. For example, the feedback may include the best sector ID, the best antenna ID, or a signal-to-noise ratio (SNR) report, among other examples. Although not shown for simplicity, the STA may further train its RX antenna for RX beamforming (such as reference Figure 6 In some implementations, a STA may train its RX antenna based on a BFT packet sent by an AP (at time t 0 to 1 In some other implementations, the STA may perform an additional packet exchange with the AP (at time t 1 and t 2In some aspects, the AP may train its RX antenna for RX beamforming based on the additional packet exchange. In some other aspects, the STA may train its TX antenna for TX beamforming based on the additional packet exchange.

[0092] At time t 2 , the AP sends service period (SP) scheduling information, which allocates SPs for directional communication with STAs. Fig. 9 In the example, SP is scheduled to start from time t 3 to 5 occurs. In some implementations, the AP may unilaterally assign a STA to a specific SP. In some other implementations, a STA may request to be assigned to a specific SP. In such implementations, the AP and the STA may negotiate a SP schedule for subsequent wireless communications on the directional link. At time t 3 , the AP initiates TX data transmission to the STA using the beam determined based on the beamforming training operation. For example, the AP may initiate TX data transmission to the STA via 1 In some aspects, the STA may receive TX data via the best RX sector determined by the beamforming training operation. At time t 4 , the STA sends an acknowledgement frame (ACK) or a block ACK to the AP to confirm receipt of the TX data.

[0093] like Fig. 9 As shown, offloading the BSS discovery and association functions to the anchor link significantly reduces the overhead and delay associated with communications on the directional link. For example, the AP does not need to send beacons or probe response frames announcing its BSS in each beam direction on the directional link. Similarly, the STA does not need to send probe request frames for scanning BSSs in each beam direction on the directional link. Instead, when associating over the anchor link, the AP and STA can immediately perform beamforming training operations on the directional link and continue data communications. Aspects of the present disclosure recognize that by offloading at least some of the signaling overhead associated with the beamforming training operations to the anchor link, the overhead and delay associated with communications on the directional link can be further reduced.

[0094] Fig.10 A timing diagram 1000 depicting example wireless communications between an AP and a STA via an anchor link (AL) and a directional link (DL) is shown according to some implementations. In some implementations, the AP may be Figure 6 and Figure 8 AP 610 or 810, or Figure 7is an example of any one of the AP MLDs 710. In some implementations, the STAs may be Figure 6 and Figure 8 STA 620 or 820, or Figure 7 An example of any of the non-AP MLDs 720. For example, refer to Figure 7 and Figure 8 , the anchor link may be an example of either anchor link 702 or 802, and the directional link may be an example of either directional link 704 or 804. Fig.10 In the example, the AP is associated with the STA. Therefore, at time t 0 Previously, the AP could perform an association operation with the STA through an anchor link.

[0095] At time t 0 , the AP (as the beamforming initiator) sends a trigger frame on the anchor link, which signals the start of a beamforming training operation to be performed on the directional link. In some implementations, the trigger frame may carry beam management setting information indicating one or more control parameters associated with the beamforming training operation. Fig.10 In the example of , the beamforming training operation is scheduled to start from time t 1 to 3 In some aspects, the trigger frame may provide a timing reference for wireless communication on the directional link. For example, the STA knows that it will perform beamforming training operations on the directional link within a threshold duration of receiving the trigger frame on the anchor link. In this way, the STA may operate in a power saving mode on the directional link until it receives the trigger frame from the AP.

[0096] In some implementations, the beam management setup information may include a subset of the beam management information that would otherwise be included in a BFT packet sent during a beamforming training operation (such as reference Fig. 9 More specifically, the beam management setting information may include any information that is common to each of the BFT groups. Example beam management setting information may include, among other things, the total number of BFT groups to be sent by the AP (N), the number of TX and RX antennas or sectors associated with the AP, or the total number of BFT groups allowed to be sent by the STA (K).

[0097] At time t 1 , the AP initiates a beamforming training operation by sending N BFT packets in each TX beam direction on a directional link. More specifically, at least one BFT packet may be sent by each TX sector associated with the AP (such as Figure 6In some implementations, each of the BFT packets may carry beam management information that may 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 been signaled via a trigger frame. Example beam management information may include PPDU type, training direction (TX or RX), beam tracking request, number of remaining BFT packets to send (M), sector ID, or antenna ID, among other examples. Thus, sending a trigger frame on the anchor link further reduces the overhead associated with each of the BFT packets (compared to Fig. 9 compared to BFT grouping).

[0098] The STA receives one or more BFT packets in the BFT packet and compares the signal power of the received BFT packets. 2 , the STA provides feedback (FB) on the directional link indicating which of the BFT packets has the highest received signal power. For example, the feedback may include the best sector ID, the best antenna ID, or an SNR report, among other examples. In some implementations, the STA may further train its RX antenna for RX beamforming (at time t 1 to 2 In some other implementations, the STA may perform an additional packet exchange with the AP (at time t 2 and t 3 In some aspects, the AP may train its RX antenna for RX beamforming based on the additional packet exchange. In some other aspects, the STA may train its TX antenna for TX beamforming based on the additional packet exchange.

[0099] At time t 3 , the AP sends SP scheduling information for allocating SPs for directional communication with STAs on the directional link. Fig.10 In the example, SP is scheduled to start from time t 4 to 6 occurs. In some implementations, the AP may unilaterally assign a STA to a specific SP. In some other implementations, a STA may request to be assigned to a specific SP. In such implementations, the AP and the STA may negotiate a SP schedule for subsequent wireless communications on the directional link. At time t 4 , the AP initiates TX data transmission on the directional link using the beam determined based on the beamforming training operation. For example, the AP may initiate TX data transmission on the directional link via 2 In some aspects, the STA may receive TX data via the best RX sector determined by the beamforming training operation. At time t5 , the STA sends an ACK or block ACK on the directional link to confirm the receipt of the TX data.

[0100] As reference Fig.10 As described, on the anchor link (at time t 0 ) may provide a timing reference for communication on the 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 (LO) of the AP may drive the carrier frequency used for wireless communication by the AP on each of the anchor link and the directional link, and the same LO of the STA may drive the carrier frequency used for wireless communication by the STA on each of the anchor link and the directional link. Therefore, the carrier frequency offset (CFO) on the anchor link is associated with the CFO on the directional link. For example, the STA may determine the CFO based on the CFO at time t 0 The received trigger frame may be used to estimate the CFO on the anchor link, and the CFO estimate associated with the anchor link may be used to narrow the range of possible CFO estimates for the directional link (such as to within a few kilohertz).

[0101] Aspects of the present disclosure recognize that wireless communications at higher carrier frequencies may suffer from greater phase noise than wireless communications at lower frequency bands. For example, increasing the carrier frequency from 5.8 GHz to 60 GHz results in a 10-fold increase in phase noise. Aspects of the present disclosure further recognize that phase noise may be mitigated by increasing the subcarrier spacing (SCS) between modulated subcarriers. As shown in reference Figure 2A As described, the existing WLAN packet format includes an L-STF that is modulated on every 4th subcarrier across a given bandwidth to support CFO estimates that are up to 2 subcarriers apart. In addition, the LO implemented by the existing WLAN transmitter and receiver is required to be accurate up to ±20ppm. As such, the existing WLAN architecture can support CFOs up to ±40ppm (between the transmitter and receiver), which is equivalent to ±2.4MHz in the 60GHz band and ±1.8MHz in the 45GHz band. In order to support CFOs up to ±2.4MHz, the SCS associated with the L-STF should be greater than or equal to 1.2MHz.

[0102] In some aspects, a wireless communication device (such as an AP or STA) may up-clock a PPDU for transmission at a carrier frequency above 7 GHz, wherein the PPDU conforms to an existing PPDU format associated with a frequency band below 7 GHz. As used herein, the term "up-clocking" refers to increasing the frequency of a clock signal used to convert the PPDU between the frequency domain and the time domain (above the frequency (f) associated with the existing PPDU format). 0 )), and the frequency of the upper clock control (fs ) and f 0 The ratio (K) of ). For example, the clock signal may be provided to a digital-to-analog converter (DAC) that samples the output of an inverse fast Fourier transform (IFFT). The IFFT transforms the multiple (N) modulated subcarriers representing the PPDU into N time domain samples. In some aspects, the clock signal frequency f s With IFFT size (N IFFT ) may result in an SCS greater than or equal to 1.2 MHz, where the SCS represents the spacing between subcarriers on which the PHY preamble (including the L-STF) of the PPDU is modulated. More specifically, the SCS as a result of the up-clocking (SCS U ) may be an SCS associated with an existing PPDU format (SCS 0 ), where SCS U =K*SCS 0 .

[0103] Fig.11 1 is a block diagram of an example TX processing chain 1100 for a wireless communication device according to some implementations. The TX processing chain 1100 is configured to process a PPDU 1101 for transmission as a radio frequency (RF) signal 1105 over a directional link. In some aspects, the PPDU 1101 may be Figure 3 In some implementations, the wireless communication devices may be respectively Figure 6 and Figure 8 AP 610 or 810, or Figure 7 An example of any of the AP MLDs 710. In some other specific implementations, the wireless communication devices may be respectively Figure 6 and Figure 8 STA 620 or 820, or Figure 7 is an example of any one of the non-AP MLDs 720. Thus, the directional links may be respectively Figure 7 and Figure 8 For simplicity, Fig.11 Only a single spatial stream of the TX processing chain 1100 is depicted. In actual implementations, the TX processing chain 1100 may include any number of spatial streams.

[0104] The TX processing chain 1100 includes a cluster mapper 1110, an orthogonal frequency division multiplexing (OFDM) modulator 1120, an RF mixer 1130, and a power amplifier (PA) 1140. The cluster mapper 1110 maps the PPDU 1101 to one or more frequency domain (FD) symbols 1102 associated with a modulation scheme. Example suitable modulation schemes include binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), and quadrature amplitude modulation (QAM). The OFDM modulator 1120 modulates the FD symbols 1102 onto a set of orthogonal subcarriers and converts the modulated subcarriers into a time-varying TX signal 1103. The RF mixer 1130 up-converts the TX signal 1103 to a carrier frequency, and the power amplifier 1140 amplifies the resulting RF signal 1105 for transmission via one or more antennas 1150. For example, the RF mixer 1130 may modulate the TX signal 1103 onto the LO signal 1104 oscillating at the carrier frequency. Fig.11 In the example of , the carrier frequency associated with the LO signal 1104 is shown to be above 7 GHz. In some specific implementations, the carrier frequency can be in the 60 GHz band. In some other specific implementations, the carrier frequency can be in the 45 GHz band.

[0105] As described above, many existing WLAN architectures are designed for wireless communications on carrier frequencies below 7 GHz (such as in 2.4 GHz, 5 GHz, or 6 GHz bands). In some aspects, existing WLAN hardware may be modified to support wireless communications on carrier frequencies above 7 GHz. For example, the TX processing chain 1100 may receive a LO signal 1104 from a local oscillator accurate to ±20 ppm. As described above, increasing the carrier frequency of the LO signal 1104 also increases the phase noise associated with the RF signal 1105. For example, operating a local oscillator at 60 GHz may result in a CFO of ±2.4 MHz between the transmitter and the receiver. According to an existing version of the IEEE 802.11 standard, the PHY preamble of the PPDU 1101 includes an L-STF with a 1x symbol duration associated with an SCS equal to 312.5 KHz, which may support CFO estimates separated by up to 2 subcarriers. As used herein, the term "1xSCS" refers to the subcarrier spacing between subcarriers to which the L-STF is mapped. Therefore, to support CFO up to ±2.4 MHz, the 1x SCS associated with the PPDU 1101 should be greater than or equal to 1.2 MHz.

[0106] Aspects of the present disclosure recognize that any SCS greater than or equal to 1.2 MHz may not be suitable for wireless communications on carrier frequencies below 7 GHz. As such, existing WLAN communication protocols for wireless communications below 7 GHz (such as IEEE 802.11be, 11ax, 11ac, and earlier amendments to the IEEE 802.11 standard) do not define a PPDU format or frequency modulation plan with an SCS greater than or equal to 1.2 MHz. In some aspects, the TX processing chain 1100 may receive a PPDU 1101 formatted for transmission on a carrier frequency below 7 GHz, and may up-clock the PPDU 1101 to a wider bandwidth suitable for transmission on a carrier frequency above 7 GHz (such as in a 60 GHz or 45 GHz band). For example, the wider bandwidth is achieved by extending the subcarriers to which the PPDU 1101 is mapped. Therefore, in some specific implementations, the TX processing chain 1100 may up-clock the PPDU 1101 so that the 1x SCS associated with the PPDU 1101 is greater than or equal to 1.2 MHz.

[0107] In some aspects, the PPDU 1101 may follow the PPDU format defined by the IEEE 802.11be (or 11ax) amendment to the IEEE 802.11 standard. For example, the PPDU 1101 may follow the 11be PPDU format associated with a 20MHz, 40MHz, or 80MHz channel bandwidth (in a frequency band below 7GHz), and may be clocked for transmission over an 80MHz, 160MHz, 320MHz, 480MHz, 640MHz, 960MHz, 1.28GHz, 1.92GHz, or 2.56GHz bandwidth wireless channel in a 60GHz or 45GHz frequency band. In some aspects, when the PPDU 1101 is sent to a receiving device that is not configured for RX beamforming (such as during a beamforming training operation), the PPDU format may be used to overcome path loss on a directional link. For example, the IEEE 802.11be amendment to the IEEE 802.11 standard defines an extended range (ER) single user (SU) PPDU format that increases the power of the PPDU to support wireless communications over a longer distance. Therefore, in some implementations, the PPDU 1101 may follow the ER SU PPDU format.

[0108] Fig. 12A Another example PPDU 1200 formatted according to the legacy PPDU format is shown. Fig. 12AIn the example of , the legacy PPDU format is an ER SU PPDU format associated with a 20 MHz channel bandwidth. The PPDU 1200 includes a PHY preamble having a first portion 1201 and a second portion 1202, followed by a data portion 1203 and a packet extension (PE) 1204. The first preamble portion 1201 includes an L-STF, an L-LTF, an L-SIG, a repetition of the L-SIG (RL-SIG), and four non-legacy signal fields (SIG1-SIG4). The second preamble portion 1202 includes a non-legacy short training field (STF) and one or more non-legacy long training fields (LTF).

[0109] The IEEE 802.11be amendment to the IEEE 802.11 standard defines each of the non-legacy signal fields SIG1–SIG4 as a universal signal field (U-SIG), and defines the remaining non-legacy fields STF and LTF as extremely high throughput (EHT) fields EHT-STF and EHT-LTF, respectively. In addition, the STF sequence associated with the L-STF is repeated (2 times) in the time domain to produce an "extended L-STF". In some specific implementations, one or more of the signal fields L-SIG, RL-SIG, or SIG1–SIG4 may be changed to carry signaling or other information specific to wireless communications on carrier frequencies above 7 GHz (such as beam management information). According to the 11be PPDU format, the data portion 1203 (and PE 1204) is mapped to each consecutive data subcarrier associated with a 256-subcarrier frequency modulation plan (which includes 234 data subcarriers and 8 pilot subcarriers). In contrast, the L-STF is mapped to every 4th data subcarrier associated with the 64-subcarrier frequency modulation plan, while the remainder of the first preamble portion 1201 is mapped to each consecutive data subcarrier associated with the 64-subcarrier frequency modulation plan. Thus, the SCS associated with the L-STF is 4 times larger than the SCS associated with the data portion 1203.

[0110] Fig. 12B According to some specific implementations, Fig. 12A 12. The PPDU 1210 includes a PHY preamble 1211 followed by a PE or training (TRN) field 1214. In some aspects, the PPDU 1210 may represent a PPDU 1200 that is clocked M times. As such, the PHY preamble 1211 and the PE or TRN field 1214 may be, respectively. Fig. 12A An example of the first preamble code part 1201 and PE 1204.

[0111] In some implementations, when the receiving device (or beamforming responder) is not configured for RX beamforming, the PPDU 1210 can be used as a BFT packet for beamforming training operations. In such implementations, the beam management information can be carried in the signal fields L-SIG, RL-SIG, or SIG1-SIG4. Thus, if Fig. 12B As shown, PPDU 1210 may not include data portion 1203 or second preamble portion 1202 of PPDU 1200. Fig. 12A As described, the SCS associated with the L-STF is 4 times greater than the SCS associated with the PE 1204. Therefore, the first preamble portion 1201 may be up-clocked by a factor of M / 4 and replicated 4 times in the frequency domain to achieve the same SCS in the L-STF as in the PE 1204. In some aspects, the up-clocking may be performed by Fig.11 The OFDM modulator 1120 may perform the OFDM modulation. For example, the OFDM modulator 1120 may clock the first preamble portion 1201 up by a factor of M / 4 and may clock the remainder of the PPDU 1200 up by a factor of M. Thus, the PE or TRN field 1214 is spread over a 20*M MHz bandwidth and the PHY preamble 1211 is replicated over four 5*M MHz sub-bands spanning the 20*M MHz bandwidth.

[0112] Fig.13 1 is a block diagram of an example AFE 1300 for a wireless communication device according to some implementations. The TX processing chain 1300 is configured to send TX signals 1301 and 1305 on a directional link and an anchor link, respectively. In some implementations, the wireless communication device may be Figure 6 and Figure 8 AP 610 or 810, or Figure 7 An example of any of the AP MLDs 710. In some other specific implementations, the wireless communication devices may be respectively Figure 6 and Figure 8 STA 620 or 820, or Figure 7 An example of any of the non-AP MLDs 720. For example, refer to Figure 7 and Figure 8 , the anchor link may be an example of either of the anchor links 702 or 802 , and the directional link may be an example of either of the directional links 704 or 804 .

[0113] AFE 1300 includes RF mixers 1310 and 1370, power amplifiers 1320 and 1380, local oscillator 1340, and frequency synthesizers 1350 and 1360. RF mixer 1310 up-converts TX signal 1301 to a carrier frequency associated with a directional link, and power amplifier 1320 amplifies the resulting RF signal 1303 for transmission via one or more antennas 1330. For example, RF mixer 1310 may modulate TX signal 1301 onto a carrier frequency (CF) signal 1302 oscillating at a desired carrier frequency. Fig.13 In the example of FIG. 1 , the carrier frequency associated with the CF signal 1302 is shown to be above 7 GHz. In some implementations, the carrier frequency may be in the 60 GHz band. In some other implementations, the carrier frequency may be in the 45 GHz band.

[0114] The RF mixer 1370 up-converts the TX signal 1305 to a carrier frequency associated with the anchor link, and the power amplifier 1380 amplifies the resulting RF signal 1307 for transmission via one or more antennas 1390. For example, the RF mixer 1370 may modulate the TX signal 1305 onto a CF signal 1306 oscillating at a desired carrier frequency. Fig.13 In the example of , the carrier frequency associated with the CF signal 1306 is shown to be below 7 GHz. In some specific implementations, the carrier frequency can be in the 2.4 GHz band. In some other specific implementations, the carrier frequency can be in the 5 GHz band. Further, in some specific implementations, the carrier frequency can be in the 6 GHz band.

[0115] exist Fig.13 , CF signals 1302 and 1306 are each derived from a LO signal 1304 generated by a local oscillator 1340. For example, LO signal 1304 may be provided as an input to frequency synthesizers 1350 and 1360, which generate CF signals 1302 and 1306, respectively, based on LO signal 1304. In this way, the anchor link and the directional link are "synchronized in frequency." Because CF signals 1302 and 1306 are driven by the same local oscillator 1340, the CFO on the directional link may be estimated within a threshold range (such as a few kilohertz) based on the estimated CFO on the anchor link. Due to the reduced pull-in range, the receiving device may estimate the CFO on the directional link within a shorter STF duration (compared to the duration required to estimate the CFO on a directional link that is not synchronized in frequency with the anchor link). Thus, TX signal 1301 may represent an STF signal that is respectively synchronized with the directional link. Fig. 12A or Fig. 12BThe PPDU 1200 or 1210 may be compared to a PPDU having a shorter L-STF duration (even in the case where the PPDU is sent to a receiving device that is not configured for RX beamforming).

[0116] As reference Fig.13 As described, synchronizing the CF signals 1302 and 1306 to the same local oscillator 1340 can reduce the overhead and delay associated with communication on the directional link. Aspects of the present disclosure recognize that by synchronizing the timing of the TX signals 1301 and 1305 to the same clock, the overhead and delay associated with communication on the directional link can be further reduced. In some aspects, the wireless communication device may include a clock (not shown for simplicity) that controls the timing of wireless communications on the directional link and the anchor link. For example, the same clock controls the time when the TX signal 1301 is sent on the directional link and the time when the TX signal 1305 is sent on the anchor link. In this way, the anchor link and the directional link are "synchronized in time."

[0117] In some aspects, the anchor link and the directional link may be synchronized in both time and frequency. In such aspects, the receiving device may calibrate the timing and frequency of the communication on the directional link based on the packets received on the anchor link. For example, the receiving device may estimate the CFO on the directional link based only on the estimated CFO on the anchor link. In some specific implementations, the sending device may send a trigger frame on the anchor link, which signals the timing of the additional packets to be sent on the directional link. In such specific implementations, the receiving device does not need to perform packet detection on the directional link to receive the additional packets. Instead, the receiving device may determine the timing and CFO associated with the additional packets based on the timing and CFO associated with the trigger frame received on the anchor link. Therefore, the additional packets sent on the directional link may carry significantly less overhead than packets otherwise sent without the timing and frequency information obtained from the anchor link.

[0118] Fig.14A A timing diagram 1400 depicting example wireless communications between an AP and a STA via an anchor link (AL) and a directional link (DL) is shown according to some implementations. In some implementations, the AP may be Figure 6 and Figure 8 AP 610 or 810, or Figure 7 is an example of any one of the AP MLDs 710. In some implementations, the STAs may be Figure 6 and Figure 8 STA 620 or 820, or Figure 7 An example of any of the non-AP MLDs 720. For example, refer to Figure 7 and Figure 8, the anchor link may be an example of either anchor link 702 or 802, and the directional link may be an example of either directional link 704 or 804. Fig.14A In the example, the AP is associated with the STA. Therefore, at time t 0 Previously, the AP could perform an association operation with the STA through an anchor link.

[0119] exist Fig.14A In the example of FIG. 1 , the directional link and the anchor link are synchronized in both time and frequency (such as reference Fig.13 In other words, the same local oscillator drives the carrier frequency used for wireless communication by the AP on each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the AP on each of the anchor link and the directional link. Similarly, the same local oscillator drives the carrier frequency used for wireless communication by the STA on each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the STA on each of the anchor link and the directional link.

[0120] At time t 0 , the AP (as the beamforming initiator) sends a trigger frame on the anchor link, which signals the start of the beamforming training operation to be performed on the directional link. Fig.14A In the example of , the beamforming training operation is scheduled to start from time t 1 to 3 occurs. 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 that would otherwise be included in the BFT packets sent during the beamforming training operation. The beam management setup information may include any information that is common to each of the BFT packets. Example beam management setup information may include, among other things, the total number of BFT packets to be sent by the AP (N), the number of TX and RX antennas or sectors associated with the AP, or the total number of BFT packets allowed to be sent by the STA (K).

[0121] In some aspects, the trigger frame may further provide a timing and frequency reference for wireless communication on the directional link. For example, the beam management setting information may include timing and frequency information indicating the timing of wireless communication on the directional link and a CFO associated with the wireless communication on the directional link. In other words, the STA knows that it will be on the directional link at time t based on the timing information included in the trigger frame or derived from receiving the trigger frame. 1Perform beamforming training operations. In addition, the STA may estimate the CFO associated with wireless communication on the directional link based on frequency information (such as L-STF) included in the trigger frame. Therefore, when a trigger frame associated with a beamforming training operation is received, the L-STF may not be present in each BFT packet sent on the directional link. Fig.14A In the example of FIG. 4 , each BFT packet in the BFT packets is depicted as a short training sequence (TS).

[0122] At time t 1 , the AP initiates a beamforming training operation by sending N training sequences in various TX beam directions over a directional link. More specifically, at least one training sequence may be sent by each TX sector associated with the AP (such as Figure 6 In some aspects, the STA may transmit based on the anchor link (at time t 0 ) received trigger frame and the timing of each training sequence (such as indicated by a timestamp) to determine the sector ID (of the AP) from which the training sequence is sent. In some other aspects, each training sequence in the training sequences may carry beam management information that explicitly signals one or more training parameters. More specifically, the beam management information may include any information that has not been signaled via a trigger frame. In some specific implementations, each training sequence in the training sequences may consist of a single LTF (such as an L-LTF) designed to indicate one or more beam management parameters (such as a sector ID). In some other specific implementations, each training sequence in the training sequences may consist of an LTF and a signal field (such as an L-SIG) to carry additional beam management information (such as a training direction, a beam tracking request, the number of remaining training sequences to be sent (M), or an antenna ID).

[0123] The STA receives one or more training sequences in the training sequence and compares the signal power of the received training sequences. 2 , the STA provides feedback (FB) on the anchor link indicating which of the training sequences has the highest received signal power. For example, the feedback may include the best sector ID, the best antenna ID, or an SNR report, among other examples. In some implementations, the STA may further train its RX antennas for RX beamforming (at time t 1 to 2 In some other implementations, the STA may perform an additional packet exchange with the AP (at time t 2 and t 3In some aspects, the AP may train its RX antenna for RX beamforming based on the additional packet exchange. In some other aspects, the STA may train its TX antenna for TX beamforming based on the additional packet exchange.

[0124] At time t 3 , the AP sends SP scheduling information on the directional link, which allocates SPs for directional communication with STAs. In some aspects, the SP scheduling information may be sent on the anchor link (such as Fig.14A Because the anchor link is synchronized with the directional link in time, the STA knows that the SP is scheduled to be on the directional link from time t 4 to 6 In some other aspects, SP scheduling information may be sent over a directional link (such as a reference Fig. 9 and Fig.10 ). In some implementations, the AP may unilaterally assign a STA to a specific SP. In some other implementations, the STA may request to be assigned to a specific SP. In such implementations, the AP and the STA may negotiate a SP schedule for subsequent wireless communications over the directional link.

[0125] At time t 4 , the AP initiates TX data transmission on the directional link using the beam determined based on the beamforming training operation. For example, the AP may initiate TX data transmission on the directional link via 2 In some aspects, the STA may receive TX data via the best RX sector determined by the beamforming training operation. At time t 5 , the STA sends an ACK or block ACK to confirm receipt of the TX data. In some implementations, the ACK or block ACK may be sent over a directional link (such as Fig.14A In some other implementations, an ACK or a block ACK may be sent on the anchor link.

[0126] Fig. 14B Another timing diagram 1410 depicting example wireless communications between an AP and a STA over an anchor link (AL) and a directional link (DL) according to some implementations is shown. In some implementations, the AP may be Figure 6 and Figure 8 AP610 or 810, or Figure 7 is an example of any one of the AP MLDs 710. In some implementations, the STAs may be Figure 6 and Figure 8 STA 620 or 820, or Figure 7An example of any of the non-AP MLDs 720. For example, refer to Figure 7 and Figure 8 , the anchor link may be an example of either anchor link 702 or 802, and the directional link may be an example of either directional link 704 or 804. Fig. 14B In the example, the AP is associated with the STA. Therefore, at time t 0 Previously, the AP could perform an association operation with the STA through an anchor link.

[0127] exist Fig. 14B In the example of FIG. 1 , the directional link and the anchor link are synchronized in both time and frequency (such as reference Fig.13 In other words, the same local oscillator drives the carrier frequency used for wireless communication by the AP on each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the AP on each of the anchor link and the directional link. Similarly, the same local oscillator drives the carrier frequency used for wireless communication by the STA on each of the anchor link and the directional link, and the same clock controls the timing of wireless communication by the STA on each of the anchor link and the directional link.

[0128] At time t 0 , the AP (as the beamforming initiator) sends a trigger frame on the anchor link, which signals the start of the beamforming training operation to be performed on the directional link. Fig. 14B In the example of , the beamforming training operation is scheduled to start from time t 1 to 3 occurs. 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 that would otherwise be included in the BFT packets sent during the beamforming training operation. The beam management setup information may include any information that is common to each of the BFT packets. Example beam management setup information may include, among other things, the total number of BFT packets to be sent by the AP (N), the number of TX and RX antennas or sectors associated with the AP, or the total number of BFT packets allowed to be sent by the STA (K).

[0129] In some aspects, the trigger frame may further provide a timing and frequency reference for wireless communication on the directional link. For example, the beam management setting information may include timing and frequency information indicating the timing of wireless communication on the directional link and a CFO associated with the wireless communication on the directional link. In other words, the STA knows that it will be on the directional link at time t based on the timing information included in the trigger frame or derived from receiving the trigger frame.1 Perform beamforming training operations. In addition, the STA may estimate the CFO associated with wireless communication on the directional link based on frequency information (such as L-STF) included in the trigger frame. Therefore, when a trigger frame associated with a beamforming training operation is received, the L-STF may not be present in each BFT packet sent on the directional link. Fig.14A In the example of FIG. 4 , each BFT packet in the BFT packets is depicted as a short training sequence (TS).

[0130] At time t 1 , the AP initiates a beamforming training operation by sending N training sequences in various TX beam directions over a directional link. More specifically, at least one training sequence may be sent by each TX sector associated with the AP (such as Figure 6 In some aspects, the STA may determine the sector ID (of the AP) from which the training sequence is sent based on the trigger frame received on the anchor link (at time t0) and the timing of each training sequence (such as indicated by a timestamp). In some other aspects, each training sequence in the training sequence may carry beam management information that explicitly signals one or more training parameters. More specifically, the beam management information may include any information that has not been signaled via a trigger frame. In some specific implementations, each training sequence in the training sequence may consist of a single LTF (such as an L-LTF) designed to indicate one or more beam management parameters (such as a sector ID). In some other specific implementations, each training sequence in the training sequence may consist of an LTF and a signal field (such as an L-SIG) to carry additional beam management information (such as a training direction, a beam tracking request, the number of remaining training sequences to be sent (M), or an antenna ID).

[0131] The STA receives one or more training sequences in the training sequence and compares the signal power of the received training sequences. 2 , the STA provides feedback (FB) on the directional link indicating which of the training sequences has the highest received signal power. In some implementations, the feedback may consist of a single LTF (such as L-LTF) designed to indicate the best sector ID. In some other implementations, the feedback may consist of an LTF and a signal field (such as L-SIG) to carry additional information, such as the best antenna ID or SNR report. In some implementations, the STA may further train its RX antennas for RX beamforming (at time t 1 to 2 In some other implementations, the STA may perform an additional packet exchange with the AP (at time t 2 and t 3In some aspects, the AP may train its RX antenna for RX beamforming based on the additional packet exchange. In some other aspects, the STA may train its TX antenna for TX beamforming based on the additional packet exchange.

[0132] At time t 3 , the AP sends SP scheduling information on the directional link, which allocates SPs for directional communication with STAs. In some aspects, the SP scheduling information may be sent on the anchor link (such as Fig. 14B Because the anchor link is synchronized with the directional link in time, the STA knows that the SP is scheduled to be on the directional link from time t 4 to 6 In some other aspects, SP scheduling information may be sent over a directional link (such as a reference Fig. 9 and Fig.10 ). In some implementations, the AP may unilaterally assign a STA to a specific SP. In some other implementations, the STA may request to be assigned to a specific SP. In such implementations, the AP and the STA may negotiate a SP schedule for subsequent wireless communications over the directional link.

[0133] At time t 4 , the AP initiates TX data transmission on the directional link using the beam determined based on the beamforming training operation. For example, the AP may initiate TX data transmission on the directional link via 2 In some aspects, the STA may receive TX data via the best RX sector determined based on the beamforming training operation. At time t 5 , the STA sends an ACK or block ACK to confirm receipt of the TX data. In some implementations, the ACK or block ACK may be sent over a directional link (such as Fig. 14B In some other implementations, an ACK or a block ACK may be sent on the anchor link.

[0134] Fig.15 1 is a flowchart illustrating an example process 1500 for wireless communication supporting a 60 GHz operating mode of a WLAN. In some implementations, the process 1500 may be performed by an AP (such as Figure 6 and Figure 8 AP 610 or 810, or Figure 7 Any of the APMLD 710) is executed.

[0135] In some implementations, process 1500 begins at block 1502, where one or more management frames announcing a BSS associated with an AP are sent over a first wireless communication link. In block 1504, process 1500 continues to associate with a STA over a wireless communication link based on the one or more management frames. In block 1506, process 1500 continues to perform a beamforming training operation with the STA over a second wireless communication link based on associating with the STA over the first wireless communication link. In block 1508, process 1500 continues to communicate with the STA over the second wireless communication link using a beam based on the beamforming training operation. In some implementations, the first wireless communication link may operate at a carrier frequency below 7 GHz, and the second wireless communication link may operate at a carrier frequency above 7 GHz.

[0136] In some aspects, process 1500 may also include exchanging beam management setup information with the STA over the first wireless communication link, wherein the beam management setup information signals the start of the beamforming training operation. In some implementations, the beam management setup information may include frequency information indicating a CFO associated with wireless communication on the second wireless communication link. In some implementations, the beam management setup information may include timing information indicating the timing of wireless communication on the second wireless communication link. In some implementations, process 1500 may also include sending scheduling information over the first wireless communication link, the scheduling information allocating an SP for communication with the STA over the second wireless communication link.

[0137] In some aspects, the execution of the beamforming training operation may include sending multiple PPDUs in multiple directions on a second wireless communication link, each of which consists of a single PHY training field; and receiving feedback from the STA in response to sending multiple PPDUs, wherein the feedback indicates the direction for tuning multiple antennas. In some specific implementations, the AP may communicate with the STA via the second wireless communication link via multiple antennas tuned in the direction indicated by the feedback. In some specific implementations, the feedback may be carried in a PPDU consisting of a single PHY training field. In some other specific implementations, the feedback may be carried in a PPDU consisting of a single PHY training field and a single PHY signal field. In some specific implementations, the feedback may be received on the second wireless communication link. In some other specific implementations, the feedback may be received on the first wireless communication link.

[0138] Fig.16 1600 is a flowchart illustrating an example process 1600 for wireless communication supporting a 60 GHz operating mode of a WLAN. In some implementations, the process 1600 may be performed by a STA (such as a Figure 6 and Figure 8STA 620 or 820, or Figure 7 any of the non-AP MLDs 720).

[0139] In some implementations, process 1600 begins at block 1602, where one or more management frames are received over a first wireless communication link that announce a BSS associated with an AP. In block 1604, process 1600 continues to associate with the AP over the wireless communication link based on the one or more management frames. In block 1606, process 1600 continues to perform a beamforming training operation with the AP over a second wireless communication link based on associating with the AP over the first wireless communication link. In block 1608, process 1600 continues to communicate with the AP over the second wireless communication link using a beam based on the beamforming training operation. In some implementations, the first wireless communication link may operate at a carrier frequency below 7 GHz, and the second wireless communication link may operate at a carrier frequency above 7 GHz.

[0140] In some aspects, process 1600 may also include exchanging beam management setup information with the AP over the first wireless communication link, the beam management setup information signaling the start of the beamforming training operation. In some implementations, the beam management setup information may include frequency information indicating a CFO associated with wireless communication over the second wireless communication link. In some implementations, the beam management setup information may include timing information indicating the timing of wireless communication over the second wireless communication link. In some implementations, process 1600 may also include receiving scheduling information over the first wireless communication link, the scheduling information allocating an SP for communication with the AP over the second wireless communication link.

[0141] In some aspects, the execution of the beamforming training operation may include sending multiple PPDUs in multiple directions on a second wireless communication link, each of which consists of a single PHY training field; and receiving feedback from the AP in response to sending the multiple PPDUs, wherein the feedback indicates the direction for tuning multiple antennas. In some specific implementations, the STA may communicate with the AP via the second wireless communication link via multiple antennas tuned in the direction indicated by the feedback. In some specific implementations, the feedback may be carried in a PPDU consisting of a single PHY training field. In some other specific implementations, the feedback may be carried in a PPDU consisting of a single PHY training field and a single PHY signal field. In some specific implementations, the feedback may be received on the second wireless communication link. In some other specific implementations, the feedback may be received on the first wireless communication link.

[0142] Fig.17FIG. 1 is a block diagram of an example AP 1700 according to some implementations. In some implementations, the AP 1700 is configured to perform the above-referenced Fig.15 The process 1500 described above. AP 1700 may be Figure 5A Example implementations of the described AP 502 or WCD 510. For example, the AP 1700 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (eg, a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0143] AP 1700 includes a receiving component 1710, a communication manager 1720, and a sending component 1730. Communication manager 1720 also includes a BSS announcement component 1722, an anchor link association component 1724, a beamforming training component 1726, and a directional communication component 1728. Portions of one or more of components 1722-1728 may be implemented at least in part in hardware or firmware. In some implementations, at least one of components 1722, 1724, 1726, or 1728 is implemented at least in part as a memory (such as a memory device). Figure 5A Memory 540 or Figure 4 For example, portions of one or more of components 1722-1728 may be implemented as software that can be executed by a processor such as Figure 5A The application processor 530 or Figure 4 The processor 406 of the device 408 executes non-transitory instructions (or "code") to perform the functions or operations of the corresponding components.

[0144] The receiving component 1710 is configured to receive RX signals from one or more STAs through a wireless channel. The sending component 1730 is configured to send TX signals to one or more STAs through a wireless channel. The communication manager 1720 is configured to control or manage communications with one or more STAs. In some specific implementations, the BSS announcement component 1722 may send one or more management frames announcing the BSS associated with the AP on the first wireless communication link; the anchor link association component 1724 may associate with the STA through the first wireless communication link based on the one or more management frames; the beamforming training component 1726 may perform a beamforming training operation with the STA through the second wireless communication link based on the association with the STA through the first wireless communication link; and the directional communication component 1728 may use a beam based on the beamforming training operation to communicate with the STA through the second wireless communication link.

[0145] Fig.18FIG. 1 shows a block diagram of an example STA 1800 according to some specific implementations. In some specific implementations, the STA 1800 is configured to perform the above reference Fig.16 The process 1600 described above. STA 1800 may be Figure 5B Example implementations of the described STA 504 or WCD 515. For example, the STA 1800 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (eg, a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0146] STA 1800 includes a receiving component 1810, a communication manager 1820, and a sending component 1830. The communication manager 1820 also includes a BSS discovery component 1822, an anchor link association component 1824, a beamforming training component 1826, and a directional communication component 1828. Portions of one or more of components 1822-1828 may be implemented at least in part in hardware or firmware. In some specific implementations, at least one of components 1822, 1824, 1826, or 1828 is implemented at least in part as a memory (such as Figure 5B Memory 545 or Figure 4 For example, portions of one or more of components 1822-1828 may be implemented as software that can be executed by a processor such as Figure 5B The application processor 535 or Figure 4 The processor 406 of the device 408 executes non-transitory instructions (or "code") to perform the functions or operations of the corresponding components.

[0147] The receiving component 1810 is configured to receive an RX signal from the AP through a wireless channel. The sending component 1830 is configured to send a TX signal to the AP through a wireless channel. The communication manager 1720 is configured to control or manage communication with the AP. In some specific implementations, the BSS discovery component 1822 may receive one or more management frames that announce the BSS associated with the AP on the first wireless communication link; the anchor link association component 1824 may associate with the AP through the first wireless communication link based on the one or more management frames; the beamforming training component 1826 may perform a beamforming training operation with the AP through the second wireless communication link based on the association with the AP through the first wireless communication link; and the directional communication component 1828 may use a beam based on the beamforming training operation to communicate with the AP through the second wireless communication link.

[0148] Each specific implementation example is described in the following numbered clauses:

[0149] 1. A method for wireless communication by a wireless access point (AP), the method comprising:

[0150] sending, over a first wireless communication link, one or more management frames advertising a basic service set (BSS) associated with the AP;

[0151] associating with a wireless station (STA) over the first wireless communication link based on the one or more management frames;

[0152] performing a beamforming training operation with the STA through a second wireless communication link based on associating with the STA through the first wireless communication link; and

[0153] The STA is communicated with via the second wireless communication link using a beam based on the beamforming training operation.

[0154] 2. The method of clause 1, wherein the first wireless communication link operates at a carrier frequency below 7 GHz and the second wireless communication link operates at a carrier frequency above 7 GHz.

[0155] 3. The method according to any one of clauses 1 or 2, further comprising:

[0156] The beam management setting information is exchanged with the STA through the first wireless communication link, and the beam management setting information signals the start of the beamforming training operation.

[0157] 4. A method according to any one of clauses 1 to 3, wherein the beam management setting information includes frequency information indicating a carrier frequency offset (CFO) associated with wireless communication on the second wireless communication link.

[0158] 5. A method according to any of clauses 1 to 4, wherein the beam management setup information includes timing information indicating the timing of wireless communication on the second wireless communication link.

[0159] 6. A method according to any of clauses 1 to 5, wherein the performing of the beamforming training operation comprises:

[0160] transmitting a plurality of physical layer (PHY) convergence protocol (PLCP) protocol data units (PPDUs) in respective directions over the second wireless communication link, each PPDU of the plurality of PPDUs consisting of a single PHY training field; and

[0161] Feedback is received from the STA in response to transmitting the plurality of PPDUs, the feedback indicating directions for tuning a plurality of antennas.

[0162] 7. A method according to any of clauses 1 to 6, wherein the feedback is carried in a PPDU consisting of a single PHY training field.

[0163] 8. A method as described in any of clauses 1 to 6, wherein the feedback is carried in a PPDU consisting of a single PHY Training field and a single PHY SIGNAL field.

[0164] 9. A method according to any of clauses 1 to 8, wherein the feedback is received over the second wireless communication link.

[0165] 10. A method according to any of clauses 1 to 8, wherein the feedback is received over the first wireless communication link.

[0166] 11. The method of any of clauses 1 to 10, wherein the AP communicates with the STA over the second wireless communication link via the multiple antennas tuned in the direction indicated by the feedback.

[0167] 12. The method according to any one of clauses 1 to 11, further comprising:

[0168] Scheduling information is sent over the first wireless communication link, the scheduling information allocating a service period (SP) for communication with the STA over the second wireless communication link.

[0169] 13. A wireless access point (AP), the AP comprising:

[0170] at least one memory; and

[0171] at least one processor communicatively coupled to the at least one memory, the at least one processor configured to cause the AP to:

[0172] sending, over a first wireless communication link, one or more management frames advertising a basic service set (BSS) associated with the AP;

[0173] associating with a wireless station (STA) over the first wireless communication link based on the one or more management frames;

[0174] performing a beamforming training operation with the STA through a second wireless communication link based on associating with the STA through the first wireless communication link; and

[0175] The STA is communicated with via the second wireless communication link using a beam based on the beamforming training operation.

[0176] 14. The AP of clause 13, further comprising:

[0177] A local oscillator (LO) is configured to drive a carrier frequency associated with each of the first wireless communication link and the second wireless communication link.

[0178] 15. An AP according to any of clauses 13 or 14, further comprising:

[0179] A clock is configured to control timing of communications on each of the first wireless communication link and the second wireless communication link.

[0180] 16. A method for wireless communication by a wireless station (STA), the method comprising:

[0181] receiving, over a first wireless communication link, one or more management frames advertising a basic service set (BSS) associated with an access point (AP);

[0182] associating with the AP via the first wireless communication link based on the one or more management frames;

[0183] performing a beamforming training operation with the AP through a second wireless communication link based on associating with the AP through the first wireless communication link; and

[0184] The AP is communicated with via the second wireless communication link using a beam based on the beamforming training operation.

[0185] 17. The method of clause 16, wherein the first wireless communication link operates at a carrier frequency below 7 GHz and the second wireless communication link operates at a carrier frequency above 7 GHz.

[0186] 18. The method according to any one of clauses 16 or 17, further comprising:

[0187] Beam management setup information is exchanged with the AP over the first wireless communication link, the beam management setup information signaling the start of the beamforming training operation.

[0188] 19. A method according to any of clauses 16 to 18, wherein the beam management setting information comprises frequency information indicative of a carrier frequency offset (CFO) associated with wireless communication on the second wireless communication link.

[0189] 20. A method according to any of clauses 16 to 19, wherein the beam management setup information comprises timing information indicative of timing of wireless communications on the second wireless communication link.

[0190] 21. A method according to any of clauses 16 to 20, wherein the performing of the beamforming training operation comprises:

[0191] transmitting a plurality of physical layer (PHY) convergence protocol (PLCP) protocol data units (PPDUs) in respective directions over the second wireless communication link, each PPDU of the plurality of PPDUs consisting of a single PHY training field; and

[0192] Feedback is received from the AP in response to transmitting the plurality of PPDUs, the feedback indicating directions for tuning a plurality of antennas.

[0193] 22. A method as described in any of clauses 16 to 21, wherein the feedback is carried in a PPDU consisting of a single PHY training field.

[0194] 23. A method as described in any of clauses 16 to 21, wherein the feedback is carried in a PPDU consisting of a single PHY Training field and a single PHY SIGNAL field.

[0195] 24. A method as described in any of clauses 16 to 23, wherein the feedback is received over the second wireless communication link.

[0196] 25. A method as described in any of clauses 16 to 23, wherein the feedback is received over the first wireless communication link.

[0197] 26. The method of any of clauses 16 to 25, wherein the STA communicates with the AP over the second wireless communication link via the multiple antennas tuned in the direction indicated by the feedback.

[0198] 27. The method according to any one of clauses 16 to 26, further comprising:

[0199] Scheduling information is received over the first wireless communication link, the scheduling information allocating a service period (SP) for communication with the AP over the second wireless communication link.

[0200] 28. A wireless station (STA), the STA comprising:

[0201] at least one memory; and

[0202] at least one processor communicatively coupled to the at least one memory, the at least one processor configured to cause the STA to:

[0203] receiving, over a first wireless communication link, one or more management frames advertising a basic service set (BSS) associated with an access point (AP);

[0204] associating with the AP via the first wireless communication link based on the one or more management frames;

[0205] performing a beamforming training operation with the AP through a second wireless communication link based on associating with the AP through the first wireless communication link; and communicating with the AP through the second wireless communication link using a beam based on the beamforming training operation.

[0206] 29. The STA of clause 28, further comprising:

[0207] A local oscillator (LO) is configured to drive a carrier frequency associated with each of the first wireless communication link and the second wireless communication link.

[0208] 30. A STA as described in any of clauses 28 or 29, further comprising:

[0209] A clock is configured to control timing of communications on each of the first wireless communication link and the second wireless communication link.

[0210] As used herein, a phrase referring to "at least one of" or "one or more of" a list of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover the following possibilities: only a, only b, only c, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a, b, and c. As used herein, "based on" is intended to be interpreted in an inclusive sense, unless otherwise expressly indicated. For example, "based on" can be used interchangeably with "based at least in part on," unless otherwise expressly indicated. Specifically, unless the phrase in the context refers to "based only on 'one'" or an equivalent, whether it is "based on 'one'" or "based at least in part on 'one'" can be based on "one" alone or on a combination of "one" and one or more other factors, conditions, or information.

[0211] The various illustrative components, logic, logic blocks, modules, circuits, operations, and algorithmic processes described in conjunction with the specific implementations disclosed herein may be implemented as electronic hardware, firmware, software, or a combination of hardware, firmware, or software, including the structures disclosed in this specification and their structural equivalents. This interchangeability of hardware, firmware, and software has been generally described in terms of their functionality and exemplified in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware, firmware, or software depends on the specific application and the design constraints imposed on the overall system.

[0212] Various modifications to the specific implementations described in this disclosure will be apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other specific implementations without departing from the spirit or scope of the disclosure. Therefore, the claims are not intended to be limited to the specific implementations shown herein, but are to be accorded the widest scope consistent with the disclosure, the principles and novel features disclosed herein.

[0213] Additionally, various features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, individual features described in the context of a single implementation may also be implemented in multiple implementations individually or in any suitable subcombination. Thus, although features may be described above as functioning in a particular combination, and even initially claimed as such, one or more features from a claimed combination may in some cases be deleted from the combination, and a claimed combination may be directed to a subcombination or a variation of a subcombination.

[0214] Similarly, although operations are depicted in a specific order in the figure, this should not be understood as requiring such operations to be performed in the specific order shown or in a sequential order, or to perform all illustrated operations to achieve the desired result. In addition, the accompanying drawings may schematically depict one or more example processes in the form of a flow chart or a flow diagram. However, other operations not depicted may be incorporated into the example processes schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously or between any operations in the illustrated operations. In some environments, multitasking and parallel processing may be advantageous. In addition, the separation of each system component in the specific implementation described above should not be understood as requiring such separation in all specific implementations, but it should be understood as the described program components and system can usually be integrated together in a single software product, or be packaged in multiple software products.

Claims

1. A method for wireless communication by a wireless access point (AP), the method comprising: sending, over a first wireless communication link, one or more management frames advertising a basic service set (BSS) associated with the AP; associating with a wireless station (STA) over the first wireless communication link based on the one or more management frames; performing a beamforming training operation with the STA through a second wireless communication link based on associating with the STA through the first wireless communication link; as well as The STA is communicated with via the second wireless communication link using a beam based on the beamforming training operation. 2 . The method of claim 1 , wherein the first wireless communication link operates at a carrier frequency below 7 GHz and the second wireless communication link operates at a carrier frequency above 7 GHz.

3. The method according to claim 1, further comprising: The beam management setting information is exchanged with the STA through the first wireless communication link, and the beam management setting information signals the start of the beamforming training operation.

4. The method of claim 3, wherein the beam management setting information includes frequency information indicating a carrier frequency offset (CFO) associated with wireless communication on the second wireless communication link. 5 . The method of claim 3 , wherein the beam management setup information includes timing information indicating timing of wireless communications on the second wireless communication link.

6. The method of claim 1 , wherein the performing of the beamforming training operation comprises: transmitting a plurality of physical layer (PHY) convergence protocol (PLCP) protocol data units (PPDUs) in respective directions over the second wireless communication link, each PPDU of the plurality of PPDUs consisting of a single PHY training field; and Feedback is received from the STA in response to transmitting the plurality of PPDUs, the feedback indicating directions for tuning a plurality of antennas.

7. The method of claim 6, wherein the feedback is carried in a PPDU consisting of a single PHY training field.

8. The method of claim 6, wherein the feedback is carried in a PPDU consisting of a single PHY training field and a single PHY signal field.

9. The method of claim 6, wherein the feedback is received over the second wireless communication link.

10. The method of claim 6, wherein the feedback is received over the first wireless communication link.

11. The method of claim 6, wherein the AP communicates with the STA over the second wireless communication link via the multiple antennas tuned in the direction indicated by the feedback.

12. The method according to claim 1, further comprising: Scheduling information is sent over the first wireless communication link, the scheduling information allocating a service period (SP) for communication with the STA over the second wireless communication link.

13. A wireless access point (AP), the AP comprising: at least one memory; and at least one processor communicatively coupled to the at least one memory, the at least one processor configured to cause the AP to: sending, over a first wireless communication link, one or more management frames advertising a basic service set (BSS) associated with the AP; associating with a wireless station (STA) over the first wireless communication link based on the one or more management frames; performing a beamforming training operation with the STA through a second wireless communication link based on associating with the STA through the first wireless communication link; as well as The STA is communicated with via the second wireless communication link using a beam based on the beamforming training operation.

14. The AP according to claim 13, further comprising: A local oscillator (LO) is configured to drive a carrier frequency associated with each of the first wireless communication link and the second wireless communication link.

15. The AP according to claim 13, further comprising: A clock is configured to control timing of communications on each of the first wireless communication link and the second wireless communication link.

16. A method for wireless communication by a wireless station (STA), the method comprising: receiving, over a first wireless communication link, one or more management frames advertising a basic service set (BSS) associated with an access point (AP); associating with the AP via the first wireless communication link based on the one or more management frames; performing a beamforming training operation with the AP through a second wireless communication link based on associating with the AP through the first wireless communication link; as well as The AP is communicated with via the second wireless communication link using a beam based on the beamforming training operation.

17. The method of claim 16, wherein the first wireless communication link operates at a carrier frequency below 7 GHz and the second wireless communication link operates at a carrier frequency above 7 GHz.

18. The method according to claim 16, further comprising: Beam management setup information is exchanged with the AP over the first wireless communication link, the beam management setup information signaling the start of the beamforming training operation.

19. The method of claim 18, wherein the beam management setting information includes frequency information indicating a carrier frequency offset (CFO) associated with wireless communication on the second wireless communication link.

20. The method of claim 18, wherein the beam management setup information includes timing information indicating timing of wireless communications on the second wireless communication link.

21. The method of claim 16, wherein the performing of the beamforming training operation comprises: transmitting a plurality of physical layer (PHY) convergence protocol (PLCP) protocol data units (PPDUs) in respective directions over the second wireless communication link, each PPDU of the plurality of PPDUs consisting of a single PHY training field; and Feedback is received from the AP in response to transmitting the plurality of PPDUs, the feedback indicating directions for tuning a plurality of antennas.

22. The method of claim 21, wherein the feedback is carried in a PPDU consisting of a single PHY training field.

23. The method of claim 21, wherein the feedback is carried in a PPDU consisting of a single PHY Training field and a single PHY Signal field.

24. The method of claim 21, wherein the feedback is received over the second wireless communication link.

25. The method of claim 21, wherein the feedback is received over the first wireless communication link.

26. The method of claim 21, wherein the STA communicates with the AP over the second wireless communication link via the multiple antennas tuned in the direction indicated by the feedback.

27. The method according to claim 16, further comprising: Scheduling information is received over the first wireless communication link, the scheduling information allocating a service period (SP) for communication with the AP over the second wireless communication link.

28. A wireless station (STA), the STA comprising: at least one memory; and at least one processor communicatively coupled to the at least one memory, the at least one processor configured to cause the AP to: receiving, over a first wireless communication link, one or more management frames advertising a basic service set (BSS) associated with an access point (AP); associating with the AP via the first wireless communication link based on the one or more management frames; performing a beamforming training operation with the AP through a second wireless communication link based on associating with the AP through the first wireless communication link; as well as The AP is communicated with via the second wireless communication link using a beam based on the beamforming training operation.

29. The STA according to claim 28, further comprising: A local oscillator (LO) is configured to drive a carrier frequency associated with each of the first wireless communication link and the second wireless communication link.

30. The STA according to claim 28, further comprising: A clock is configured to control timing of communications on each of the first wireless communication link and the second wireless communication link.

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