A method for enabling multi-link millimeter wave beam training

Abstract

A method for enabling multilink millimeter wave (mmW) beam training is provided herein. The method, performed by a station (STA), may include receiving a null data packet (NDP) announcement (NDPA) frame on a sub-7 GHz link of the STA, where the NDPA includes information for initiating a millimeter wave (mmW) beam training process, determining that at least one STA Info field included in the NDPA frame includes an AID subfield that matches an association ID (AID) associated with the STA, receiving one or more NDP physical layer protocol data units (PPDUs) on the mmW link based on the information included in the STA Info field, and transmitting, on the sub-7 GHz link, a beam training feedback report based on the one or more NDP PPDUs received on the mmW link.

Description

[Background technology]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 427,006, filed November 21, 2022, the contents of which are incorporated herein by reference.

[0002] A wireless local area network (WLAN) in infrastructure basic service set (BSS) mode has an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic within and out of the BSS. Traffic to a STA originating from outside the BSS arrives through the AP and is delivered to the STA. Traffic originating from a STA to a destination outside the BSS is sent to the AP to be delivered to the respective destination. Traffic between STAs within a BSS may also be sent through the AP, where the source STA sends traffic to the AP and the AP delivers the traffic to the destination STA.

[0003] Using the 802.11ac infrastructure mode of operation, an AP can transmit beacons on a fixed channel, usually the primary channel. This channel, which may be 20 MHz wide, is the operating channel of the BSS. This channel is also used by STAs to establish connections with the AP. The basic channel access mechanism in 802.11 systems is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). In this mode of operation, every STA, including the AP, can sense the primary channel. If the channel is detected as busy, the STA backs off. Therefore, only one STA can transmit in a given BSS at any given time.

[0004] In 802.11n, high-throughput (HT) STAs can also use 40 MHz wide channels for communication, which is achieved by combining a primary 20 MHz channel with an adjacent 20 MHz channel to form a 40 MHz wide contiguous channel.

[0005] In 802.11ac, very high-throughput (VHT) STAs can support 20 MHz, 40 MHz, 80 MHz, and 160 MHz-wide channels. 40 MHz and 80 MHz channels are formed by combining contiguous 20 MHz channels, similar to 802.11n described above. A 160 MHz channel can be formed either by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, sometimes referred to as an 80+80 configuration. In the 80+80 configuration, after channel encoding, the data is passed through a segment parser that splits it into two streams. An inverse discrete Fourier transform (IDFT) operation and time-domain processing are performed separately for each stream. The streams are then mapped onto two channels, and the data is transmitted. At the receiver, this mechanism is reversed, and the combined data is sent to the MAC.

[0006] To improve spectral efficiency, 802.11ac introduced the concept of downlink multi-user MIMO (MU-MIMO) transmission to multiple STAs in the same symbol time frame, e.g., during a downlink OFDM symbol. The possibility of using downlink MU-MIMO is also currently being considered for 802.11ah. It is important to note that because downlink MU-MIMO uses the same symbol timing for multiple STAs, as it does in 802.11ac, interference of waveform transmissions to multiple STAs is not an issue. However, all STAs involved in MU-MIMO transmission with the AP must use the same channel or band, which limits the operating bandwidth to the smallest channel bandwidth supported by the STAs involved in MU-MIMO transmission with the AP. Summary of the Invention [Means for solving the problem]

[0007] A method for enabling multi-link millimeter wave (mmW) beam training is provided herein. The method, performed by a station (STA), may include receiving a null data packet (NDP) announcement (NDPA) frame on a sub-7 GHz link of the STA, the NDPA including information for initiating a millimeter wave (mmW) beam training process, determining that at least one STA Info field included in the NDPA frame includes an AID subfield that matches an Association ID (AID) associated with the STA, receiving one or more NDP physical layer protocol data units (PPDUs) on the mmW link based on the information included in the STA Info field, and transmitting, on the sub-7 GHz link, a beam training feedback report based on the one or more NDP PPDUs received on the mmW link.

[0008] The NDPA may include a Common Info field, which may include at least one of a Ver subfield, a Dialogue Token Number subfield, a STA Info Size subfield, a BW subfield, a Channel Puncturing Info subfield, an Nt subfield, an Nr subfield, a Number of Tx Sectors subfield, a Number of Rx Sectors subfield, a Number of NDP subfield, a Number of LTFs in each NDP subfield, or an NDP Tx Power subfield.

[0009] The STA Info field may include at least one of an AID11 subfield, a Preferred Tx Sector ID subfield, a Preferred Rx Sector ID subfield, a BW subfield, an mmW Link ID subfield, an SNR-report Required subfield, or a Blockage SNR Threshold subfield.

[0010] One or more NDP PPDUs may include at least one of an mmW U-SIG field or an mmW-SIG field. The mmW U-SIG field may include at least one of a PHY Version subfield, a Bandwidth subfield, an mmW Band subfield, a Direction subfield, a BSS Color subfield, a TXOP subfield, a PPDU Type subfield, a Channel Puncturing Info subfield, an mmW-SIG MCS subfield, or an mmW-SIG Symbol Number subfield. The mmW-SIG field may include at least one of a Sector Number subfield, an NDP ID subfield, a Sector ID subfield, an Antenna ID subfield, an LTF Size subfield, or an LTF Number subfield. [Brief explanation of the drawings]

[0011] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements and in which:

[0012] [Figure 1A] 1 illustrates an exemplary communication system in which one or more embodiments may be implemented. [Figure 1B] 1B is a system diagram illustrating an exemplary wireless transmit / receive unit (WTRU) that may be used within the communication system of FIG. 1A, according to one embodiment. [Figure 1C] 1B is a system diagram illustrating an exemplary radio access network (RAN) and core network (CN) used within the communication system of FIG. 1A, according to one embodiment. [Figure 1D] FIG. 1B is a system diagram illustrating a further exemplary RAN and CN for use within the communication system of FIG. 1A, according to one embodiment. [Figure 2] FIG. 1 illustrates an exemplary Null Data Packet (NDP) Announcement (NDPA) frame format. [Figure 3] A diagram showing an exemplary sounding dialogue token field format in an NDPA frame. [Figure 4] A diagram showing an exemplary STA Info field format in an Extremely High Throughput (EHT) NDPA frame. [Figure 5] FIG. 1 illustrates an exemplary NDPA frame format for ultra-high reliability (UHR) and mmW support. [Figure 6] FIG. 10 illustrates a first exemplary common Info field format in a UHR mmW NDPA frame. [Figure 7] A diagram showing an exemplary STA info field format in a UHR mmW NDPA frame. [Figure 8] FIG. 10 illustrates a first exemplary mmW beam training NDP frame format. [Figure 9]FIG. 10 illustrates a second exemplary mmW beam training NDP frame format. [Figure 10] FIG. 10 is a diagram of an exemplary frame exchange sequence for a beam training procedure. [Figure 11] 1 is a flowchart illustrating an exemplary beam training procedure. [Figure 12] FIG. 1 illustrates a first exemplary common info field format in a UHR mmW NDPA frame. [Figure 13] A diagram showing an exemplary frame exchange sequence for a time slot-based beam training procedure. [Figure 14] 10 is a flowchart illustrating an exemplary time slot-based beam training procedure. [Figure 15] FIG. 1 illustrates an exemplary beam recovery element format. [Figure 16] FIG. 10 illustrates an exemplary beam recovery control field in a beam recovery element. [Figure 17] FIG. 10 illustrates an example common info field for dynamic configuration of beam recovery procedures. [Figure 18] 1 is a flowchart illustrating an exemplary beam obstruction detection procedure. [Figure 19] 1 is a flowchart illustrating an exemplary beam training procedure. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1A is a system diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail (ZT) unique-word (UW) discrete Fourier transform (DFT) spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), etc.

[0014] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and / or “STA,” may be configured to transmit and / or receive wireless signals, and may include (or be) a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., remote surgery), an industrial device and application (e.g., robots and / or other wireless devices operating in an industrial and / or automated processing chain context), a consumer electronics device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a UE.

[0015] The communications system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communications networks, such as, for example, the CN 106, the Internet 110, and / or the network 112. By way of example, the base stations 114a, 114b may be any of a base transceiver station (BTS), a Node B (NB), an eNodeB (eNB), a Home Node B (HNB), a Home eNodeB (HeNB), a gNode B (gNB), a NR Node B (NR NB), a site controller, an access point (AP), a wireless router, etc. Although the base stations 114a, 114b are each shown as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0016] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, sometimes referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for wireless services in a particular geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and utilize multiple transceivers for each or any sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0017] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0018] More particularly, as mentioned above, the communications system 100 may be a multiple-access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using Wideband CDMA (WCDMA). WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0019] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE Advanced (LTE-A) and / or LTE Advanced Pro (LTE-A Pro).

[0020] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology, such as New Radio (NR) radio access, which may establish the air interface 116 using NR.

[0021] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement LTE radio access and NR radio access, e.g., using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions from / to multiple types of base stations (e.g., eNBs and gNBs).

[0022] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity (Wi-Fi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0023] 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish either a small cell, a picocell, or a femtocell. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 through the CN 106.

[0024] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as different throughput, latency, error resilience, reliability, data throughput, mobility, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A , it will be understood that the RAN 104 and / or CN 106 may be in direct or indirect communication with other RANs employing the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs any of GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or Wi-Fi radio technologies.

[0025] The CN 106 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as TCP, User Datagram Protocol (UDP), and / or IP in the Transmission Control Protocol / Internet Protocol (TCP / IP) Internet protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0026] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may employ cellular-based wireless technology and may be configured to communicate with a base station 114b that may employ IEEE 802.11 wireless technology.

[0027] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other elements / peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the above elements while remaining consistent with an embodiment.

[0028] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be incorporated together, for example, in an electronic package or chip.

[0029] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In one embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0030] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. For example, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0031] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0032] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Furthermore, the processor 118 may access information from and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

[0033] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0034] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or instead of, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of when signals are received from two or more nearby base stations. It will be understood that the WTRU 102 may acquire location information via any suitable location determination method while remaining consistent with an embodiment.

[0035] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules / units that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripherals 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0036] The WTRU 102 may include a full-duplex radio where transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the uplink (e.g., for transmission) and the downlink (e.g., for reception) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and or substantially eliminating self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio that is for transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the uplink (e.g., for transmission) or the downlink (e.g., for reception)).

[0037] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to one embodiment. As mentioned above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0038] The RAN 104 may include eNodeBs 160a, 160b, and 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In an embodiment, the eNodeBs 160a, 160b, and 160c may implement MIMO technology. Thus, the eNodeB 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0039] Each of the eNodeBs 160a, 160b, and 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink (UL) and / or downlink (DL), etc. As shown in FIG. 1C, the eNodeBs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0040] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although each of the above elements is shown as part of the CN 106, it will be understood that any one of these elements may be owned and / or operated by an entity other than the CN operator.

[0041] The MME 162 may be connected to each of the eNodeBs 160a, 160b, and 160c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0042] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as anchoring the user plane during inter-eNodeB handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, etc.

[0043] The SGW 164 may be connected to a PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0044] The CN 106 may facilitate communication with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communication between the WTRUs 102a, 102b, 102c and legacy landline communication devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. Additionally, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0045] Although the WTRU is described in Figures 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments, such a terminal may use a wired communication interface with the communication network (e.g., temporarily or permanently).

[0046] In a representative embodiment, the other network 112 may be a WLAN.

[0047] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access to or interface with a distribution system (DS) or another type of wired / wireless network that carries traffic during and / or from the BSS. Traffic to the STA originating from outside the BSS may arrive through the AP and be delivered to the STA. Traffic originating from the STA to a destination outside the BSS may be sent to the AP for delivery to the respective destination. Traffic between STAs within the BSS may be sent through the AP, e.g., where a source STA may send traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) a source STA and a destination STA via a direct link setup (DLS). In some representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs within or using the IBSS (e.g., all of the STAs) can communicate directly with each other. The IBSS communication mode is sometimes referred to herein as an "ad hoc" communication mode.

[0048] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, an AP can transmit beacons on a fixed channel, such as a primary channel. The primary channel can be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by STAs to establish a connection with the AP. In some representative embodiments, carrier sense multiple access with collision avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. In CSMA / CA, STAs (e.g., every STA), including the AP, can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0049] High-throughput (HT) STAs may use, for example, a 40 MHz wide channel for communication via a combination of a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0050] A very high throughput (VHT) STA can support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz channel and / or an 80 MHz channel can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, sometimes referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data can be passed through a segment parser that can split the data into two streams. Inverse fast Fourier transform (IFFT) processing and time-domain processing can be performed separately for each stream. The streams can be mapped onto two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration can be reversed, and the combined data can be sent to a medium access control (MAC) layer, entity, etc.

[0051] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV white space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support meter-type control / machine-type communication (MTC), such as MTC devices in macro coverage areas. MTC devices can have limited capabilities, including, for example, support for some and / or limited bandwidths (e.g., only support for that). MTC devices can include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0052] WLAN systems that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that can be designated as a primary channel. The primary channel can have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by a STA, from among all STAs operating in the BSS, that supports the smallest bandwidth operating mode. In an 802.11ah example, the primary channel may be 1 MHz wide for a STA (e.g., an MTC-type device) that supports (e.g., only supports) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the status of the primary channel. For example, if a STA (that only supports 1 MHz operating mode) transmits to an AP such that the primary channel is busy, the entire available frequency band may be considered busy, even though most of the frequency band may remain idle and available for use.

[0053] In the United States, the available frequency bands that can be used by 802.11ah are 902 MHz to 928 MHz. In South Korea, the available frequency bands are 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are 916.5 MHz to 927.5 MHz. The total available bandwidth for 802.11ah is 6 MHz to 26 MHz, depending on the country code.

[0054] 1D is a system diagram illustrating the RAN 104 and the CN 106, according to one embodiment. As mentioned above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0055] The RAN 104 may include gNBs 180a, 180b, and 180c, although it will be understood that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNBs 180a and 180b may utilize beamforming to transmit signals to and / or receive signals from the WTRUs 102a, 102b, and 102c. Thus, the gNB 180a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0056] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerologies. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may be different for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., including varying numbers of OFDM symbols and / or varying lengths of absolute time duration).

[0057] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c without accessing any other RAN (e.g., eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c can utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with a gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as an eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeBs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0058] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to user plane functions (UPFs) 184a, 184b, routing of control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with one another via an Xn interface.

[0059] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and at least one Data Network (DN) 185a, 185b. While each of the above elements is shown as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0060] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c, for example, based on the type of service being utilized by the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on Ultra-Reliable Low Latency (URLLC) access, services relying on enhanced Massive Mobile Broadband (eMBB) access, services for MTC access, etc. The AMFs 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as Wi-Fi.

[0061] The SMFs 183a and 183b may be connected to the AMFs 182a and 182b in the CN 106 via an N11 interface. The SMFs 183a and 183b may also be connected to the UPFs 184a and 184b in the CN 106 via an N4 interface. The SMFs 183a and 183b may select and control the UPFs 184a and 184b and configure the routing of traffic through the UPFs 184a and 184b. The SMFs 183a and 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0062] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks such as the Internet 110, for example, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 184a, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0063] The CN 106 may facilitate communication with other networks. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. Additionally, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b through UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0064] 1A-1D and the corresponding description thereof, one or more, or all, of the functions described herein with respect to any of the WTRUs 102a-d, base stations 114a-b, eNodeBs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other element / device(s) described herein may be performed by one or more emulation elements / devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functionality.

[0065] The emulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in a carrier network environment. For example, one or more emulation devices may perform one or more, or all, functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices may perform one or more, or all, functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for testing purposes and / or may perform testing using over-the-air wireless communication.

[0066] The one or more emulation devices may perform one or more functions, inclusive, while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in test labs and / or test scenarios in non-deployed (e.g., test) wired and / or wireless communication networks to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may, for example, include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0067] The IEEE 802.11 UHR Study Group was formed to create a Project Permission Request (PAR) to create an 802.11 Task Group to standardize improved reliability of WLAN connectivity, reduce latency, increase manageability, and increase throughput consumption. Millimeter wave (mmW or mmWave) operation is considered a possible feature to achieve these goals, especially considering the development of multi-link operation (MLO) in 802.11be.

[0068] Millimeter wave operation may be the most relevant feature for UHR purposes. All devices operating in the mmW band / link may be MLO-enabled and may have at least one active sub-7 GHz link. Discovery and association procedures may occur in the lower band / link. Scheduling and broadcasting are from the lower band / link. Beamforming (BF) training with sector sweep (SS) occurs in the mmW band / link, but BF training sequences can be triggered or scheduled from the lower band and feedback may be provided in the lower band.

[0069] MLO allows a non-AP multilink device (MLD) to discover, authenticate, associate, and set up multiple links with an AP MLD. An AP belonging to an AP MLD (called the reporting AP) can advertise the operating capabilities and operating parameters of another AP (called the reported AP) belonging to the same AP MLD by including a multilink element. Each link allows channel access and frame exchange between the non-AP MLD and the AP MLD based on the supported capabilities exchanged during association.

[0070] 2 is an exemplary Null Data Packet (NDP) Announcement (NDPA) frame format 200. The NDPA frame may include a Frame Control field 202, a Duration field 204, an RA field 206, a TA field 208, a Sounding Dialogue Token field 210, one or more STA Info fields 212, and an FCS field 214.

[0071] 3 is an example sounding dialog token field format 300 in an NDPA frame. The sounding dialog token field can include an NDPA variant field 302 and a sounding dialog token number field 304. As described in Table 1 below, in 802.11, there can be four variants of NDPA according to the definition of the sounding dialog token field.

[0072] [Table 1]

[0073] 4 is an example STA Info field format 400 in an EHT NDPA frame. The STA Info field may include an AID11 field 402, a Partial BW Info field 404, a Reserved field 406, an Nc index field 408, a Feedback Type and Ng field 410, a Disambiguation field 412, a Codebook Size field 414, and a Reserved field 416.

[0074] One potential problem with mmW signals is that they are susceptible to changes in the propagation environment and may have inherent limitations due to high propagation loss. Beamforming is a mandatory requirement for successful operation in mmW. Analog beamforming may be better for mmW operation due to reduced complexity. Locking on to the best beam for transmission and reception may require frequent beam training. Under a multi-link operation (MLO) framework, it may be more efficient to use links in the sub-7 GHz band to exchange control frames (such as NDPA frames and trigger frames), but physical layer protocol data units (PPDUs) containing training symbols (such as NDP) should be transmitted in the mmW link. Beam training using the MLO framework requires defining methods and procedures to enable efficient operation in mmW.

[0075] A second potential problem is that the best transmission beam used for data transmission may be disturbed due to mobility or environmental changes of non-AP STAs. In this scenario, the AP STA or non-AP STA can initiate a beam recovery procedure to lock onto a clean beam and resume transmission to the non-AP STA or AP STA, respectively. The beam recovery procedure can be efficient in minimizing latency and improving connectivity reliability. An efficient beam recovery procedure in mmW utilizing the MLO framework is an open problem.

[0076] In one embodiment, the NDPA frame may be used to announce the transmission of an NDP that may be used for beam training and sector sweeping in an mmW link. The NDPA may be sent over a sub-7 GHz link, and the NDP transmission may occur over the mmW link.

[0077] In one embodiment, the sounding dialogue token field of the NDPA frame may be used to indicate that the NDPA is a UHR variant NDPA or an mmW variant NDPA. One or more bits B2 through B7 of the sounding dialogue token may be used to identify the new variant of the NDPA frame (i.e., UHR NDPA or mmW NDPA).

[0078] In one embodiment, one or more Special STA Info fields may be used in legacy NDPA designs to signal common useful information to all addressed STAs in the NDPA. The Special STA Info fields may be indicated by using a Special ID in the AID11 subfield, as shown in Figure 4.

[0079] Figure 5 is an example NDPA frame format 500 for UHR and mmW support. In one embodiment, an NDPA control frame may be defined for UHR and mmW operation with a design as shown in Figure 5. As shown in Figure 5, the NDPA frame may include a Frame Control field 502, a Duration field 504, an RA field 506, a TA field 508, a Common Info field 510, a STA Info List field 512, and an FCS field 514.

[0080] The STA Info field shown in Figure 5 is 4 octets, but it can be of different sizes that can be indicated in the Common Info field for flexible and efficient use of NDPA frames for different purposes. The size N of the Common Info field can be one octet or more.

[0081] Figure 6 is an example common info field 510 format 600 of the UHR mmW NDPA frame shown in Figure 5. As shown in Figure 6, the common info field may include a Ver subfield 602, a dialog token subfield 604, a size of the STA info subfield 606, a BW subfield 608, a channel puncturing info subfield 610, an Nt subfield 612, an Nr subfield 614, a number of Tx sectors subfield 616, a number of Rx sectors subfield 618, a number of NDPs subfield 620, a number of LTFs in each NDP subfield 622, and an NDP Tx power subfield 624. The common info field is defined in the NDPA frame and may be used to indicate common useful information to all addressed STAs in the NDPA, which may include version information to indicate the version of the NDPA for future compatibility as shown in Figure 5.

[0082] The Ver subfield 602 may indicate the version of the NDPA. The Ver subfield 602 may be used for future compatibility, where several different variants of the NDPA may be defined in different revisions, such that the parsing of the Common Info field, the Special STA Info field, and the STA Info field may be different for different revisions, or even different uses of the same revision. For example, there may be a UHR sounding variant of the NDPA that may be used for channel sounding in the sub-7 GHz band in UHR, and another variant that may be used for extended sensing or extended ranging purposes. There may also be variants for mmW beam training and sector sweeping, and another variant for mmW channel sounding.

[0083] [Table 2]

[0084] The dialog token number subfield 604 may be chosen by the AP to identify the current session of beam training so that the beam training report will only be associated with the beam training session.

[0085] The STA Info Size subfield 606 can explicitly indicate the size in octets of the STA Info field in the NDPA frame. The STA Info size can also be implicitly indicated depending on the NDPA frame variant as signaled by the Ver subfield 602.

[0086] The BW subfield 608 may indicate the bandwidth of the NDP to be transmitted on the mmW link SIFS after the NDPA is transmitted on one or more of the sub-7 GHz links. The bandwidth of the PPDU carrying the NDPA and transmitted in the sub-7 GHz band is different from the bandwidth of the NDP PPDU transmitted on the mmW link.

[0087] The Channel Puncturing Info subfield 610 may indicate a list of punctured channels in the BSS mmW link bandwidth over which the NDP may be transmitted.

[0088] The Nt subfield 612 may indicate the number of transmit antennas at the AP.

[0089] The Nr subfield 614 may indicate the number of receive antennas at the AP.

[0090] The Tx Sector Count subfield 616 may indicate the number of transmitting sectors that the AP will support in the downlink, which also corresponds to the number of formed beams in the downlink.

[0091] The Rx Sector Count subfield 618 may indicate the number of receive sectors that the AP will support in the uplink. This subfield also corresponds to the number of receive beams in the uplink.

[0092] The NDP count subfield 620 may indicate the number of NDPs transmitted. The number of NDPs is not necessarily the same as the number of supported sectors. This subfield may indicate the total number of NDPs to be transmitted in the mmW link. Alternatively, this subfield may indicate the number of NDPs transmitted in each transmitting sector.

[0093] The number of LTFs in each NDP subfield 622 may indicate the number of long training fields in each NDP.

[0094] The NDP Tx Power subfield 624 can indicate the combined transmit power across all antennas for the entire BSS mmW bandwidth over which the NDP for beam training is transmitted, or it can indicate the transmit power for each subchannel of the bandwidth used to transmit the NDP PPDU.

[0095] 7 is an example STA Info field format 700 for a UHR mmW NDPA frame. As shown in FIG. 7, the STA Info field can include an AID11 subfield 702, a Preferred Tx Sector ID subfield 704, a Preferred Rx Sector ID subfield 706, a BW subfield 708, an mmW Link ID subfield 710, an SNR Report Required subfield 712, and a Jamming SNR Threshold subfield 714.

[0096] The AID11 subfield 702 may indicate the association ID of the STA to which this STA Info field is addressed.

[0097] The Preferred Tx Sector subfield 704 may indicate the ID of the transmitting sector that was indicated as the preferred transmitting sector in the last beam training session.

[0098] The Preferred Rx Sector subfield 706 may indicate the ID of the transmit sector that was indicated as the preferred receive sector in the last beam training session.

[0099] The BW subfield 708 may indicate the bandwidth of the NDP that should be transmitted on the mmW link SIFS after the NDPA is transmitted on one or more of the sub-7 GHz links.

[0100] The mmW link ID subfield 710 may indicate the ID of the mmW link that will be used to transmit the NDP PPDU used for beam training.

[0101] The SNR Report Required subfield 712 may indicate whether non-AP STAs are required to provide SNR measurements for each transmitting and receiving sector pair.

[0102] The interference SNR threshold subfield 714 may indicate the SNR threshold at which a beam is considered to be in complete interference, may not be used for data transmission or data reception, and should be reported as an obstructed beam.

[0103] 8 is an example mmW beam training NDP frame format 800. As shown in FIG. 8, the mmW beam training frame can include a short training field (STF) 802, a mmW-long training field (LTF) 804, a mmW U-signal (SIG) field 806, and a mmW SIG field 808.

[0104] In one embodiment, the beam training NDP PPDU may include a short preamble with an STF 802 for synchronization, one or more LTFs 804 for beam measurement, and a signal field for signaling beam training information that is essential for identifying the beam. The SIG field may be further divided into an mmW U-SIG field 806 and an mmW SIG field 808. The mmW U-SIG field 806 may be used to signal universal information that is not related to beam training or the PHY layer version. The mmW SIG field 808 may be used to signal information related to beam training as shown in FIG. 8.

[0105] 9 is another example mmW beam training NDP frame format 900. In an embodiment, the beam training NDP PPDU may additionally or alternatively include a synchronization STF (S-STF) 902 that may be used for initial synchronization, a synchronization LTF (S-LTF) 904 that may be used for finer synchronization, an mmW U-SIG field 906, an mmW-SIG field 908, and an mmW-LTF 910.

[0106] In one embodiment, the number of LTFs may be signaled in the NDPA frame and in the SIG field of the beam training NDP PPDU.

[0107] In one embodiment, the mmW U-SIG field may include a PHY version independent field to enable forward compatibility to future modifications following UHR-mmW. The mmW U-SIG field may include the following subfields as listed in Table 3 below:

[0108] [Table 3]

[0109] In one embodiment, the mmW-SIG field may contain beam training information. The mmW-SIG field may include the following subfields as listed in Table 4 below:

[0110] [Table 4]

[0111] 10 illustrates an exemplary frame exchange sequence for the overall training procedure 1000. As shown in FIG. 10, in one embodiment, one AP and one or more non-AP STAs can participate in one or more beam training sessions. The AP 1002 can participate as the initiator of the beam training session, and the non-AP STAs 1004 and 1006 can participate as responders of the beam training session. Different control frames or beam training PPDUs of a beam training session can be sent on different links. For example, a sub-7 GHz link can be used to send control frames, and an mmW link can be used to transmit beam training PPDUs.

[0112] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP can transmit an NDPA on one or more of the sub-7 GHz band links in a TXOP immediately claimed by this AP. The NDPA can be transmitted in a UHR PPDU or any legacy PPDU. The bandwidth of the PPDU carrying the NDPA can be indicated in the SIG field of the PPDU carrying the NDPA. The bandwidth indicated in the common info field, special STA Info field(s), or the STA Info field of the NDPA refers to the bandwidth of the beam training NDP PPDU that will be transmitted immediately after the NDPA.

[0113] In one embodiment, an AP initiating a beam training session and being the holder of the current TXOP can switch to one or more links in the mmW band and transmit a beam training NDP PPDU SIFS after the NDPA is transmitted on the sub-7 GHz band. The NDP PPDU can cover the entire bandwidth of the mmW link as indicated in the common info field, the special STA Info field(s), or the STA Info field of the NDPA. The NDP PPDU can have punctured subchannels within the PPDU's bandwidth, which can also be indicated in the NDPA. One or more NDP PPDUs can be transmitted in each available sector, with each NDP identified by an NDP ID, sector ID, and antenna ID. The number of transmitted NDP PPDUs can be equal to or greater than the number of sectors. The AP STA can sweep to the next sector and transmit the corresponding NDP(s) intended for transmission in this sector. The NDPs can be separated by SIFS or any other inter-frame space (IFS). Each NDP may be transmitted at a transmit power equal to the NDP Tx power as indicated in the NDPA immediately preceding the NDP transmission. The number of LTFs in each NDP PPDU may be indicated in the NDPA and may be greater than or equal to the largest number of receive sectors / beams supported by non-AP STAs participating in the beam training session.

[0114] In one embodiment, the AP that initiates the beam training session and is the holder of the current TXOP can switch back to the sub-7 GHz link and transmit a BFRP or any other trigger or control frame designed to trigger feedback transmissions from non-AP STAs in the uplink.

[0115] In one embodiment, one or more non-AP STAs may participate in a beam training session as responders such that each non-AP STA may be addressed by one or more STA Info fields in the NDPA sent from the AP that is the initiator of the beam training session.

[0116] In one embodiment, a non-AP STA receives an NDPA sent by an AP over a sub-7 GHz link, parses the Dialogue Token field and / or the Common Info field and / or the Special STA Info field(s) to detect whether the NDPA is initiating a beam training session, and collects all information signaled in the aforementioned fields to prepare for the beam training session.

[0117] In one embodiment, a non-AP STA may parse the STA Info list, searching for a STA Info field addressed to it by examining AID 11. If the non-AP STA AID matches one or more STA Info fields in the STA Info list, the non-AP parses the STA Info field(s) and begins preparing for a beam training session. Otherwise, if the non-AP STA AID does not match any of the AIDs 11 of the STA Info fields in the STA Info list, the non-AP STA may stop decoding the NDPA and enter doze mode after setting its NAV counter(s).

[0118] In one embodiment, if a non-AP STA is addressed in the STA info list of an NDPA immediately sent over a sub-7 GHz link, the non-AP STA may switch to the mmW link(s) and prepare to receive an NDP PPDU that may be sent over the mmW link(s) as indicated in the STA Info field.

[0119] In one embodiment, a non-AP STA may switch its receive beam for each LTF symbol or group of LTF symbols included in a received NDP PPDU transmitted in one of the AP's transmit sectors / beams. The non-AP may then measure the SNR, RSSI, or any other physical measurement of the received LTF to represent the strength or quality of the received signal. The non-AP STA may also measure the average SNR, average RSSI, or average of any other physical measurement of the received group of LTFs to represent the strength or quality of the received signal. The non-AP STA may average measurements over multiple NDP PPDUs if the AP transmits more than one NDP PPDU in the same sector / beam. By performing this receive procedure, each non-AP should have a measure of the signal strength or quality of each transmit beam and receive beam pair.

[0120] In one embodiment, if the SNR Report Required subfield in the STA Info field addressed to this non-AP STA is set to 0, the non-AP STA may be required to prepare a complete report for all transmitting and receiving sector combinations; otherwise, the non-AP STA may only prepare a report for the best transmitting and receiving sector pair.

[0121] In one embodiment, if the measured SNR of a given transmit beam and receive beam combination is less than the threshold indicated in the interference SNR threshold subfield of the STA Info field, this transmit beam may be considered to be in complete interference with the considered receive beam, and a special value in the beam training report may indicate this case. In another embodiment, non-AP STAs may only prepare beam training reports for transmit and receive beam pairs with SNR values ​​equal to or greater than the interference SNR threshold.

[0122] In one embodiment, a non-AP STA can prepare a beam training report and send it back to the AP in response to a beam training trigger frame sent to solicit the beam training report. Both the beam training trigger frame and the solicited beam training report can be sent over a sub-7 GHz link.

[0123] 11 is a flowchart illustrating an exemplary beam training procedure 1100. In one embodiment, the beam training procedure described above may be illustrated by the flowchart shown in FIG.

[0124] At 1102, a non-AP STA may receive an NDPA from an AP over a sub-7 GHz link.

[0125] At 1104, the non-AP STA may identify the NDPA variant as the mmW beam training variant.

[0126] At 1106, the non-AP STA may locate the STA Info fields addressed to it by examining the AID11 field of each STA Info field in the STA Info list of the NDPA.

[0127] At 1108, the non-AP STA may determine whether the non-STA AID matches any of the AIDs 11 in the STA info field in the STA Info list. At 1110, if the AIDs 11 do not match, the non-AP STA may stop decoding the NDPA, set one or more NAV counters, and enter doze mode.

[0128] At 1112, if the AID11 matches, the non-AP STA can decode one or more STA Info fields with the matching AID11 and decode the dialog token field, and / or the special STA info field, and / or the common Info field.

[0129] At 1114, the non-AP STA can parse the signaling information, prepare for a beam training session, and switch to one or more mmW links.

[0130] At 1116, the non-AP STA may receive the NDP PPDU sent immediately after the NDPA was sent by the AP.

[0131] At 1118, the non-AP STA may switch its receive beam for each LTF symbol or group of LTF symbols included in a received NDP PPDU transmitted in one of the AP's transmit sectors / beams. The non-AP may then measure the SNR, RSSI, or any other physical measurement of the received LTF to represent the strength or quality of the received signal. The non-AP STA may also measure the average SNR, average RSSI, or average of any other physical measurement of the received group of LTFs to represent the strength or quality of the received signal. The non-AP STA may average measurements over multiple NDP PPDUs if the AP transmits more than one NDP PPDU in the same sector / beam. By performing this receive procedure, each non-AP should have a measure of the signal strength or quality of each pair of transmit and receive beams.

[0132] At 1120, the non-AP STA can switch back to the sub-7 GHz link to receive the beam training trigger frame and send a beam training feedback report back to the AP.

[0133] In one embodiment, beam training for mmW links can take into account a time structure for transmission, in which time slots (time slots) in which NDP training PPDU transmissions occur can be defined.

[0134] In one embodiment, additionally or alternatively, a Common Info field may be defined in the NDPA frame and used to indicate useful information common to all addressed STAs in the NDPA, taking into account time-slotted transmissions.

[0135] 12 is an exemplary additional or alternative design of a common Info field format 1200. The sub-fields of the common Info field in FIG. 12 may be with any possible combination of the common Info frame formats shown in FIG.

[0136] As shown in FIG. 12, additional or alternative designs of the common info field may include a Ver subfield 1202, a Dialogue Token subfield 1204, a BW subfield 1206, a Channel Puncturing Info subfield 1208, an Nt subfield 1210, an Nr subfield 1212, a Number of Tx Sectors subfield 1214, a Number of Time Slots subfield 1216, a Slot Duration subfield 1218, a Slot Start subfield 1220, a Start Time Slot subfield 1222, a Number of LTFs in each NDP subfield 1224, and an NDP Tx Power subfield 1226.

[0137] The Number of Time Slots subfield 1216 may indicate the number of time slots in which the beam training procedure may occur. Each time slot may contain one or more NDP PPDUs that may be used for beam training. The transmission of the first NDP PPDU in each time slot may occur exactly at the beginning of a time slot boundary. Subsequent NDP PPDUs, if any, may be transmitted SIFS after the first NDP PPDU, separated from each other by SIFS. NDP PPDUs may also be transmitted with any inter-frame spacing separation.

[0138] The slot duration subfield 1218 may indicate the duration of each time slot, which may be expressed in units of time (such as μsec) or in number of OFDM symbols.

[0139] The slot start subfield 1220 may indicate the time (T0) at which the first time slot in the mmW link begins. This point may be indicated relative to the end of the NDPA frame. In one example, the slot start point T0 may be indicated to be a SIFS or any other IFS occurring after the end of the NDPA frame.

[0140] The start time slot subfield 1222 may indicate which time slot will be the time slot in which the first NDP PPDU may be transmitted. In one example, the AP may choose to postpone transmission of the NDP PPDU for one or more time slots starting at the first time slot and begin transmitting the first NDP PPDU at the start time slot.

[0141] Furthermore, in one embodiment, the mmW-SIG field (as described in FIG. 8 above) may include a time slot information subfield as described in Table 5 below, in addition to the subfields listed in Table 4.

[0142] [Table 5]

[0143] Figure 13 shows an example frame exchange sequence for a time slot-based beam training procedure. As shown in Figure 13, in one embodiment, one AP and one or more non-AP STAs can participate in one or more beam training sessions as shown in Figure 13. The AP 1302 can participate as the initiator of the beam training session, and the non-AP STAs 1304 and 1306 can participate as responders of the beam training session. The control frame of the beam training session can be sent over a sub-7 GHz link, and the beam training NDP PPDU can be sent over a mmW link.

[0144] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP can transmit an NDPA on one or more of the sub-7 GHz band links in a TXOP immediately claimed by this AP. The NDPA can be transmitted in a UHR PPDU or any legacy PPDU. The bandwidth of the PPDU carrying the NDPA can be indicated in the SIG field of the PPDU carrying the NDPA. The bandwidth indicated in the common info field, special STA Info field(s), or the STA Info field of the NDPA refers to the bandwidth of the beam training NDP PPDU that will be transmitted immediately after the NDPA.

[0145] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP can switch to one or more links in the mmW band and transmit a beam training NDP PPDU. The AP can follow a time slot-based structure where the transmission of the beam training NDP PPDU occurs only within the time slot.

[0146] In one embodiment, the AP initiating the beam training session and the holder of the current TXOP can indicate the time point at which the first time slot begins (T0) in the Slot Start subfield of the Common Info field in the NDPA frame immediately prior to transmitting the beam training NDP. In one example, the T0 point can be indicated as a 1 SIFS after the end of the NDPA frame.

[0147] In one embodiment, an AP initiating a beam training session and being the holder of the current TXOP can choose to postpone transmission in the first time slot of a set of time slots that will be used to send the beam training NDP PPDU.

[0148] In one embodiment, the AP can choose to send one or more NDP PPDUs in the same time slot. NDP PPDUs transmitted within a time slot can be separated from each other by SIFS or any IFS. The NDP PPDU can cover the entire bandwidth of the mmW link, as indicated in the common info field, the special STA Info field(s), or the STA Info field of the NDPA. The NDP PPDU can have punctured subchannels within the PPDU bandwidth, which can also be indicated in the NDPA. One or more NDP PPDUs can be transmitted in each available sector, with each NDP identified by an NDP ID, a sector ID, and an antenna ID. The number of transmitted NDP PPDUs can be equal to or greater than the number of sectors. The AP STA sweeps to the next sector and transmits the corresponding NDP(s) intended for transmission in this sector. Transmission of an NDP PPDU intended for one transmitting sector can occur in one or more time slots. Each NDP may be transmitted at a transmit power equal to the NDP Tx power as indicated in the NDPA immediately preceding the NDP transmission. The number of LTFs in each NDP PPDU may be indicated in the NDPA and may be greater than or equal to the largest number of receive sectors / beams supported by non-AP STAs participating in the beam training session.

[0149] In one embodiment, the AP initiating the beam training session and being the holder of the current TXOP can switch back to the sub-7 GHz link and transmit a BFRP or any other trigger or control frame designed to trigger feedback transmissions from non-AP STAs in the uplink. The transmission of the trigger frame to solicit feedback can start at the ending boundary of the last time slot of the group of time slots used for the mmW beam training session.

[0150] In one embodiment, one or more non-AP STAs may participate in a beam training session as responders such that each non-AP STA may be addressed by one or more STA Info fields in the NDPA sent from the AP that is the initiator of the beam training session.

[0151] In one embodiment, a non-AP STA receives an NDPA sent by an AP over a sub-7 GHz link, parses the Dialogue Token field and / or the Common Info field and / or the Special STA Info field(s) to detect whether the NDPA is initiating a beam training session, and collects all information signaled in the aforementioned fields to prepare for the beam training session and to set up the time structure in which the time slots for the beam training session are defined and signaled in the NDPA frame.

[0152] In one embodiment, a non-AP STA may parse the STA Info list, searching for a STA Info field addressed to itself by examining AID 11. If the non-AP STA AID matches one or more STA Info fields in the STA Info list, the non-AP may parse the STA Info field(s) and begin preparing for a beam training session. Otherwise, if the non-AP STA AID does not match any of the AIDs 11 of the STA Info fields in the STA Info list, the non-AP STA may stop decoding the NDPA and may enter doze mode after setting its NAV counter(s).

[0153] In one embodiment, if a non-AP STA is addressed in the STA info list of an NDPA sent immediately over a sub-7 GHz link, the non-AP STA may switch to the mmW link(s) and prepare to receive NDP PPDUs that may be sent over the mmW link(s) as indicated in the STA Info field. The non-AP STA may start a counter at point T0, which indicates the starting boundary of the first time slot. The non-AP may begin receiving NDP PPDUs at the starting boundary of the start time slot, which indicates the time slot in which the first NDP PPDU transmission may occur. If the AP chooses to postpone NDP PPDU transmission in the first time slot(s) starting at T0, the start time slot may be different from the first time slot.

[0154] In one embodiment, a non-AP STA may switch its receive beam for each LTF symbol or group of LTF symbols included in a received NDP PPDU transmitted in one of the AP's transmit sectors / beams in one of the time slots of the time structure. The non-AP may then measure the SNR, RSSI, or any other physical measurement of the received LTF to represent the strength or quality of the received signal. The non-AP STA may also measure the average SNR, average RSSI, or average of any other physical measurement of the received group of LTFs to represent the strength or quality of the received signal. The non-AP STA may average measurements over multiple NDP PPDUs if the AP transmits two or more NDP PPDUs in the same sector / beam in the same time slot or across multiple time slots. By performing this reception procedure, each non-AP may have a measure of the signal strength or signal quality of each transmit beam and receive beam pair.

[0155] In one embodiment, a non-AP STA may prepare a beam training report and send it back to the AP in response to a beam training trigger frame sent to solicit the beam training report. Both the beam training trigger frame and the solicited beam training report may be sent over the sub-7 GHz link(s).

[0156] 14 is a flowchart illustrating an exemplary time slot-based beam training procedure. In one embodiment, the beam training procedure described above can be illustrated by the flowchart shown in FIG. 14, taking into account the time structure defined by the time slots used to manage the transmission of NDP PPDUs.

[0157] At 1402, a non-AP STA may receive an NDPA from an AP over a sub-7 GHz link.

[0158] At 1404, the non-AP STA may identify the NDPA variant as the mmW beam training variant.

[0159] At 1406, the non-AP STA may locate the STA Info fields addressed to it by examining the AID11 field of each STA Info field in the STA Info list of the NDPA.

[0160] At 1408, the non-AP STA determines whether the non-STA AID matches any of the AIDs 11 in the STA info field in the STA Info list. At 1410, if the AID 11 does not match, the non-AP STA may stop decoding the NDPA, set one or more NAV counters, and enter doze mode.

[0161] If AID11 matches, at 1412, the non-AP STA can decode one or more STA Info fields with the matching AID11 and decode the dialog token field, and / or the special STA info field, and / or the common Info field.

[0162] At 1414, the non-AP STA can parse the signaling information, prepare for the beam training session, switch to one or more mmW links, and set up a time structure based on a start time (T0), a time slot duration, a number of slots, and a start time slot.

[0163] At 1416, the non-AP STA may receive the NDP PPDU sent in the starting time slot and the subsequent time slots.

[0164] At 1418, the non-AP STA may switch its receive beam for each LTF symbol or group of LTF symbols included in a received NDP PPDU transmitted in one of the AP's transmit sectors / beams. The non-AP may then measure the SNR, RSSI, or any other physical measurement of the received LTF to represent the strength or quality of the received signal. The non-AP STA may also measure the average SNR, average RSSI, or average of any other physical measurement of the received group of LTFs to represent the strength or quality of the received signal. The non-AP STA may average measurements over multiple NDP PPDUs if the AP transmits more than one NDP PPDU in the same sector / beam. By performing this receive procedure, each non-AP should have a measure of the signal strength or signal quality of each pair of transmit and receive beams.

[0165] At 1420, the non-AP STA can switch back to the sub-7 GHz link to receive the beam training trigger frame and send a beam training feedback report back to the AP.

[0166] In one embodiment, the beam training methods and procedures employed to identify the best transmit and receive beam pairs for downlink operation (transmissions from AP STAs to non-AP STAs) as described above may be used reciprocally as preferred beam pairs for uplink transmissions (transmissions from non-AP STAs to AP STAs). The best transmit beam for downlink transmissions from the AP to non-AP STAs may be used as the best receive beam for uplink transmissions from non-AP STAs to the AP, and the best receive beam for downlink transmissions from the AP to non-AP STAs may be used as the best transmit beam for uplink transmissions from non-AP STAs to AP STAs.

[0167] In one embodiment, beam failure may be triggered by an event when the number of consecutive ACKs or Block ACKs sent to the same STA that are not received by the sender of the PPDU is equal to or greater than N, where N is a system parameter. N may be conveyed in a beacon or other management frame. For example, if the sender of the PPDU, an AP, does not receive an ACK or Block ACK for N consecutive PPDU transmissions to the same STA, the AP may determine that there is a beam failure between the AP and the receiving STA.

[0168] In one embodiment, after detecting a beam failure, an AP STA can initiate a beam recovery procedure with one or more non-AP STAs. In one example, the AP can detect a beam failure by observing the bit error rate (BER) or packet error rate (PER) and trigger a beam failure event when the BER or PER exceeds a given value. The beam recovery procedure can be initiated pairwise with one non-AP STA at a time, or it can be initiated simultaneously with two or more non-AP STAs. In another embodiment, the beam recovery procedure can be initiated by the non-AP STA(s).

[0169] In one embodiment, a non-AP STA can continuously report a physical layer measurement, such as the RSSI or SNR, of a data packet sent via a given transmit beam and receive beam pair. The AP STA can then declare a beam failure if this measurement falls below a given threshold. The AP can also count the number of times a beam failure event is detected and initiate a beam recovery procedure if the number of beam failures exceeds a preset value. The RSSI or SNR threshold at which a beam failure event is detected can be set as a static value announced in a beacon frame or any other management frame. The RSSI or SNR threshold at which a beam failure event is detected can also be dynamically set using an NDPA frame or any control frame that initially initiates beam training. The number of beam failure events at which a beam recovery procedure should be initiated can be set as a static value announced in a beacon frame or any other management frame. The number of beam failure events at which a beam recovery procedure should be initiated can also be dynamically set using an NDPA frame or any control frame that initially initiates beam training.

[0170] In one embodiment, an information element named beam recovery element may be added to a beacon frame, an association request frame, an association response frame, a reassociation request frame, a reassociation response frame, a probe request frame, a probe response frame, or any other management frame used to manage operation in a BSS or multi-AP as an example indication in a beacon frame in Table 6 below.

[0171] 15 is an example beam recovery element format 1500. In one embodiment, the beam recovery element may be used to statically configure a beam recovery procedure. As shown in FIG. 15, the beam recovery element may include an element ID field 1502, a length field 1504, an element ID extension field 1506, and a beam recovery control field 1508.

[0172] 16 is an example beam recovery control field format 1600 as shown in 1508. As shown in FIG. 16, the beam recovery control field may include a beam failure SNR threshold subfield 1602, a beam failure maximum number subfield 1604, a beam failure timer subfield 1606, and a reserved subfield 1608.

[0173] The beam impairment SNR threshold subfield 1602 may signal the SNR level at which a beam may be considered impaired. An example encoding of this subfield is shown in Table 7 below.

[0174] The Beam Failure Max Number subfield 1604 may signal the number of beam failure events that will cause the beam to be considered unreliable and for the STA to initiate a beam recovery procedure. An example encoding of this subfield is shown in Table 8 below.

[0175] The beam failure timer subfield 1606 may signal a timer initial value that is initialized and begins counting down when a beam failure event is detected, and if the timer reaches 0 before another beam failure occurs, the counter that counts the number of beam failure events may be reset to 0.

[0176] [Table 6]

[0177] [Table 7]

[0178] [Table 8]

[0179] In one embodiment, the NDPA employed to initiate a beam training session can also signal the configuration of the beam recovery procedure.

[0180] 17 is an example common info field frame format 1700 for dynamic configuration of beam recovery procedures. The common info field frame for dynamic configuration of beam recovery procedures can include a Ver subfield 1702, a Dialogue Token subfield 1704, a BW subfield 1706, a Channel Puncturing Info subfield 1708, an Nt subfield 1710, an Nr subfield 1712, a Number of Tx Sectors subfield 1714, a Beam Failure SNR Threshold 1716, a Max Number of Beam Failures 1718, a Beam Failure Timer 1720, a Number of LTFs in Each NDP subfield 1722, and an NDP Tx Power subfield 1724.

[0181] As shown in FIG. 17, the common info field, the special STA info field(s), or the STA info field(s) may include one or more of the following subfields, beam failure SNR threshold, beam failure maximum number, and beam failure timer, which may be used to dynamically configure the beam recovery procedure.

[0182] In one embodiment, each time a beam failure occurs, the AP or non-AP STA may increment a counter of the number of beam failure events by 1 and reset a beam failure timer. If the beam failure timer reaches 0 before a new beam failure is detected, the beam failure counter is reset to 0. If the beam failure counter reaches the maximum number of beam failures, the AP initiates a beam recovery procedure. Figure 18 shows an exemplary beam failure detection procedure.

[0183] In one embodiment, a beam recovery procedure may be initiated by an AP STA after detecting a beam failure. The beam recovery procedure may begin by sending an mmW beam training NDPA over the sub-7 GHz link, followed by a SIFS followed by a series of NDP PPDUs transmitted over the mmW link, which may follow the same procedure employed for initial beam training. The AP may then send a trigger frame to solicit a beam training report over the sub-7 GHz link.

[0184] In one embodiment, the NDPA sent to initiate beam recovery may contain a STA Info field addressed to the non-AP STA, whose beam connecting it to the AP is to be declared beam impaired. The NDPA may also contain STA Info fields for other non-STAs, whether these are in initial beam training or whose beams are to be declared beam impaired.

[0185] In one embodiment, a non-AP STA can send a frame indicating beam failure on a lower bandwidth link to the AP after beam failure is triggered at the MAC layer of the non-AP STA. This signal can then be carried in a control frame, such as an ACK or block frame, or the A-control field of a management frame or data frame.

[0186] FIG. 18 is a flowchart illustrating an exemplary beam obstruction detection procedure.

[0187] At 1802, the non-AP STA may measure the SNR of the LTF in the preamble of the received data packet.

[0188] At 1804, the non-AP STA may determine whether the measured SNR is less than the beam obstruction SNR threshold. If the measured SNR is greater than or equal to the beam obstruction SNR threshold, the non-AP STA may return to 1804 and continue measuring the SNR.

[0189] If the measured SNR is less than the beam failure SNR threshold, at 1806, the non-AP STA increments the beam failure counter by 1, resets the beam failure timer, starts a timer on the beam failure timer, and can receive the next packet.

[0190] At 1808, the non-AP STA may determine whether the beam failure timer reaches 0 before a new beam failure event is detected. If the beam failure timer has not reached 0, the non-AP STA returns to 1806 and increments the beam failure counter by 1 if another measured SNR is less than the beam failure SNR threshold.

[0191] At 1810, if the beam failure timer reaches 0, the non-AP STA may reset the beam failure counter and reset the beam failure timer.

[0192] At 1812, the non-AP STA may determine whether the beam failure counter reaches the beam failure maximum number. If the beam failure counter reaches the beam failure maximum number, the non-AP STA may begin a beam recovery procedure at 1814. If the beam failure counter has not reached the beam failure maximum number, the non-AP STA may return to 1802.

[0193] 19 is a flowchart illustrating an exemplary beam training procedure 1900. In one embodiment, the beam training procedure described above may be illustrated by the flowchart shown in FIG.

[0194] At 1902, a non-AP STA may receive an NDPA over the STA's sub-7 GHz link. The NDPA may include information for initiating a millimeter wave (mmW) beam training process. At 1904, the non-AP STA may determine that at least one STA info field has an AID subfield in the NDPA frame that matches an association ID (AID) associated with the STA. At 1906, the non-AP STA may determine STA subfield information corresponding to an mmW beam training session based on the matching AID. At 1908, the non-AP STA may receive one or more NDP PPDUs over the mmW link based on the STA subfield information. At 1910, the non-AP STA may transmit a beam training feedback report over the sub-7 GHz link based on the one or more NDP PPDUs received over the mmW link.

[0195] Although the features and elements of the present invention are described in specific combinations in preferred embodiments, each feature or element may be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention.

[0196] While the solutions described herein consider 802.11-specific protocols, it should be understood that the solutions described herein are not limited to this scenario and are applicable to other wireless systems. SIFS is used to denote various inter-frame intervals in the design and procedure examples, but all other inter-frame intervals, such as RIFS, AIFS, DIFS, or other agreed-upon time intervals, may be applied in the same solution. Sub-7 GHz links / bands are used to refer to links in MLO systems where control / management frames may be transmitted for mmW links / bands, but it may be replaced by more general terms such as lower frequency links / bands.

[0197] A first field / subfield / element / subelement may be defined in a second field / subfield / element / subelement / frame, but the first field / subfield / element / subelement may be carried in other fields / subfields / elements / subelements / frames to indicate the same information.

[0198] Although the above describes an NDPA frame transmitted over a sub-7 GHz link to schedule beam training in an mmW link, the NDPA frame may be replaced or renamed by other management or control frames with similar information and signaling as disclosed herein.

[0199] Although the above describes NDP PPDUs / frames transmitted over mmW links, the NDP PPDUs / frames may be replaced or renamed by other management or control frames with similar design and signaling as disclosed herein.

[0200] The long training field (LTF) can be any type of predefined sequence that is known at both the transmitter and receiver sides.

[0201] Although features and elements have been described above in particular combinations, those skilled in the art will appreciate that each feature or element may be used alone or in any combination with the other features and elements. Furthermore, the methods described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. 1. A method implemented by a station (STA), comprising: receiving a Null Data Packet (NDP) Announcement (NDPA) frame on a sub-7 GHz link of the STA, the NDPA including information for initiating a millimeter wave (mmW) beam training process; determining that at least one STA Info field included in the NDPA frame includes an Association ID (AID) subfield that matches an AID associated with the STA; receiving one or more NDP physical layer protocol data units (PPDUs) over an mmW link based on information contained in the STA Info field; transmitting, over the sub-7 GHz link, a beam training feedback report based on the one or more NDP PPDUs received over the mmW link; A method for providing

2. The method of claim 1 , wherein the NDPA includes a Common Info field.

3. 3. The method of claim 2, wherein the Common Info field includes at least one of a Ver subfield, a Dialogue Token Number subfield, a STA Info Size subfield, a BW subfield, a Channel Puncturing Info subfield, an Nt subfield, an Nr subfield, a Number of Tx Sectors subfield, a Number of Rx Sectors subfield, a Number of NDPs subfield, a Number of LTFs in each NDP subfield, or an NDP Tx Power subfield.

4. 2. The method of claim 1, wherein the STA Info field includes at least one of an AID11 subfield, a Preferred Tx Sector ID subfield, a Preferred Rx Sector ID subfield, a BW subfield, an mmW Link ID subfield, an SNR Report Required subfield, or an Interference SNR Threshold subfield.

5. 2. The method of claim 1, wherein the one or more NDP PPDUs include at least one of an mmW U-SIG field or an mmW-SIG field.

6. 6. The method of claim 5, wherein the mmW U-SIG field includes at least one of a PHY version subfield, a bandwidth subfield, an mmW band subfield, a direction subfield, a BSS color subfield, a TXOP subfield, a PPDU type subfield, a channel puncturing info subfield, an mmW-SIG MCS subfield, or an mmW-SIG symbol number subfield.

7. The method of claim 5 , wherein the mmW-SIG field includes at least one of a sector number subfield, an NDP ID subfield, a sector ID subfield, an antenna ID subfield, an LTF size subfield, or an LTF number subfield.

8. A station (STA), receiving a Null Data Packet (NDP) Announcement (NDPA) frame on the sub-7 GHz link of the STA, the NDPA including information for initiating a millimeter wave (mmW) beam training process; determining that at least one STA Info field included in the NDPA frame has an Association ID (AID) subfield that matches an AID associated with the STA; receiving one or more NDP physical layer protocol data units (PPDUs) over an mmW link based on information contained in the STA Info field; and transmitting, over the sub-7 GHz link, a beam training feedback report based on the one or more NDP PPDUs received over the mmW link. one or more transceivers and a processor configured to A station (STA) equipped with:

9. The STA of claim 8 , wherein the NDPA includes a Common Info field.

10. 10. The STA of claim 9, wherein the Common Info field includes at least one of a Ver subfield, a Dialogue Token Number subfield, a STA Info Size subfield, a BW subfield, a Channel Puncturing Info subfield, an Nt subfield, an Nr subfield, a Number of Tx Sectors subfield, a Number of Rx Sectors subfield, a Number of NDPs subfield, a Number of LTFs in each NDP subfield, or an NDP Tx Power subfield.

11. 2. The STA of claim 1, wherein the STA Info field includes at least one of an AID11 subfield, a Preferred Tx Sector ID subfield, a Preferred Rx Sector ID subfield, a BW subfield, an mmW Link ID subfield, an SNR Report Required subfield, or an Interference SNR Threshold subfield.

12. The STA of claim 10, wherein the one or more NDP PPDUs include at least one of an mmW U-SIG field or an mmW-SIG field.

13. 13. The STA of claim 12, wherein the mmW U-SIG field includes at least one of a PHY version subfield, a bandwidth subfield, an mmW band subfield, a direction subfield, a BSS color subfield, a TXOP subfield, a PPDU type subfield, a channel puncturing info subfield, an mmW-SIG MCS subfield, or an mmW-SIG symbol number subfield.

14. The STA of claim 12, wherein the mmW-SIG field includes at least one of a sector number subfield, an NDP ID subfield, a sector ID subfield, an antenna ID subfield, an LTF size subfield, or an LTF number subfield.

Images