Method for realizing multi-link millimeter wave beam training

Abstract

A method for implementing multi-link millimeter wave (mmW) beam training is provided herein. A method performed by a station (STA) may include receiving a null data packet (NDP) advertisement (NDPA) frame on a link of the STA below 7 GHz, where the NDPA includes information for initiating a millimeter wave (mmW) beam training procedure; determining that at least one STA information field included in the NDPA frame includes an association ID (AID) subfield matching an 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 information field; and transmitting a beam training feedback report on the basis of the one or more NDP PPDUs received on the mmW link on a link of 7 GHz or less.

Description

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 427,006, filed on November 21, 2022, the content of which is incorporated herein by reference. Background Art

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

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

[0004] In 802.11n, high - throughput (HT) STAs can also communicate using 40 - MHz - wide channels. This is achieved by combining the 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 channels that are 20 MHz, 40 MHz, 80 MHz, and 160 MHz wide. 40 MHz channels and 80 MHz channels are formed by combining consecutive 20 MHz channels similar to those in 802.11n described above. A 160 MHz channel can be formed by combining eight consecutive 20 MHz channels or by combining two non - consecutive 80 MHz channels (which can also be referred to as an 80 + 80 configuration). For the 80 + 80 configuration, after channel coding, the data is passed through a segment parser that splits the data into two streams. The inverse discrete Fourier transform (IDFT) operation and time - domain processing are performed separately on each stream. Then, the streams are mapped to two channels and the data is transmitted. At the receiver, the mechanism is reversed and the combined data is sent to the MAC.

[0006] To improve spectral efficiency, 802.11ac has introduced the concept of downlink multi - user MIMO (MU - MIMO) transmission to multiple STAs within the time frame of the same symbol (e.g., during a downlink OFDM symbol). The potential of using downlink MU - MIMO is also currently being considered for 802.11ah. Notably, since downlink MU - MIMO (as used in 802.11ac) uses the same symbol timing for multiple STAs, interference to the waveform transmissions of multiple STAs is not an issue. However, all STAs involved in MU - MIMO transmission using an AP must use the same channel or frequency band, which limits the operating bandwidth to the minimum channel bandwidth supported by the STAs included in the MU - MIMO transmission with the AP. Summary of the Invention

[0007] Methods for implementing multi - link millimeter - wave (mmW) beam training are provided herein. A method performed by a station (STA) can 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 information field included in the NDPA frame includes an AID sub - field 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 information field; and transmitting a beam training feedback report on the sub - 7 GHz link based on the one or more NDP PPDUs received on the mmW link.

[0008] The NDPA may include a common information field. The common information field may include at least one of a Ver sub-field, a conversation token number sub-field, an STA information size sub-field, a BW sub-field, a channel puncturing information sub-field, an Nt sub-field, an Nr sub-field, a Tx sector quantity sub-field, an Rx sector quantity sub-field, an NDP quantity sub-field, an LTF quantity sub-field in each NDP, or an NDP Tx power sub-field.

[0009] The STA information field may include at least one of an AID11 sub-field, a preferred Tx sector ID sub-field, a preferred Rx sector ID sub-field, a BW sub-field, an mmW link ID sub-field, a need SNR report sub-field, or a blocking SNR threshold sub-field.

[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 sub-field, a bandwidth sub-field, an mmW frequency band sub-field, a direction sub-field, a BSS color sub-field, a TXOP sub-field, a PPDU type sub-field, a channel puncturing information sub-field, an mmW-SIG MCS sub-field, or an mmW-SIG symbol quantity sub-field. The mmW-SIG field may include at least one of a sector quantity sub-field, an NDP ID sub-field, a sector ID sub-field, an antenna ID sub-field, an LTF size sub-field, or an LTF quantity sub-field. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more detailed understanding can be obtained from the following description given by way of example in conjunction with the drawings, in which like reference numerals in the figures indicate like elements, and in which: Figure 1A is a system diagram illustrating an example communication system in which one or more embodiments disclosed herein can be implemented; Figure 1B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that can be used within the Figure 1A illustrated communication system according to one embodiment; Figure 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that can be used within the Figure 1A illustrated communication system according to one embodiment; Figure 1D is a system diagram illustrating a further example RAN and a further example CN that can be used within the Figure 1A illustrated communication system according to one embodiment; Figure 2is a diagram illustrating an exemplary Null Data Packet (NDP) Announcement (NDPA) frame format; Figure 3 is a diagram illustrating an exemplary Probe Dialog Token field format in an NDPA frame; Figure 4 is a diagram illustrating an exemplary STA Information field format in an Extremely High Throughput (EHT) NDPA frame; Figure 5 is a diagram illustrating an exemplary NDP frame format for Ultra-High Reliability (UHR) and mmW support; Figure 6 is a diagram illustrating a first exemplary Common Information field format in a UHR mmW NDPA frame; Figure 7 is a diagram illustrating an exemplary STA Information field format in a UHR mmW NDPA frame; Figure 8 is a diagram illustrating a first exemplary mmW Beam Training NDP frame format; Figure 9 is a diagram illustrating a second exemplary mmW Beam Training NDP frame format; Figure 10 is a diagram illustrating an exemplary frame exchange sequence for a beam training process; Figure 11 is a diagram illustrating a flowchart of an exemplary beam training process; Figure 12 is a diagram illustrating a first exemplary Common Information field format in a UHR mmW NDPA frame; Figure 13 is a diagram illustrating an exemplary frame exchange sequence for a slot-based beam training process; Figure 14 is a diagram illustrating a flowchart of an exemplary slot-based beam training process; Figure 15 is a diagram illustrating an exemplary Beam Recovery Element format; Figure 16 is a diagram illustrating an exemplary Beam Recovery Control field in a Beam Recovery Element; Figure 17 is a diagram illustrating an exemplary Common Information field for dynamic configuration of a beam recovery process; Figure 18 is a diagram illustrating a flowchart of an exemplary beam failure detection process; and Figure 19 is a diagram illustrating a flowchart of an exemplary beam training process. Detailed Description

[0012] Figure 1AFIG. is a diagram illustrating an example communication system 100 in which one or more of the disclosed embodiments may be implemented. The communication system 100 may be a multi-access system that provides content (such as voice, data, video, messaging, broadcasts, etc.) to a plurality of wireless users. The communication system 100 may enable the plurality of wireless users to access such content by sharing 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 unique word DFT-spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), etc.

[0013] As Figure 1A shown, the communication 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 appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the 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 one of which may be referred to as a station (STA)) may be configured to transmit and / or receive wireless signals and may include 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 smart phone, a laptop computer, a netbook, a personal computer, a wireless sensor, a hot spot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, 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 automation processing chain scenario), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any one of the WTRUs 102a, 102b, 102c, 102d may be interchangeably referred to as a UE.

[0014] The communication system 100 may further include base station 114a and / or base station 114b. Each of base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as CN 106, Internet 110, and / or other networks 112. By way of example, base stations 114a, 114b may be base transceiver stations (BTSs), NodeBs, eNode Bs (eNBs), home NodeBs, home eNode Bs, next-generation NodeBs (such as gNode Bs (gNBs)), New Radio (NR) NodeBs, site controllers, access points (APs), wireless routers, etc. Although base stations 114a, 114b are each depicted as a single element, it will be appreciated that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0015] Base station 114a may be part of RAN 104, which may further include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of a particular geographical area for wireless services, 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 base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may use multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0016] Base stations 114a, 114b may communicate with one or more of WTRUs 102a, 102b, 102c, 102d via air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). Air interface 116 may be established using any suitable radio access technology (RAT).

[0017] More specifically, as noted above, the communication system 100 can be a multi-access system and can employ one or more channel access schemes, such as, CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a in the RAN 104, and the WTRUs 102a, 102b, 102c can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA can include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed Uplink (UL) Packet Access (HSUPA).

[0018] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can use Long-Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro) to establish the air interface 116.

[0019] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement radio technologies such as NR radio access, which can use NR to establish the air interface 116.

[0020] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c can implement LTE radio access and NR radio access together, for example, using the Dual Connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c can be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0021] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), 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 Rate for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0022] Figure 1A The base station 114b in may be, for example, a wireless router, a home node B, a home eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connection in a local area such as a commercial venue, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement radio technologies 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 radio technologies such as IEEE 802.15 to establish a Wireless Personal Area Network (WPAN). In yet another 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 a pico cell or a femto cell. As Figure 1A shown, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106.

[0023] The RAN 104 may communicate with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different Quality of Service (QoS) requirements such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, location-based services, prepaid calling, Internet connectivity, video distribution, etc. and / or perform advanced security functions such as user authentication. Although Figure 1Ais not shown, but it will be appreciated that RAN 104 and / or CN 106 may communicate directly or indirectly with other RANs that employ the same RAT or a different RAT than RAN 104. For example, in addition to being connected to RAN 104 which may utilize NR radio technology, CN 106 may also communicate with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0024] CN 106 may also act as a gateway for 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 that provides 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 the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the 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 that is connected to one or more RANs, which may employ the same RAT or a different RAT than RAN 104.

[0025] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication 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, Figure 1A the illustrated WTRU 102c may be configured to communicate with a base station 114a that may employ a cellular-based radio technology and a base station 114b that may employ IEEE 802 radio technology.

[0026] Figure 1B is a system diagram illustrating an example WTRU 102. As Figure 1B shown, the WTRU 102 may include a processor 118, a transceiver 120, transmit / receive elements 122, a speaker / microphone 124, a keyboard 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other peripheral devices 138, etc. It will be appreciated that the WTRU 102 may include any sub-combination of the above elements while remaining consistent with the embodiments.

[0027] The processor 118 can be a general-purpose processor, a dedicated 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), any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other function that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to a transceiver 120, which can be coupled to a transmit / receive element 122. Although Figure 1B the processor 118 and the transceiver 120 are depicted as separate components, it will be appreciated that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0028] The transmit / receive element 122 can be configured to transmit signals to a base station (e.g., base station 114a) or receive signals from a base station via an air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can be a transmitter / detector configured to transmit and / or receive signals such as IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive both RF and optical signals. It will be appreciated that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0029] Although the transmit / receive element 122 is depicted as a single element in Figure 1B the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via the air interface 116.

[0030] The transceiver 120 can be configured to modulate the signals to be transmitted by the transmit / receive element 122 and demodulate the signals received by the transmit / receive element 122. As noted above, the WTRU 102 can have multi-mode capabilities. Thus, for example, the transceiver 120 can include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs (such as NR and IEEE 802.11).

[0031] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keyboard 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), and may receive user input data from them. The processor 118 may also output user data to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128. Additionally, the processor 118 may access information from any type of suitable memory (such as non-removable memory 130 and / or removable memory 132), and store data in that memory. 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 a memory that is not physically located on the WTRU 102 (such as on a server or a home computer (not shown)), and store data in that memory.

[0032] The processor 118 may receive power from a power supply 134, and may be configured to distribute and / or control the power to other components in the WTRU 102. The power supply 134 may be any suitable device for powering the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0033] 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) about the current location of the WTRU 102. In addition to or instead of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) via an air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with the embodiments.

[0034] The processor 118 can be further coupled to other peripheral devices 138, which can include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connections. For example, the peripheral devices 138 can 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, modules, a frequency modulation (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 peripheral devices 138 can include one or more sensors, which can be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geographical location sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, and so on.

[0035] The WTRU 102 can include a full-duplex radio, for which the transmission and reception of some or all signals (e.g., associated with a particular subframe for both UL (e.g., for transmission) and DL (e.g., for reception)) can be concurrent and / or simultaneous. The full-duplex radio can include an interference management unit to reduce and / or substantially eliminate self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WTRU 102 can include a half-duplex radio, for which the transmission and reception of some or all signals (e.g., associated with a particular subframe for UL (e.g., for transmission) or DL (e.g., for reception)).

[0036] Figure 1C is a system diagram illustrating a RAN 104 and a CN 106 according to one embodiment. As noted above, the RAN 104 employs E-UTRA radio technology to communicate with the WTRU 102a, 102b, 102c via the air interface 116. The RAN 104 can also communicate with the CN 106.

[0037] The RAN 104 may include eNode-Bs 160a, 160b, 160c, although it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with the embodiments. Each of the eNode-Bs 160a, 160b, 160c may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may transmit wireless signals to and / or receive wireless signals from the WTRU 102a using multiple antennas.

[0038] Each of the eNode-Bs 160a, 160b, 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 UL and / or DL, etc. As Figure 1C shown, the eNode-Bs 160a, 160b, 160c may communicate with each other via the X2 interface.

[0039] Figure 1C The illustrated CN 106 may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (PGW) 166. Although the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0040] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via the 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 the initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide control plane functions for handover between the RAN 104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0041] The SGW 164 can be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 can typically route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 can perform other functions such as anchoring the user plane during handover between eNode Bs, 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.

[0042] The SGW 164 can be connected to the PGW 166, which can provide the WTRUs 102a, 102b, 102c with access to a packet switched network (such as the Internet 110) to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0043] The CN 106 can facilitate communication with other networks. For example, the CN 106 can provide the WTRUs 102a, 102b, 102c with access to a circuit switched network (such as the PSTN 108) to facilitate communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, the CN 106 can include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) or can communicate with the IP gateway, which serves as an interface between the CN 106 and the PSTN 108. Additionally, the CN 106 can provide the WTRUs 102a, 102b, 102c with access to other networks 112, which can include other wired and / or wireless networks owned and / or operated by other service providers.

[0044] Although the WTRU is Figures 1A to 1D described as a wireless terminal, it is envisioned that in certain representative embodiments, such a terminal can use (e.g., temporarily or permanently) a wired communication interface with the communication network.

[0045] In a representative embodiment, the other network 112 can be a WLAN.

[0046] In an infrastructure basic service set (BSS) mode, a WLAN can have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP can have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic originating outside the BSS and destined for an STA can reach the STA through the AP and can be delivered to the STA. Traffic from an STA to a destination outside the BSS can be sent to the AP for delivery to the corresponding destination. Traffic between STAs within the BSS can be sent through the AP. For example, the source STA can send the traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer traffic. Peer traffic can be sent between the source and destination STAs (e.g., directly between them) using direct link setup (DLS). In some representative embodiments, DLS can use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode can not have an AP, and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode can sometimes be referred to in this document as an "ad-hoc" communication mode.

[0047] When using an 802.11ac infrastructure operation mode or a similar operation mode, the AP can transmit beacons on a fixed channel (such as the primary channel). The primary channel can be of a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel can be the operation 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. For CSMA / CA, STAs including the AP (e.g., each STA) 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. Only one STA (e.g., just one station) can transmit in a given BSS at any given time.

[0048] High throughput (HT) STAs can communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and an adjacent or non-adjacent 20 MHz channel to form a 40 MHz wide channel.

[0049] A very high throughput (VHT) STA can support channels that are 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide. 40 MHz and / or 80 MHz channels 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 (which can be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, the data can be passed through a segment parser that can divide the data into two streams. Inverse fast Fourier transform (IFFT) processing and time - domain processing can be done separately on each stream. The streams can be mapped to two 80 MHz channels, and the data can be transmitted by the STA that is performing the transmission. At the receiver of the STA that is performing the reception, the above operations for the 80+80 configuration can be reversed, and the combined data can be sent to the media access control (MAC).

[0050] The operation modes below 1 GHz are supported by 802.11af and 802.11ah. The channel operation bandwidth and carriers are reduced in 802.11af and 802.11ah as compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz bandwidth, 10 MHz bandwidth, and 20 MHz bandwidth in the TV white space (TVWS) spectrum, and 802.11ah supports 1 MHz bandwidth, 2 MHz bandwidth, 4 MHz bandwidth, 8 MHz bandwidth, and 16 MHz bandwidth 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 a macro - coverage area. MTC devices can have certain capabilities, for example, limited capabilities, including supporting (e.g., only supporting) certain and / or limited bandwidths. MTC devices can include a battery whose battery life is higher than a threshold (e.g., to maintain a very long battery life).

[0051] A WLAN system that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) includes a channel that can be designated as the primary channel. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or restricted by the STA that supports the minimum bandwidth operation mode among all STAs operating in the BSS. In the example of 802.11ah, for an STA that supports (e.g., only supports) the 1MHz mode (e.g., an MTC type device), the primary channel can be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or Network Allocation Vector (NAV) settings can depend on the state of the primary channel. If the primary channel is busy, for example, due to an STA (which only supports the 1MHz operation mode) transmitting to the AP, then all available frequency bands may be considered busy, even if most of the available frequency bands are still idle.

[0052] In the United States, the available frequency band that 802.11ah can use is from 902MHz to 928MHz. In Korea, the available frequency band is from 917.5MHz to 923.5MHz. In Japan, the available frequency band is from 916.5MHz to 927.5MHz. Depending on the country code, the total available bandwidth for 802.11ah is 6MHz to 26MHz.

[0053] Figure 1D FIG. is a system diagram illustrating RAN 104 and CN 106 according to an embodiment. As noted above, RAN104 can employ NR radio technology to communicate with WTRUs 102a, 102b, 102c via air interface 116. RAN 104 can also communicate with CN 106.

[0054] The RAN 104 may include gNBs 180a, 180b, 180c, although it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with the embodiments. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO techniques. For example, the gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to the WTRU 102a and / or receive wireless signals from the WTRU 102a. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation techniques. 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 unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) techniques. For example, the WTRU 102a may receive a coordinated transmission from the gNB 180a and the gNB 180b (and / or gNB 180c).

[0055] The WTRUs 102a, 102b, 102c may use transmissions associated with scalable numerology. For example, the OFDM symbol interval and / or the OFDM subcarrier interval may vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using various or scalable length subframes or transmission time intervals (TTIs) (e.g., containing different numbers of OFDM symbols and / or lasting for different lengths of absolute time).

[0056] gNBs 180a, 180b, 180c can be configured to communicate with WTRUs 102a, 102b, 102c in stand-alone configuration and / or non-stand-alone configuration. In stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c without accessing another RAN (e.g., such as eNode-Bs 160a, 160b, 160c). In stand-alone configuration, WTRUs 102a, 102b, 102c can utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor. In stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using signals in the unlicensed band. In non-stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN (such as eNode-Bs 160a, 160b, 160c). For example, WTRUs 102a, 102b, 102c can implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In non-stand-alone configuration, eNode-Bs 160a, 160b, 160c can act as the mobility anchor for WTRUs 102a, 102b, 102c, and gNBs 180a, 180b, 180c can provide additional coverage and / or throughput to serve WTRUs 102a, 102b, 102c.

[0057] Each of gNBs 180a, 180b, 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support for network slicing, networking between NR and E-UTRA for DC, routing of user plane data towards user plane functions (UPFs) 184a, 184b, routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, etc. As Figure 1D shown, gNBs 180a, 180b, 180c can communicate with each other via the Xn interface.

[0058] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possibly data networks (DN) 185a, 185b. Although the foregoing elements are depicted as part of CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0059] 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 the registration area, terminating non-access stratum (NAS) signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize the CN support for the WTRUs 102a, 102b, 102c based on the type of service utilized by the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services that rely on ultra-reliable low latency (URLLC) access, services that rely on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 182a, 182b may provide control plane functions for handover 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 WiFi.

[0060] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via an N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the traffic routing through the UPF 184a, 182b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0061] UPF 184a and 184b can be connected to one or more of gNBs 180a, 180b, 180c in RAN 104 via the N3 interface. These gNBs can provide access to a packet switched network (such as the Internet 110) to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices. UPF 184a and 184b can perform other functions such as routing and forwarding packets, implementing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0062] CN 106 can facilitate communication with other networks. For example, CN 106 can include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) or can communicate with such an IP gateway that serves as an interface between CN 106 and the PSTN 108. Additionally, CN 106 can provide access to other networks 112 to WTRU 102a, 102b, 102c. These other networks 112 can include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRU 102a, 102b, 102c can be connected to local DNs 185a, 185b via the N3 interface to UPF 184a, 184b and the N6 interface between UPF 184a, 184b and DNs 185a, 185b.

[0063] In view of Figures 1A to 1D and Figures 1A to 1D the corresponding descriptions, one or more or all of the functions described in the text regarding one or more of the following can be performed by one or more emulation devices (not shown): WTRU 102a to 102d, base stations 114a to 114b, eNode-Bs 160a to 160c, MME 162, SGW 164, PGW 166, gNBs 180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DNs 185a to 185b, and / or any other device(s) described herein. The emulation device(s) can be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation device(s) can be used to test other devices and / or simulate network and / or WTRU functionality.

[0064] Emulation devices can be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more emulation devices can perform one or more or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more emulation devices can perform one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. Emulation devices can be directly coupled to another device for testing purposes and / or perform tests using over-the-air wireless communication.

[0065] One or more emulation devices can perform one or more or all functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, emulation devices can be used to test test scenarios in a laboratory and / or non-deployed (e.g., test) wired and / or wireless communication networks in order to enable testing of one or more components. One or more emulation devices can be test devices. Direct RF coupling and / or wireless communication via an RF circuit (e.g., which can include one or more antennas) can be used by emulation devices to transmit and / or receive data.

[0066] The IEEE 802.11UHR Study Group was formed in July 2022 to create a Project Authorization Request (PAR) to create an 802.11 task group to standardize improved reliability of WLAN connectivity, reduce latency, improve manageability, and increase throughput consumption. Millimeter-wave (mmW or mmWave) operation is considered a potential feature to achieve these goals, especially considering the development of Multi-Link Operation (MLO) in 802.11be.

[0067] Millimeter-wave operation can be the most relevant feature to match the UHR goals. All devices operating in the mmW band / link can have MLO capabilities and can have at least one active sub-7GHz link. The discovery and association process can be carried out in the lower band / link. Scheduling and broadcasting are from the lower band / link. Beamforming (BF) training together with Sector Scanning (SS) is carried out in the mmW band / link, but the BF training sequence can be triggered or scheduled from the lower band, and feedback can be provided in the lower band.

[0068] MLO enables non-AP multi-link devices (MLDs) to utilize AP MLD discovery, authentication, association, and establishment of multiple links. An AP associated with an AP MLD (referred to as the reporting AP) can announce the operational capabilities and operational parameters of another AP (referred to as the reported AP) belonging to the same AP MLD by including multi-link elements. Based on the supported capabilities exchanged during association, each link enables channel access and frame exchange between the non-AP MLD and the AP MLD.

[0069] Figure 2 is an exemplary Null Data Packet 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 Probe Dialog Token field 210, one or more STA Information fields 212, and an FCS field 214. Figure 3 is an exemplary Probe Dialog Token field format 300 in the NDPA frame. The Probe Dialog Token field may include an NDPA Variable field 302 and a Probe Dialog Token Number field 304. As listed in Table 1 below, in 802.11, according to the definition of the Probe Dialog Token field, there can be four variants of NDPA.

[0070] Table 1 - Definition of Probe Dialog Token Figure 4 is an exemplary STA Information field format in the EHT NDPA frame. The STA Information field may include an AID11 field 402, a Partial BW Information 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.

[0071] One potential issue with mmW signals is that they may be vulnerable to changes in the propagation environment and have inherent limitations due to high propagation losses. Beamforming is a fundamental requirement for successful operation in mmW. Analog beamforming may work better for mmW operation to reduce complexity. Locking the best beams for transmission and reception may require frequent beam training. In the multi-link operation (MLO) framework, it may be more efficient to use a link in the sub-7 GHz band to exchange control frames (such as NDPA frames and trigger frames), while physical layer protocol data units (PPDUs) containing training symbols (such as NDP) should be transmitted over the mmW link. Beam training using the MLO framework requires defining methods and procedures to achieve efficient operation in mmW.

[0072] A second potential issue is that the best transmission beam for data transmission can be blocked due to the mobility of non-AP STAs or environmental changes. In such a scenario, the AP or non-AP STA can initiate a beam recovery process to lock onto a clean beam and resume the transmission to the non-AP or AP STA respectively. The beam recovery process can efficiently minimize latency and improve the reliability of the connection. Performing an efficient beam recovery process in mmW using the MLO framework is an open issue.

[0073] In one embodiment, NDPA frames can be used to announce the transmission of NDPs, which can be used for beam training and sector scanning in mmW links. The NDPA can be sent on sub-7 GHz links, while the NDP transmission can occur on mmW links.

[0074] In one embodiment, the Probe Dialog Token field of the NDPA frame can be used to indicate whether the NDPA is a UHR variant NDPA or an mmW variant NDPA. One or more bits from B2 to B7 of the Probe Dialog Token can be used to identify the new variant of the NDPA frame (i.e., UHR NDPA or mmW NDPA).

[0075] In one embodiment, one or more Special STA Information fields can be used in the traditional NDPA design to signal common useful information to all addressed STAs in the NDPA. The Special STA Information field can be indicated by using Figure 4 a special ID in the AID 11 subfield as shown.

[0076] Figure 5 is an exemplary NDPA frame format 500 for UHR and mmW support. In one embodiment, the NDPA control frame can be Figure 5 defined for UHR and mmW operations using the design shown. As Figure 5 shown, the NDPA frame can include a Frame Control field 502, a Duration field 504, an RA field 506, a TA field 508, a Common Information field 510, a STA Information List field 512, and an FCS field 514.

[0077] Although Figure 5 the STA Information field shown is 4 octets, it can have different sizes for flexible and efficient use of the NDPA frame for different purposes, and the size can be indicated in the Common Information field. The size N of the Common Information field can be 1 or more octets.

[0078] Figure 6 is Figure 5 an exemplary Common Information field 510 format 600 of the UHR millimeter-wave NDPA frame as shown.Figure 6 As shown, the common information field may include a Ver sub-field 602, a dialogue token sub-field 604, an STA information size sub-field 606, a BW sub-field 608, a channel perforation information sub-field 610, an Nt sub-field 612, an Nr sub-field 614, a Tx sector number sub-field 616, an Rx sector number sub-field 618, an NDP number sub-field 620, the number of LETs in each NDP sub-field 622, and an NDP Tx power sub-field 624. The common information field may be defined in the NDPA frame and used to indicate common useful information to all addressed STAs in the NDPA, and the common useful information may include version information to indicate the version of the NDPA for future compatibility, such as Figure 5 shown.

[0079] The Ver sub-field 602 may indicate the version of the NDPA. The Ver sub-field 602 may be used for future compatibility, where several different variants of the NDPA may be defined in different modifications to parse the common information field, the special STA information field, and the STA information field may be different for different modifications, or even different for different uses of the same modification. For example, there may be a UHR sounding variant of the NDPA that can be used for channel sounding in the sub-7 GHz band in the UHR, and there may be another variant of the NDPA that can be used for enhanced sensing or enhanced ranging purposes. There may also be variants for mmW beam training and sector scanning and another variant for mmW channel sounding. Ver subfield NDPA variant 0 UHR detect NDPA 1 UHR sense NDPA 2 mmW (beam training / sector scan) NDPA 3 mmW detect NDPA 4-15 Reserved

[0080] Table 2 - Exemplary Encoding of the 4-bit Ver Sub-Field of the Common Information Field in the NDPA Frame The dialogue token number sub-field 604 may be selected by the AP to identify the current session of beam training in order to simply associate the beam training report with the beam training session.

[0081] The STA information size sub-field 606 may explicitly indicate the size in octets of the STA information field in the NDPA frame. The STA information size may also be indicated implicitly, depending on the NDPA frame variant signaled by the Ver sub-field 602.

[0082] The BW sub-field 608 may indicate the bandwidth of the NDP that will be sent on the mmW link after the NDPA has been sent on one or more sub-7 GHz links. The bandwidth of the PPDU that carries the NDPA and is sent in the sub-7 GHz band is different from the bandwidth of the NDP PPDU sent on the mmW link.

[0083] The channel perforation information subfield 610 may indicate a list of perforated channels in the BSS mmW link bandwidth in which the NDP will be transmitted.

[0084] The Nt subfield 612 may indicate the number of transmit antennas at the AP.

[0085] The Nr subfield 614 may indicate the number of receive antennas at the AP.

[0086] The Tx sector count subfield 616 may indicate the number of transmit sectors in which the AP will support in the downlink, and this subfield is also mapped to the number of beams formed in the downlink.

[0087] The Rx sector count subfield 618 may indicate the number of receive sectors in which the AP will support in the uplink. This subfield is also mapped to the number of receive beams in the uplink.

[0088] 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 transmit sector.

[0089] The number of LTFs per NDP subfield 622 may indicate the number of long training fields in each NDP.

[0090] The NDP Tx power subfield 624 may indicate the combined transmit power on all antennas in the entire BSS mmW bandwidth in which the NDP for beam training is transmitted, or it may indicate the transmit power for each subchannel of the bandwidth used to transmit the NDP PPDU.

[0091] Figure 7 is the exemplary STA information field format 700 of the UHR mmW NDPA frame. As Figure 7 shown, the STA information field may include the AID11 subfield 702, the preferred Tx sector ID subfield 704, the preferred Rx sector ID subfield 706, the BW subfield 708, the mmW link ID subfield 710, the need SNR report subfield 712, and the blocking SNR threshold subfield 714.

[0092] The AID11 subfield 702 may indicate the association ID of the STA to which the STA information field is addressed.

[0093] The preferred Tx sector subfield 704 may indicate the ID of the transmit sector that was indicated as the preferred transmit sector in the last beam training session.

[0094] Preferably, the Rx sector subfield 706 may indicate the ID of the transmitting sector that was indicated as the preferred receiving sector in the last beam training session.

[0095] The BW subfield 708 may indicate the bandwidth of the NDP to be transmitted on the mmW link after the NDPA is transmitted on one or more sub-7 GHz links and after the SIFS.

[0096] The mmW link ID subfield 710 may indicate the ID of the mmW link that will be used to transmit the NDP PPDU for beam training.

[0097] The need for SNR reporting subfield 712 may indicate whether a non-AP STA is required to provide SNR measurements for each pair of transmitting and receiving sectors.

[0098] The blocked SNR threshold subfield 714 may indicate the SNR threshold at which a beam is considered to be fully blocked and may not be used for data transmission or reception and should be reported as a blocked beam.

[0099] Figure 8 is an exemplary mmW beam training NDP frame format 800. As Figure 8 shown, the mmW beam training frame may 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.

[0100] In one embodiment, the beam training NDP PPDU may contain a short preamble that has an STF 802 for synchronization, one or more LTFs 804 for beam measurement, and a signal field for signaling the beam training information necessary to identify the beam. The SIG field may be further divided into a mmW U-SIG field 806 and a mmW SIG field 808. The mmW U-SIG field 806 may be used to signal general information that is independent of beam training or the PHY layer version. The mmW SIG field 808 may be used to signal information related to beam training, as Figure 8 shown.

[0101] Figure 9 is another exemplary mmW beam training NDP frame format 900. In one embodiment, additionally or alternatively, the beam training NDP PPDU may contain a Synchronization STF (S-STF) 902 that can be used for initial synchronization, a Synchronization LTF (S-LTF) 904 that can be used for finer synchronization, a mmW U-SIG field 906, a mmW-SIG field 908, and a mmW-LTF 910.

[0102] In one embodiment, the number of LTFs can be signaled in the NDPA frame and in the SIG field of the beam training NDP PPDU.

[0103] In one embodiment, the mmW U-SIG field can contain fields independent of the PHY version to achieve forward compatibility for future modifications after UHR-mmW. The mmW U-SIG field can contain the following sub-fields as listed in Table 3 below.

[0104] Table 3 - Exemplary Design of the mmW U-SIG Field In one embodiment, the mmW-SIG field can contain beam training information. The mmW-SIG field can contain the following sub-fields as listed in Table 4 below.

[0105] Table 4 - Exemplary Design of the mmW-SIG Field Figure 10 An exemplary frame exchange sequence of the entire training process 1000 is illustrated. As Figure 10 described, in one embodiment, an AP and one or more non-AP STAs can participate in one or more beam training sessions. AP 1002 can participate as the initiator of the beam training session, and non-AP STAs 1004 and 1006 can participate as responders to the beam training session. Different control frames or beam training PPDUs of the beam training session can be sent on different links. For example, a sub-7GHz link can be used to send control frames and a mmW link can be used to send beam training PPDUs.

[0106] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP can send an NDPA on one or more sub-7GHz band links in the TXOP immediately declared by the AP. The NDPA can be sent 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 information field, (multiple) special STA information fields, or the STA information field of the NDPA refers to the bandwidth of the beam training NDP PPDU sent immediately after the NDPA.

[0107] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP may switch to one or more links in the mmW band and transmit a beam training NDPP PDU after transmitting an NDPA on a sub-7 GHz band. The NDP PPDU may cover the entire bandwidth of the mmW link, as indicated in the common information field, (multiple) special STA information fields, or the STA information field of the NDPA. The NDP PPDU may have punctured sub-channels within the bandwidth of the PPDU, which may also be indicated in the NDPA. One or more NDP PDUs may be transmitted in each of the available sectors, and each NDP is identified by an NDP ID, a sector ID, and an antenna ID. The number of NDP PDUs transmitted may be greater than or equal to the number of sectors. The AP STA may scan to the next sector and transmit the corresponding NDP(s) intended for transmission in that sector. The NDP may be a SIFS that is separate or separated from any other inter-frame space (IFS). Each NDP may be transmitted at a transmit power equal to the NDP Tx power shown 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 maximum number of receive sectors / beams supported by the non-AP STAs participating in the beam training session.

[0108] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP may switch back to the sub-7 GHz link and transmit a BFRP or any other trigger frame or control frame that is designed to trigger a feedback transmission from non-AP STAs in the uplink.

[0109] In one embodiment, one or more non-AP STAs may participate in the beam training session as responders so that each non-AP STA can be addressed by one or more STA information fields in the NDPA transmitted by the AP that is the initiator of the beam training session.

[0110] In one embodiment, a non-AP STA receives an NDPA transmitted by the AP on the sub-7 GHz link and parses the conversation token field and / or the common information field and / or (multiple) special STA information fields to detect whether the NDPA is initiating a beam training session and collects all the information signaled in the mentioned fields to prepare for the beam training session.

[0111] In one embodiment, a non-AP STA may parse the STA information list to search for the STA information field addressed to itself by checking AID11. If the non-AP STA AID matches one or more STA information fields in the STA information list, the non-AP starts to parse the (multiple) STA information fields and prepares for the beam training session. Otherwise, if the non-AP STA AID does not match any AID11 in the STA information fields in the STA information list, the non-AP STA may stop decoding the NDPA and enter the sleep mode after setting its (multiple) NAV counters.

[0112] In one embodiment, if the non-AP STA is addressed in the STA information list of the NDPA immediately sent on a sub-7 GHz link, the non-AP STA may switch to the (multiple) mmW links and prepare to receive the NDP PPDU that can be sent on the mmW links, as indicated in the STA information field.

[0113] In one embodiment, the non-AP STA may switch its receive beam for each LTF symbol or group of LTF symbols included in the received NDP PPDU transmitted in one of the transmission sectors / beams of the AP. Then, the non-AP may 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 of the SNR, average RSSI, or any other physical measurement of the received group of LTFs to represent the strength or quality of the received signal. If the AP transmits more than one NDP PPDU in the same sector / beam, the non-AP STA may average the measurements over multiple NDP PPDUs. By performing this receiving process, each non-AP should have a measurement of the signal strength or signal quality for each pair of transmit and receive beams.

[0114] In one embodiment, if the SNR report sub-field in the STA information field addressed to the non-AP STA is set to 0, the non-AP STA may be required to prepare a complete report for all transmit and receive sector combinations, otherwise, the non-AP STA may prepare a report only for the best transmit and receive sector pair.

[0115] In one embodiment, if the measured SNR for a given transmit beam and receive beam combination is less than the threshold indicated in the blocking SNR threshold subfield of the STA information field, the transmit beam can be considered to be in a full-blocking state with respect to the receive beam under consideration, and a special value in the beam training report can indicate such a situation. In another embodiment, a non-AP STA can prepare a beam training report only for transmit beam and receive beam pairs that have SNR values greater than or equal to the blocking SNR threshold.

[0116] In one embodiment, a non-AP STA can prepare a beam training report and send it back to the AP as a 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.

[0117] Figure 11 is a flowchart illustrating an exemplary beam training process 1100. In one embodiment, the above beam training process can be illustrated by Figure 11 the flowchart shown.

[0118] At 1102, the non-AP STA can receive an NDPA from the AP over a sub-7 GHz link.

[0119] At 1104, the non-AP STA can identify the NDPA variant as an mmW beam training variant.

[0120] At 1106, the non-AP STA can search for the STA information field addressed to the non-AP STA by checking the AID11 field of each STA information field in the STA information list of the NDPA.

[0121] At 1108, the non-AP STA can determine whether the non-STA AID matches any of the AID11s of the STA information fields in the STA information list. At 1110, if the AID11 does not match, the non-AP STA can stop decoding the NDPA, set one or more NAV counters, and enter the doze mode.

[0122] At 1112, if the AID11 matches, the non-AP STA can decode one or more STA information fields using the matching AID11, and decode the conversation token field, and / or the special STA information field, and / or the common information field.

[0123] At 1114, the non-AP STA can parse the signaling information, prepare a beam training session, and switch to one or more mmW links.

[0124] At 1116, a non-AP STA can receive an NDP PPDU sent immediately after the AP sends an NDPA.

[0125] At 1118, a non-AP STA can switch its receiving wave for each LTF symbol or group of LTF symbols included in the received NDP PPDU sent in one of the transmission sectors / beams of the AP. Then, the non-AP can 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 can also measure the average SNR, average RSSI, or the average of any other physical measurement of the received group of LTFs to represent the strength or quality of the received signal. If the AP sends more than one NDP PPDU in the same sector / beam, the non-AP STA can average the measurements over the multiple NDP PPDUs. By performing this receiving process, each non-AP should have a measurement of the signal strength or signal quality for each pair of transmit and receive beams.

[0126] At 1120, the non-AP STA can switch back to a sub-7 GHz link to receive a beam training trigger frame and send back a beam training feedback report to the AP.

[0127] In one embodiment, beam training for mmW links can consider the time structure for transmission, where time slots in which the transmission of NDP training PPDUs occurs can be defined.

[0128] In one embodiment, additionally or alternatively, a common information field can be defined in the NDPA frame and used to indicate common useful information to all addressed STAs in the NDPA considering time slot transmission, such as Figure 12 shown.

[0129] Figure 12 is an exemplary additional or alternative design of the common information field format 1200. Figure 12 The sub-fields of the common information field in Figure 6 can occur in any possible combination with the common information frame format shown in

[0130] As Figure 12 shown, the additional or alternative design of the common information field can include a Ver sub-field 1202, a conversation token sub-field 1204, a BW sub-field 1206, a channel puncturing information sub-field 1208, an Nt sub-field 1210, an Nr sub-field 1212, a Tx sector number sub-field 1214, a time slot number sub-field 1216, a time slot duration sub-field 1218, a time slot start sub-field 1220, a start time slot sub-field 1222, an LTF number per NDP sub-field 1224, and an NDP Tx power sub-field 1226.

[0131] The number of time slots subfield 1216 may indicate the number of time slots in which the beam training process may occur. Each time slot may contain one or more NDP PPDUs that can be used for beam training. The transmission of the first NDP PPDU in each time slot may occur exactly at the start of the time slot boundary. Subsequent NDP PPDUs (if any) may be sent after the first NDP PPDU and SIFS are separated from each other. The NDP PPDUs may also be sent separated by any inter-frame interval.

[0132] The time slot duration subfield 1218 may indicate the duration of each time slot. This duration may be expressed in time units (such as microseconds), or it may be expressed in terms of the number of OFDM symbols.

[0133] The time slot start subfield 1220 may indicate the time point (T0) at which the first time slot in the mmW link starts. This point may be indicated relative to the end of the NDPA frame. In one example, the time slot start point T0 may be indicated as SIFS or any other IFS that occurs after the end of the NDPA frame.

[0134] The start time slot subfield 1222 may indicate which time slot will be the time slot in which the first NDP PPDU can be sent. In one example, the AP may choose to delay the transmission of the NDP PPDU for one or more time slots starting at the first time slot, and start sending the first NDP PPDU in the start time slot.

[0135] Additionally, in one embodiment, in addition to the subfields listed in Table 4, the mmW-SIG field (as described above) Figure 8 may also contain the time slot information subfields listed in Table 5. Subfield Description Number of time slots Indicates the total number of time slots to be used in this beam training session Time slot ID Indicates the ID of the time slot during which this NDP PPDU is transmitted First NDP Indicates whether this is the first NDP PPDU transmitted in the current time slot Last NDP Indicates whether this is the last NDP PPDU transmitted in the current time slot

[0136] Table 5 - Exemplary Design of the mm WSig Field Figure 13 Illustrates an exemplary frame exchange sequence for a time slot-based beam training process. As Figure 13 shown, in one embodiment, one AP and one or more non-AP STAs may participate in one or more beam training sessions, as Figure 13 shown. AP 1302 may participate as the initiator of the beam training session, and non-AP STAs 1304 and 1306 may participate as responders to the beam training session. The control frames of the beam training session may be sent over the sub-7GHz link, while the beam training NDPPPDUs may be sent over the mmW link.

[0137] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP may send an NDPA in one or more sub-7GHz band links within the TXOP immediately declared by the AP. The NDPA may be sent in a UHR PPDU or any legacy PPDU. The bandwidth of the PPDU carrying the NDPA may be indicated in the SIG field of the PPDU carrying the NDPA. The bandwidth indicated in the common information field, (multiple) special STA information fields, or the STA information field of the NDPA refers to the bandwidth of the beam training NDP PPDU sent immediately after the NDPA.

[0138] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP may switch to one or more links in the mmW band and send a beam training NDP PPDU. The AP may follow a time-slot based structure, where the transmission of the beam training NDP PPDU occurs only within a time slot.

[0139] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP may indicate the time point (T0) of the start of the first time slot in the time slot start sub-field of the common information field in the NDPA frame before the transmission of the beam training NDP. In one example, the T0 point may be indicated as the SIFS after the end of the NDPA frame.

[0140] In one embodiment, an AP that initiates a beam training session and is the holder of the current TXOP may choose to delay the transmission in the first time slot of a set of time slots that will be used to send the beam training NDP PPDU.

[0141] In one embodiment, the AP may choose to transmit one or more NDP PPDUs in the same time slot. The NDP PPDUs transmitted within the time slot may be separated from each other by SIFS or any IFS. The NDP PPDU may cover the entire bandwidth of the mmW link, as indicated by the common information field, (multiple) special STA information fields, or the STA information field of the NDPA. The NDP PPDU may have punctured subchannels within the bandwidth of the PPDU, which may also be indicated in the NDPA. One or more NDP PPDUs may be transmitted in each of the available sectors, and each NDP is identified by an NDP ID, a sector ID, and an antenna ID. The number of transmitted NDPPPDUs may be greater than or equal to the number of sectors. The AP STA scans to the next sector and transmits the corresponding NDP(s) intended to be transmitted in that sector. The transmission of the NDP PPDU for one transmission sector may occur in one or more time slots. Each NDP may be transmitted at a transmit power equal to the NDP Tx power 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 maximum number of receive sectors / beams supported by the non-AP STAs participating in the beam training session.

[0142] In one embodiment, the AP that initiates the beam training session and is the holder of the current TXOP may switch back to a sub-7 GHz link and transmit a BFRP or any other trigger frame or control frame that is designed to trigger the feedback transmission of non-AP STAs in the uplink. The transmission of the trigger frame for soliciting feedback may start at the end boundary of the last time slot in a set of time slots for the mmW beam training session.

[0143] In one embodiment, one or more non-AP STAs may participate in the beam training session as responders so that each non-AP STA can be addressed by one or more STA information fields in the NDPA transmitted by the AP that is the initiator of the beam training session.

[0144] In one embodiment, the non-AP STA may receive the NDPA transmitted by the AP on the sub-7 GHz link and parse the conversation token field and / or the common information field and / or (multiple) special STA information fields to detect whether the NDPA is initiating a beam training session, and collect all the information signaled in the mentioned fields to prepare for the beam training session and set the time structure, where the time slots of the beam training session are defined and signaled in the NDPA frame.

[0145] In one embodiment, a non-AP STA can parse the STA information list to search for the STA information field addressed to itself by looking at the AID11. If the non-AP STA AID matches one or more STA information fields in the STA information list, the non-AP starts parsing the (multiple) STA information fields and prepares for the beam training session. Otherwise, if the non-AP STA AID does not match any of the AID11s in the STA information fields in the STA information list, the non-AP STA can stop decoding the NDPA and enter the sleep mode after setting its (multiple) NAV counters.

[0146] In one embodiment, if the non-AP STA is addressed in the STA information list of the NDPA immediately sent on the sub-7 GHz link, the non-AP STA can switch to the (multiple) mmW link and prepare to receive the NDP PPDU that can be sent on the mmW link as indicated by the STA information field. The non-AP STA can start a counter at point T0 indicating the start boundary of the first time slot. The non-AP can start receiving the NDP PPDU at the start boundary of the start time slot that indicates the time slot in which the first NDP PPDU transmission can occur. If the AP chooses to delay the NDP PPDU transmission in one or more of the first time slots starting at T0, the start time slot can be different from the first time slot.

[0147] In one embodiment, the non-AP STA can switch its receive beam for each LTF symbol or group of LTF symbols included in the received NDP PPDU transmitted in one of the time slots of the time structure in one of the transmit sectors / beams of the AP. Then, the non-AP STA can 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 can also measure the average SNR, average RSSI, or the average of any other physical measurement of the received group of LTFs to represent the strength or quality of the received signal. If the AP transmits more than one NDP PPDU in the same sector / beam in the same time slot or multiple time slots, the non-AP STA can average the measurements over the multiple NDP PPDUs. By performing this receiving process, each non-AP can have a measurement of the signal strength or signal quality for each pair of transmit and receive beams.

[0148] In one embodiment, the non-AP STA can prepare a beam training report and send it back to the AP as a response to the 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 on the (multiple) sub-7 GHz link.

[0149] Figure 14is a flowchart illustrating an exemplary slot-based beam training process. In one embodiment, the above beam training process may be illustrated by Figure 14 the flowchart shown, which takes into account the time structure defined by slots for managing the transmission of NDP PPDUs.

[0150] At 1402, a non-AP STA may receive an NDPA from the AP on a sub-7 GHz link.

[0151] At 1404, the non-AP STA may identify the NDPA variant as an mmW beam training variant.

[0152] At 1406, the non-AP STA may search for the STA information field addressed to the non-AP STA by checking the AID11 field of each STA information field in the STA information list of the NDPA.

[0153] At 1408, the non-AP STA determines whether the non-STA AID matches any of the AID11s of the STA information fields in the STA information list. At 1410, if the AID11 does not match, the non-AP STA may stop decoding the NDPA, set one or more NAV counters, and enter the sleep mode.

[0154] If the AID11 matches, at 1412, the non-AP STA may decode one or more STA information fields using the matching AID11, and decode the conversation token field, and / or the special STA information field, and / or the common information field.

[0155] At 1414, the non-AP STA may parse the signaling information, prepare for a beam training session, switch to one or more mmW links, and set the time structure based on the start time (T0), slot duration, number of slots, and starting slot.

[0156] At 1416, the non-AP STA may receive the NDP PPDUs sent in the starting slot and subsequent slots.

[0157] In 1418, the non-AP STA can switch its receive beam for each LTF symbol or group of LTF symbols included in the received NDPP PDU transmitted in one of the transmit sectors / beams of the AP. Then, the non-AP can 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 can also measure the average SNR, average RSSI, or the average of any other physical measurement of the received LTF group to represent the strength or quality of the received signal. If the AP transmits more than one NDP PPDU in the same sector / beam, the non-AP STA can average the measurements over the multiple NDP PPDUs. By performing this receive procedure, each non-AP should have a measurement of the signal strength or signal quality for each pair of transmit and receive beams.

[0158] In 1420, the non-AP STA can switch back to the sub-7 GHz link to receive a beam training trigger frame and send back a beam training feedback report to the AP.

[0159] In one embodiment, as described above, the beam training method and procedure for identifying the best transmit and receive beam pairs operating in the downlink (transmission from the AP STA to the non-AP STA) can be used mutually as the preferred beam pairs for transmission in the uplink (transmission from the non-AP STA to the AP STA). The best transmit beam in the downlink transmission from the AP to the non-AP STA can be used as the best receive beam in the uplink transmission from the non-AP STA to the AP, and the best receive beam in the downlink transmission from the AP to the non-AP STA can be used as the best transmit beam in the uplink transmission from the non-AP STA to the AP STA.

[0160] In one embodiment, beam failure can be triggered by an event when the number of consecutive ACK or BlockACK not received by the transmitter of the PPDU sent to the same STA is equal to or greater than N (N is a system parameter). N can be carried in a beacon or other management frame. For example, if the transmitter AP of the PPDU does not receive an ACK or Block ACK during N consecutive PPDU transmissions to the same STA, the AP can determine that this is a beam failure between the AP and the recipient STA.

[0161] In one embodiment, after detecting beam failure, the AP STA can initiate a beam recovery process with one or more non-AP STAs. In one example, the AP can detect 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 process can be initiated pairwise with one non-AP STA at a certain moment, or can be initiated simultaneously with more than one non-AP STA. In another embodiment, the beam recovery process can be initiated by the (multiple) non-AP STAs.

[0162] In one embodiment, the non-AP STA can continuously report physical layer measurements, such as the RSSI or SNR of data packets sent on a given transmit beam and receive beam pair. Then, if the measurement is below a given threshold, the AP STA can declare beam failure. The AP can also count the number of beam failure events detected, and if the number of beam failures exceeds a certain preset value, initiate a beam recovery process. The threshold of the RSSI or SNR for detecting a beam failure event can be set to a static value announced in a beacon frame or any other management frame. The threshold of the RSSI or SNR for detecting a beam failure event can also be dynamically set using an NDPA frame or any control frame that first initiates beam training. The number of beam failure events to initiate a beam recovery process can be set to a static value announced in a beacon frame or any other management frame. The number of beam failure events to initiate a beam recovery process can also be dynamically set using an NDPA frame or any control frame that first initiates beam training.

[0163] In one embodiment, an information element named beam recovery element can be added to a beacon frame, an association request frame, an association response frame, a re-association request frame, a re-association response frame, a probe request frame, a probe response frame, or any other management frame for managing operations in a BSS or Multi-AP, as an exemplary indication in the beacon frame in Table 6 below.

[0164] Figure 15 is the exemplary beam recovery element format 1500. In one embodiment, the beam recovery element can be used to statically configure the beam recovery process. As Figure 15 shown, the beam recovery element can include an element ID field 1502, a length field 1504, an element ID extension field 1506, and a beam recovery control field 1508.

[0165] Figure 16 is the exemplary beam recovery control field format 1600 as shown in 1508. As Figure 16As shown, the beam recovery control field may include a beam failure SNR threshold sub-field 1602, a maximum beam failure count sub-field 1604, a beam failure timer sub-field 1606, and a reserved sub-field 1608.

[0166] The beam failure SNR threshold sub-field 1602 may signal an SNR level at which the beam is considered to be in a failed state. An exemplary encoding of this sub-field is shown in Table 7 below.

[0167] The maximum beam failure count sub-field 1604 may signal the number of beam failure events under which the beam will be considered unreliable and the STA will initiate a beam recovery process. An exemplary encoding of this sub-field is shown in Table 8 below.

[0168] The beam failure timer sub-field 1606 may signal an initial value of a timer that is initialized and starts counting once a beam failure event is detected, and if the timer reaches 0 before another beam failure occurs, a counter that counts the number of beam failure events may be reset to 0.

[0169] Table 6 - Beacon Frame Body Table 7 - Exemplary Encoding of Beam Failure SNR Threshold Sub-field Maximum beam failure number subfield Maximum beam failure number value 000 4 001 8 010 16 011 32 100 64 101-111 Reserved Table 8 - Exemplary Encoding of Maximum Beam Failure Count Sub-field In one embodiment, the NDPA for initiating a beam training session may also signal the configuration of the beam recovery process.

[0170] Figure 17 is an exemplary common information field frame format 1700 for the dynamic configuration of the beam recovery process. The common information field frame for the dynamic configuration of the beam recovery process may include a Ver sub-field 1702, a dialogue token sub-field 1704, a BW sub-field 1706, a channel puncturing information sub-field 1708, an Nt sub-field 1710, an Nr sub-field 1712, a Tx sector count sub-field 1714, a beam failure SNR threshold 1716, a maximum beam failure count 1718, a beam failure timer 1720, a number of LRFs per NDP sub-field 1722, and an NDP Tx power sub-field 1724.

[0171] As Figure 17As shown, the common information field, the (multiple) special STA information field, or the (multiple) STA information field may include one or more of the following sub-fields: beam failure SNR threshold, maximum number of beam failures, and a beam failure timer that can be used to dynamically configure the beam recovery process.

[0172] In one embodiment, whenever 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 the beam failure counter. 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 the beam recovery process. Figure 18 Illustrates an exemplary beam failure detection process.

[0173] In one embodiment, after detecting a beam failure, the beam recovery process may be initiated by the AP STA. The beam recovery process may start by sending an mmW beam training NDPA on the sub-7GHz link and then sending a series of NDP PPDUs on the mmW link, which may follow the same process as for initial beam training. Then, the AP may send a trigger frame to request a beam training report on the sub-7GHz link.

[0174] In one embodiment, the NDPA sent to initiate beam recovery may include a STA information field that addresses the non-AP STA to which the beam connecting the non-AP STA to the AP is declared to be in a beam failure state. The NDPA may also include STA information fields for other non-STAs that are performing initial beam training or whose beams are declared to be in a beam failure state.

[0175] In one embodiment, after triggering a beam failure in the MAC layer of the non-AP STA, the non-AP STA may send a frame to the AP indicating a beam failure in the lower band link. Then, this signal may be carried in a control frame, for example, an ACK or Block frame, or the A control field of a management frame or data frame.

[0176] Figure 18 Is a flowchart of an exemplary beam failure detection process.

[0177] At 1802, the non-AP STA may measure the SNR of the LTF in the preamble of the received data packet.

[0178] At 1804, the non-AP STA may determine whether the measured SNR is less than the beam failure SNR threshold. If the measured SNR is not less than the beam failure SNR threshold, the non-AP STA may return to 1804 and continue to measure the SNR.

[0179] If the measured SNR is less than the beam failure SNR threshold, then at 1806, the non-AP STA may increment the beam failure counter by 1, reset the beam failure timer, start a timer on the beam failure timer, and receive the next packet.

[0180] At 1808, the non-AP STA may determine whether the beam failure timer has reached 0 before detecting a new beam failure event. If the beam failure timer has not reached 0, the non-AP STA returns to 1806 and increments the beam failure counter by 1 in the case where another measured SNR is less than the beam failure SNR threshold.

[0181] 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.

[0182] At 1812, the non-AP STA may determine whether the beam failure counter has reached the maximum beam failure number. If the beam failure counter has indeed reached the maximum beam failure number, then at 1814, the non-AP STA may initiate a beam recovery process. If the beam failure counter has not reached the maximum beam failure number, the non-AP STA may return to 1802.

[0183] Figure 19 is a flowchart illustrating an exemplary beam training process 1900. In one embodiment, the beam training process explained above may be illustrated by the Figure 19 flowchart described in

[0184] At 1902, the non-AP STA may receive an NDPA on the sub-7 GHz link of the STA. 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 information field in the NDPA frame has an AID sub-field that matches the association ID (AID) associated with the STA. At 1906, the non-AP STA may determine the STA sub-field information corresponding to the mmW beam training session based on the matching AID. At 1908, the non-AP STA may receive one or more NDP PPDUs on the mmW link based on the STA sub-field information. At 1910, the non-AP STA may send a beam training feedback report on the sub-7 GHz link based on one or more NDP PPDUs received on the mmW link.

[0185] While the features and elements of the present invention are described in a preferred embodiment in a specific combination, each feature or element can be used alone without the other features and elements of the preferred embodiment, or in various combinations with or without the other features and elements of the present invention.

[0186] While the solutions described herein contemplate 802.11 specific protocols, it should be understood that the solutions described herein are not limited to such scenarios and are equally applicable to other wireless systems. While SIFS is used in the examples of the design and process to indicate various inter-frame intervals, all other inter-frame intervals, such as RIFS, AIFS, DIFS, or other agreed-upon time intervals, can be applied to the same solution. While the sub-7GHz link / band is used to refer to the link in the MLO system where control / management frames can be sent over the mmW link / band, it can be replaced by a more general term (such as a low-frequency link / band).

[0187] While the first field / sub-field / element / sub-element may be defined in the second field / sub-field / element / sub-element / frame, the first field / sub-field / element / sub-element may be carried in other fields / sub-fields / elements / sub-elements / frames to indicate the same information.

[0188] While the NDPA frame transmitted over the sub-7GHz link to schedule beam training over the mmW link is described above, the NDPA frame can be replaced or renamed by other management frames or control frames having similar information and signaling disclosed herein.

[0189] While the NDP PPDU / frame transmitted over the mmW link is described above, the NDP PPDU / frame can be replaced or renamed by another management frame or control frame having a similar design and signaling disclosed herein.

[0190] The long training field (LTF) can be any type of predefined sequence known to both the transmitter side and the receiver side.

[0191] While features and elements have been described above in particular combinations, one of ordinary skill in the art will understand that each feature or element can be used alone or in any combination with other features and elements. Additionally, the methods described herein can be implemented in a computer program, software, or firmware incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent 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, caches, 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 associated with the software can be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, and / or any host computer.

Claims

1. A method performed by a station (STA), the method comprising: Receiving an Null Data Packet (NDP) Announcement (NDPA) frame on a sub-7GHz link of the STA, wherein the NDPA includes information for initiating a millimeter wave (mmW) beam training process; Determining that at least one STA information field included in the NDPA frame includes an AID sub-field 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 information field; And Transmitting a beam training feedback report on the sub-7GHz link based on the one or more NDP PPDUs received on the mmW link.

2. The method according to claim 1, wherein the NDPA includes a common information field.

3. The method according to claim 2, wherein the common information field includes at least one of a Ver sub-field, a dialogue token number sub-field, an STA information size sub-field, a BW sub-field, a channel puncturing information sub-field, an Nt sub-field, an Nr sub-field, a Tx sector number sub-field, an Rx sector number sub-field, an NDP number sub-field, an LTF number sub-field in each NDP, or an NDP Tx power sub-field.

4. The method according to claim 1, wherein the STA information field includes at least one of an AID11 sub-field, a preferred Tx sector ID sub-field, a preferred Rx sector ID sub-field, a BW sub-field, an mmW link ID sub-field, a need SNR report sub-field, or a blocking SNR threshold sub-field.

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

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

8. A station (STA), the station comprising: One or more transceivers and a processor, configured to: Receive an Null Data Packet (NDP) Announcement (NDPA) frame on a sub-7GHz link of the STA, wherein the NDPA includes information for initiating a millimeter wave (mmW) beam training process; Determine that at least one STA information field included in the NDPA frame has an AID sub-field that matches an Association ID (AID) associated with the STA; Receive one or more NDP physical layer protocol data units (PPDUs) on the mmW link based on the information included in the STA information field; and On the sub-7 GHz link, send a beam training feedback report based on the one or more NDP PPDUs received on the mmW link.

9. The STA according to claim 8, wherein the NDPA includes a common information field.

10. The STA according to claim 9, wherein the common information field includes at least one of a Ver sub-field, a conversation token number sub-field, an STA information size sub-field, a BW sub-field, a channel puncturing information sub-field, an Nt sub-field, an Nr sub-field, a Tx sector number sub-field, an Rx sector number sub-field, an NDP number sub-field, an LTF number sub-field in each NDP, or an NDP Tx power sub-field.

11. The STA according to claim 1, wherein the STA information field includes at least one of an AID11 sub-field, a preferred Tx sector ID sub-field, a preferred Rx sector ID sub-field, a BW sub-field, an mmW link ID sub-field, a need SNR report sub-field, or a blocked SNR threshold sub-field.

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

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

Images