Method of resource determination for beam failure recovery in higher frequency communications

Abstract

Methods for determining candidate beams for beam failure recovery are provided herein. A method performed by a wireless transmit / receive unit (WTRU) includes receiving configuration information for receiving a set of first reference signals associated with a set of first beams, receiving configuration information for receiving a set of second reference signals associated with a set of second beams, and one or more criteria for candidate beam selection. The method includes receiving at least one of a set of first reference signals. The method includes transmitting information indicating a set of selected third beams that meet the criteria for the received candidate beam selection. The selected set of third beams is a set of suggested candidate beams to be monitored for beam failure recovery. The set of third beams is selected based on beam quality measurements of one of the sets of first reference signals.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 410,958, filed on September 28, 2022, the content of which is incorporated herein by reference. Background of the Invention

[0003] Beam failure detection and recovery are important functions in beam - based communication systems, such as those operating according to the Fifth Generation (5G) specifications of the Third Generation Partnership Project (3GPP). A wireless transmit / receive unit (WTRU) in such a system can monitor the quality of the (one or more) beams in use through resources such as beam failure detection resources. When a beam failure is detected, one or more alternative beams can be selected from a set of configured candidate beams.

[0004] In systems operating according to Release 16 and Release 17 specifications, candidate beams can be configured semi - statically by a base station (e.g., gNB) for each WTRU. Due to the narrow beamwidth and the fact that the base station / WTRU relies on current or recent beam measurement values to determine candidate beams, this type of configuration may require many candidate beams to support systems operating in higher frequency ranges, such as Frequency Range 2 - 2 (FR2 - 2). Otherwise, the beam failure recovery process may often fail to provide a suitable new beam. However, due to the use of Time Division Duplex (TDD) in beam scanning, using many candidate beams may reduce system throughput and increase power consumption in the WTRU.

[0005] To avoid the need for many candidate beams, it may be beneficial for the WTRU and the base station to support the use of a dynamic set of candidate beams and perform beam prediction using artificial intelligence / machine learning (AI / ML) - based methods during the candidate beam determination process. Dynamically configuring the WTRU with a set of reference signals (e.g., a set of Beam Failure Detection Reference Signals (BFD - RS)) and selecting / configuring the WTRU with a set of dynamic related parameters can improve the efficiency of the BFD process and reduce overhead. Summary of the Invention

[0006] A method for determining candidate beams for beam failure recovery performed by a wireless transmit / receive unit (WTRU) is provided. The method involves receiving configuration data for a set of two reference signals associated with a set of two beams and criteria for candidate beam selection. When at least one reference signal from the first set of beams is received, the WTRU may transmit details specifying a third set of beams. The third set selected based on beam quality measurements from the received reference signals may meet the specified criteria and may be used as a recommended candidate beam for beam failure monitoring and recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals in the figures indicate like elements and in which:

[0008] Figure 1A is a system diagram illustrating an example communication system in which one or more of the disclosed embodiments may be implemented;

[0009] Figure 1B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communication system illustrated in Figure 1A ;

[0010] Figure 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system illustrated in Figure 1A ;

[0011] Figure 1D is a system diagram illustrating an additional example RAN and an additional example CN that may be used within the communication system illustrated in Figure 1A ;

[0012] Figure 2 is a Venn diagram representation of a set of candidate beams and a set of active candidate beams of the set of candidate beams;

[0013] Figure 3 is a diagram illustrating an example of a beam failure recovery process performed by a base station and a WTRU;

[0014] Figure 4 is a diagram illustrating an example of a beam failure recovery process performed by a base station and a WTRU;

[0015] Figure 5 is based on the equation Venn diagram representation of the determined set of candidate beams;

[0016] Figure 6is a diagram illustrating an example of a CFRA - BFR process performed by a WTRU using location / time - based determination; and

[0017] Figure 7 is a flow chart illustrating steps for FR2 candidate beam set determination by a WTRU using FR1 beam quality measurements of an AI / ML model. Detailed Description

[0018] Figure 1A 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, broadcasting, etc. to a plurality of wireless users. The communication system 100 may enable a plurality of wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single - carrier FDMA (SC - FDMA), zero - tail unique - word discrete Fourier transform - spread OFDM (ZT - UW - DFT - S - OFDM), unique - word OFDM (UW - OFDM), resource - block filtered OFDM, filter - bank multicarrier (FBMC), and the like.

[0019] As Figure 1AAs shown in FIG. 0, 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. However, it will be understood 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 hotspot 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 environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, and the like. Any one of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0020] The communication system 100 may further include base stations 114a and / or base stations 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a NodeB, an eNode B (eNB), a home node B, a home eNode B, a next-generation NodeB (such as a gNode B (gNB), a New Radio (NR) NodeB), a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0021] Base station 114a may be part of RAN 104, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, and the like. 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 cells (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 wireless services to a specific geographical area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with 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 an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize 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.

[0022] 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, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). Any suitable radio access technology (RAT) may be used to establish air interface 116.

[0023] More specifically, as noted above, communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, base station 114a in RAN 104 and WTRUs 102a, 102b, 102c may implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish air interface 116. WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed Uplink (UL) Packet Access (HSUPA).

[0024] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as evolved UMTS terrestrial radio access (E-UTRA), which may use long term evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-A Pro to establish an air interface 116.

[0025] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology (such as NR radio access), which may use NR to establish an air interface 116.

[0026] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may 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 may 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).

[0027] 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), GSM enhanced data rate evolution (EDGE), GSM EDGE (GERAN), and the like.

[0028] Figure 1AThe base station 114b therein can be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point, and can utilize any suitable RAT to facilitate wireless connections 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 can implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d can implement a radio technology 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 can 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 can 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.

[0029] The RAN 104 can communicate with the CN 106, which can 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 can have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 can provide call control, billing services, location-based services for mobile, prepaid calling, Internet connection, video distribution, etc., and / or perform advanced security functions such as user authentication. Although not shown in Figure 1A it will be understood that the RAN 104 and / or the CN 106 can communicate directly or indirectly with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104 that can utilize NR radio technology, the CN 106 can also communicate with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0030] CN 106 can also serve as a gateway for WTRU 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 can include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 can 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 can include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 can include another CN connected to one or more RANs, and the one or more RANs can employ the same RAT or a different RAT as the RAN 104.

[0031] Some or all of the WTRU 102a, 102b, 102c, 102d in the communication system 100 can include multi-mode capabilities (e.g., the WTRU 102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks over different wireless links). For example, Figure 1A the WTRU 102c shown in can be configured to communicate with a base station 114a that can employ a cellular-based radio technology and with a base station 114b that can employ IEEE 802 radio technology.

[0032] Figure 1B is a system diagram illustrating an example WTRU 102. As Figure 1B shown, among other things, the WTRU 102 can also include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 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. It will be understood that the WTRU 102 can include any sub-combination of the foregoing elements while remaining consistent with the embodiments.

[0033] 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, and the like. The processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120, which can be coupled to the transmit / receive element 122. Although Figure 1B the processor 118 and the transceiver 120 are depicted as separate components, it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0034] The transmit / receive element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via the 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, for example, 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 signals and optical signals. It will be understood that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0035] 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.

[0036] 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, the transceiver 120 can include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs (such as NR and IEEE 802.11), for example.

[0037] The processor 118 of the WTRU 102 may be coupled to the speaker / microphone 124, keypad 126, and / or the 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 the speaker / microphone 124, keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from any type of suitable memory (such as the non-removable memory 130 and / or the removable memory 132) and store data in any type of suitable 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, and the like. In other embodiments, the processor 118 may access information from a memory that is not physically located on the WTRU 102 (such as a server or a home computer (not shown)) and store data in that memory.

[0038] The processor 118 may receive power from a power supply 134 and may be configured to distribute and / or control 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 battery packs (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), a solar cell, a fuel cell, and the like.

[0039] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of 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 understood that the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with the embodiments.

[0040] The processor 118 may be further coupled to other peripheral devices 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connections. For example, the peripheral device 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, 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, and the like. The peripheral device 138 may include one or more sensors. The sensor may 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 the like.

[0041] The WTRU 102 may 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)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating 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 an embodiment, the WTRU 102 may 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)).

[0042] Figure 1C is a system diagram illustrating a RAN 104 and a CN 106 according to an embodiment. As noted above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRU 102a, 102b, 102c via the air interface 116. The RAN 104 may also communicate with the CN 106.

[0043] The RAN 104 may include eNode-Bs 160a, 160b, 160c, but it will be understood that while remaining consistent with the embodiments, the RAN 104 may include any number of eNode-Bs. Each of the eNode-Bs 160a, 160b, 160c may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c via 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 use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0044] 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, and the like. As Figure 1C shown, the eNode-Bs 160a, 160b, 160c may communicate with each other via the X2 interface.

[0045] Figure 1C The CN 106 shown 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 understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0046] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via the S1 interface and may serve 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, and the like. 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.

[0047] 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 generally 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 handovers between eNode Bs, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the contexts of the WTRUs 102a, 102b, 102c, and the like.

[0048] 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.

[0049] 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 (such as an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108 or can communicate with the IP gateway. 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.

[0050] Although the WTRU is Figures 1A - 1D described as a wireless terminal herein, in some representative embodiments, such a terminal can (e.g., temporarily or permanently) use a wired communication interface to the communication network.

[0051] In a representative embodiment, the other network 112 can be a WLAN.

[0052] A WLAN in infrastructure basic service set (BSS) mode 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 to and / or from the BSS. Traffic originating from outside the BSS and destined for an STA can reach the STA through the AP and can be delivered to the STA. Traffic originating from an STA and destined for 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 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-to-peer traffic. Peer-to-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 independent BSS (IBSS) mode may 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 as the "ad-hoc" communication mode in this document.

[0053] When using the 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., 20 MHz bandwidth) or dynamically set width. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, for example, carrier sense multiple access / collision avoidance (CSMA / CA) can be implemented in an 802.11 system. For CSMA / CA, the STA (e.g., each STA) (including the AP) can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0054] A high throughput (HT) STA can communicate using a 40 MHz wide channel, e.g., by combining the primary 20 MHz channel with an adjacent or non-adjacent 20 MHz channel to form a 40 MHz wide channel.

[0055] 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 pass through a segment parser that can split the data into two streams. The inverse fast Fourier transform (IFFT) processing and time domain processing can be performed separately on each stream. These streams can be mapped to two 80 MHz channels, and the data can be transmitted by a transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration can be reversed, and the combined data can be sent to the media access control (MAC).

[0056] 802.11af and 802.11ah support operation modes below 1 GHz. The channel operation bandwidth and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV white space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support meter type control / machine type communication (MTC), such as MTC devices in a macro coverage area. The MTC devices can have certain capabilities, such as limited capabilities, including supporting (e.g., only supporting) certain bandwidths and / or limited bandwidths. The MTC devices can include a battery with a battery life above a threshold (e.g., for maintaining a very long battery life).

[0057] A WLAN system that can support multiple channels and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah includes channels 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 (which supports the minimum bandwidth operation mode) from 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, because an STA (which only supports the 1MHz operation mode) is transmitting to the AP, then all available frequency bands can be considered busy even if most of the available frequency bands remain idle.

[0058] In the United States, the available frequency bands available for 802.11ah are from 902MHz to 928MHz. In Korea, the available frequency bands are from 917.5MHz to 923.5MHz. In Japan, the available frequency bands are from 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0059] Figure 1D FIG. is a system diagram illustrating RAN 104 and CN 106 according to an embodiment. As noted above, RAN 104 can employ NR radio technology to communicate with WTRUs 102a, 102b, 102c via air interface 116. RAN 104 can also communicate with CN 106.

[0060] The RAN 104 may include gNBs 180a, 180b, 180c, but it will be understood that while remaining consistent with the embodiments, the RAN 104 may include any number of gNBs. Each of the gNBs 180a, 180b, 180c may include one or more transceivers to communicate with the WTRUs 102a, 102b, 102c via the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b 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 and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive a coordinated transmission from the gNB 180a and the gNB 180b (and / or gNB 180c).

[0061] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with a 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 an absolute time length that varies continuously).

[0062] gNBs 180a, 180b, 180c can be configured to communicate with WTRUs 102a, 102b, 102c in a stand-alone configuration and / or a non-stand-alone configuration. In a stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c without accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In a stand-alone configuration, WTRUs 102a, 102b, 102c can use one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In a stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with or connect to gNBs 180a, 180b, 180c while also communicating with or connecting to other RANs (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 a non-stand-alone configuration, eNode-Bs 160a, 160b, 160c can be used as a mobility anchor for WTRUs 102a, 102b, 102c, and gNBs 180a, 180b, 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, 102c.

[0063] 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, DC, interworking between NR and E-UTRA, 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, and the like. As Figure 1D shown, gNBs 180a, 180b, 180c can communicate with each other via the Xn interface.

[0064] Figure 1DThe CN 106 shown in [Figure] may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and may include data networks (DN) 185a, 185b. Although the foregoing elements are depicted as part of CN 106, it will be understood that any of these elements may be owned and / or operated by entities other than the CN operator.

[0065] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selection of a specific SMF 183a, 183b, management of the registration area, termination of non-access stratum (NAS) signaling, mobility management, and the like. The AMF 182a, 182b may use network slicing to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service used by the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different usage scenarios (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, and the like). 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).

[0066] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic passing through the UPF 184a, 184b. 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, and the like. The PDU session type may be IP-based, non-IP-based, Ethernet-based, and the like.

[0067] UPF 184a and 184b can be connected to one or more of gNBs 180a, 180b, and 180c in RAN 104 via the N3 interface, and the N3 interface can provide access to a packet switched network (such as the Internet 110) to WTRUs 102a, 102b, and 102c to facilitate communication between WTRUs 102a, 102b, and 102c and IP-enabled devices. UPF 184a and 184b can perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, and the like.

[0068] 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) that serves as an interface between CN 106 and the PSTN 108 or can communicate with the IP gateway. Additionally, CN 106 can provide access to other networks 112 to WTRUs 102a, 102b, and 102c, and the other networks can include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRUs 102a, 102b, and 102c can be connected to local DNs 185a and 185b via UPF 184a and 184b through the N3 interface to UPF 184a and 184b and the N6 interface between UPF 184a and 184b and DNs 185a and 185b.

[0069] In view of Figures 1A - 1D and Figures 1A - 1D in view of the corresponding descriptions, one or more or all of the functions described herein with reference to one or more of the following: WTRUs 102a - 102d, base stations 114a - 114b, eNode-Bs 160a - 160c, MME 162, SGW 164, PGW 166, gNBs 180a - 180c, AMFs 182a - 182b, UPFs 184a - 184b, SMFs 183a - 183b, DNs 185a - 185b, and / or any other device(s) described herein (one or more) can be performed by one or more emulation devices (not shown). 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.

[0070] Emulation devices can be designed to implement one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, the 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. The one or more emulation devices can perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. An emulation device can be directly coupled to another device for testing purposes and / or perform tests using wireless communication over the air.

[0071] The one or more emulation devices can perform one or more (including all) functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, an emulation device can be used in a test laboratory and / or in a test scenario in a non-deployed (e.g., test) wired and / or wireless communication network in order to implement tests of one or more components. The one or more emulation devices can be test equipment. Direct RF coupling and / or wireless communication via an RF circuit system (e.g., which can include one or more antennas) can be used by the emulation device for transmitting and / or receiving data.

[0072] Various abbreviations that may be used herein are set forth below:

[0073] Δf Subcarrier spacing

[0074] K0 PDSCH scheduling offset (in number of slots)

[0075] K2 PUSCH scheduling offset (in number of slots)

[0076] ∪ Union

[0077] AP Aperiodic

[0078] BF Beam failure

[0079] BFR Beam failure recovery

[0080] BFD-RS Beam failure detection - reference signal

[0081] BLER Block error rate

[0082] BR Beam resource

[0083] BWP Bandwidth part

[0084] CA Carrier aggregation

[0085] CB Contention-based (e.g., access, channel, resource)

[0086] CBRA Contention-Based Random Access

[0087] CBRA-BFR CBRA Beam Failure Recovery

[0088] CDM Code Division Multiplexing

[0089] CFRA Contention-Free Random Access

[0090] CFRA-BFR CFRA Beam Failure Recovery

[0091] CG Cell Group

[0092] CoMP Coordinated Multipoint Transmission / Reception

[0093] CP Cyclic Prefix

[0094] CPE Common Phase Error

[0095] CP-OFDM Conventional OFDM (Cyclic Prefix Dependent)

[0096] CQI Channel Quality Indicator

[0097] CN Core Network (e.g., LTE Packet Core or NR Core)

[0098] CORESET Control Resource Set

[0099] CRC Cyclic Redundancy Check

[0100] CSI Channel State Information

[0101] CSI-RS Channel State Information - Reference Signal

[0102] CU Central Unit

[0103] D2D Device-to-Device Transmission (e.g., LTE Sidelink)

[0104] DC Dual Connectivity

[0105] DCI Downlink Control Information

[0106] DL Downlink

[0107] DMRS Demodulation Reference Signal

[0108] DRB Data Radio Bearer

[0109] DU Distributed Unit

[0110] EN-DC E-UTRA–NR Dual Connectivity

[0111] EPC Evolved Packet Core

[0112] FD-CDM Frequency Domain Code Division Multiplexing

[0113] FDD Frequency Division Duplexing

[0114] FDM Frequency Division Multiplexing

[0115] ICI Inter-Cell Interference

[0116] ICIC Inter-Cell Interference Cancellation

[0117] IP Internet Protocol

[0118] IRS Intelligent Reflecting Surface

[0119] LBT Listen Before Talk

[0120] LCH Logical Channel

[0121] LCID Logical Channel IDentifier

[0122] LCP Logical Channel Priority

[0123] LLC Low Latency Communication

[0124] LoS Line of Sight

[0125] LTE Long Term Evolution, e.g., from 3GPP LTE R8 and above

[0126] MAC Media Access Control

[0127] MAC-CE MAC Control Element

[0128] NACK Negative ACK

[0129] MBMS Multimedia Broadcast Multicast Service

[0130] MCG Master Cell Group

[0131] MCS Modulation and Coding Scheme

[0132] MIMO Multiple-Input Multiple-Output

[0133] MTC Machine-Type Communication

[0134] MR-DC Multi-RAT Dual Connectivity

[0135] NAS Non-Access Stratum

[0136] NCB-RS New Candidate Beam Reference Signal

[0137] NE-DC NR-RAN–E-UTRA Dual Connectivity

[0138] NLoS Non-Line of Sight

[0139] NR New Radio

[0140] NR-DC Dual Connectivity

[0141] OFDM Orthogonal Frequency Division Multiplexing

[0142] OOB Out-of-Band (emission)

[0143] P cmax Total available WTRU power within a given transmission interval

[0144] Pcell Primary cell of the primary cell group

[0145] PCG Primary cell group

[0146] PDCCH Physical Downlink Control Channel

[0147] PDU Protocol Data Unit

[0148] PER Packet Error Rate

[0149] PHY Physical layer

[0150] PLMN Public Land Mobile Network

[0151] PLR Packet Loss Rate

[0152] PRACH Physical Random Access Channel

[0153] PRB Physical Resource Block

[0154] PRS Positioning Reference Signal

[0155] Pscell Primary cell of the secondary cell group

[0156] PSS Primary Synchronization Signal

[0157] PT-RS Phase Tracking Reference Signal

[0158] PUCCH Physical Uplink Control Channel

[0159] QoS Quality of Service (from the perspective of the physical layer)

[0160] RAB Radio Access Bearer

[0161] RAN PA Radio Access Network Paging Area

[0162] RACH Random Access Channel (or procedure)

[0163] RAR Random Access Response

[0164] RAT Radio Access Technology

[0165] RB Resource Block

[0166] RCU Radio Access Network Central Unit

[0167] RF Radio Front End

[0168] RE Resource Element

[0169] RIS Reconfigurable Intelligent Surface

[0170] RLF Radio Link Failure

[0171] RLM Radio Link Monitoring

[0172] RNTI Radio Network Temporary Identifier

[0173] ROM Read-Only Mode (for MBMS)

[0174] RRC Radio Resource Control

[0175] RRM Radio Resource Management

[0176] RS Reference Signal

[0177] RTT Round-Trip Time

[0178] SCG Secondary Cell Group

[0179] SCMA Single-Carrier Multiple Access

[0180] SCS Subcarrier Spacing

[0181] SDU Service Data Unit

[0182] SOM Spectrum Operation Mode

[0183] SP Semi-Persistent

[0184] SpCell The primary cell of the primary or secondary cell group.

[0185] SRB Signaling Radio Bearer

[0186] SS Synchronization Signal

[0187] SRS Sounding Reference Signal

[0188] SSS Supplementary Synchronization Signal

[0189] SUL Supplementary Uplink

[0190] SWG Switching Gap (in stand-alone subframes)

[0191] TB Transport Block

[0192] TBS Transport Block Size

[0193] TCI Transmission Configuration Index

[0194] TDD Time Division Duplexing

[0195] TDM Time Division Multiplexing

[0196] TI Time Interval (in integer multiples of one or more symbols)

[0197] TTI Transmission Time Interval (in integer multiples of one or more symbols)

[0198] TRP Transmission / Reception Point

[0199] TRPG Transmission / Reception Point Group

[0200] TRS Tracking Reference Signal

[0201] TRx Transceiver

[0202] UL Uplink

[0203] UE User Equipment

[0204] URC Ultra-Reliable Communication

[0205] URLLC Ultra-Reliable and Low-Latency Communication

[0206] V2X Vehicle-to-Everything Communication

[0207] WLAN Wireless Local Area Network and related technologies (IEEE 802.xx domain)

[0208] WTRU Wireless Transmission / Reception Unit

[0209] The beam failure recovery process for New Radio (NR) is described herein. During the beam failure recovery (BFR) process, the WTRU may continuously monitor a set of WTRU-specific periodic reference signals (RSs) associated with the beam used for the Physical Downlink Control Channel (PDCCH), such as Synchronization Signal Blocks (SSBs) (also referred to herein as SS / PBCH blocks) and / or Channel State Information Reference Signals (CSI-RSs). In particular, for each Bandwidth Part (BWP) of a serving cell, a set of periodic CSI-RS resource configuration indices and / or SS / PBCH block indices (which may be referred to as the set) )。A set of resource configuration indices or SS / PBCH block indices can be indicated in a message including one or more parameters such as failureDetectionResources. If no RS is provided for the purpose of beam failure detection, the WTRU can perform beam monitoring based on the set of RSs indicated by or associated with the active TCI state used for PDCCH reception. If there are two RSs associated with the TCI state, the set can include RS indices that have a QCL-TypeD configuration for each respective TCI state. When the measured beam quality of all WTRU-specific periodic RS sets falls below a threshold multiple times (e.g., the number of times defined by a message or parameter such as beamFailureInstanceMaxCount) within a time interval (e.g., defined by a message or parameter such as beamFailureDetectionTimer), the WTRU can declare a beam failure and initiate a beam failure recovery procedure to identify alternative candidate beams. The beam failure recovery procedure can be subject to a timer (e.g., a time duration defined by a message or parameter such as beamFailureRecoveryTimer).

[0210] Alternative candidate beams can be from a set of WTRU-specific periodic RSs (e.g., SSB and / or CSI-RS) Selected from, the set can be configured by a message including parameters such as candidateBeamRSList or candidateBeamRSListExt or candidateBeamRSSCellList. Such parameters can be indicated via a radio resource control (RRC) configuration message or another logically equivalent message. After finding a new beam, the WTRU can transmit messages such as beam recovery requests and / or beam failure indications to the base station via a dedicated physical random access response channel (PRACH). For this purpose, the base station can determine candidate beams based on the association between the PRACH resources and the periodic CSI-RS configuration index and / or the SS / PBCH block index. After receiving the PRACH transmission, the base station can transmit a recovery response message to the WTRU. For example, a dedicated resource set (such as a CORESET) can be provided to the WTRU, for example, an indication of a search space set provided by a parameter such as recoverySearchSpaceId. Such RRC configuration information can be used to monitor PDCCH transmissions in the CORESET. The base station can transmit PDCCH transmissions via the CORESET to confirm the new beam selection. If the response is successfully received by the WTRU, the beam recovery process can be considered successful, and a new beam pair link can be established. Otherwise, the WTRU can perform additional beam recovery requests by ramping up the transmission power of the PRACH transmission. If this still fails, the WTRU can initiate a contention-based RACH process, which may include cell reselection.

[0211] A beam failure recovery process for higher frequency communications (e.g., communications in FR2-2) is described herein. Higher frequency communications may be more susceptible to path loss than communications at lower frequencies. To compensate for the higher path loss, the antenna gain is increased, which may result in highly directional narrow beams. When using narrow beams, even small movements of the WTRU and / or rotation or movement of an object blocking the radio wave propagation may render multiple candidate beams unsuitable for beam failure recovery. Taking this into account, if the candidate beams are semi-statically configured (as may be common in Rel-16 / 17), many candidate beams can be configured to ensure that the WTRU can find a new beam with sufficient quality in case of a beam failure. If the WTRU is unable to find a new beam with sufficient quality, the WTRU may experience frequent radio link failures (RLFs). However, if many candidate beams are used, the throughput may degrade because the transmissions sent using the candidate beams are transmitted in a TDM manner. This may result in excessive overhead of time / frequency resources. In addition, monitoring many candidate beams may be problematic for battery-powered user terminals due to the increased power consumption.

[0212] Several extensions are proposed in this document to provide a more efficient beam failure recovery process, which is more suitable for higher frequency communications. These extensions can include making the candidate beam set dynamic and improvements in using AI / ML-based beam prediction in the candidate beam determination process.

[0213] The various problems solved by the embodiments in this document are described below. Determining candidate beams based on past and current beam measurements may not be an efficient means of operation for dynamic beam-based communication systems such as NR. For this reason, some of the methods proposed in this document can involve AI / ML-based beam prediction, which can be used to predict future requirements / conditions. With such capabilities, candidate beam resources can be selected considering past, current, and predicted future requirements / conditions. To make this possible, several design issues may need to be overcome. These can include, but are not limited to: (1) how the AI / ML-based beam prediction capabilities can be used in the candidate beam determination process; (2) how the base station (or WTRU) determines to activate / deactivate AI / ML-based candidate beam determination and indicates activation / deactivation to the WTRU (or base station); (3) how the base station (or WTRU) monitors the performance of the AI / ML-based candidate beam set and determines the need for a new candidate beam set; (4) how the base station (or WTRU) monitors the accuracy of the AI / ML-based candidate beam set determination, identifies the need for AI / ML model training, and triggers or requests AI / ML model training; and (5) how the base station (or WTRU) determines candidate beams and indicates the determined candidate beam set to the WTRU (or base station).

[0214] In some solutions, group-based candidate beam set indication / configuration can be supported. For example, this can enable the dynamic configuration of candidate beam sets with manageable signaling overhead. To utilize the candidate beam determination process, several design issues need to be addressed. These include, but are not limited to: (1) how the group-based candidate beam configuration can be used to enhance the AI / ML-assisted candidate beam determination process; and (2) how to determine BFR-related parameters when using group-based candidate beam configuration.

[0215] Another design issue associated with BFR may be how to select a suitable set of BFD-RS. To make this possible, several further design issues may need to be addressed. These can include, but are not limited to: (1) how the WTRU can dynamically determine / configure a set of BFD-RS; and (2) how the WTRU can dynamically determine / configure BFD-related parameters.

[0216] Proposed solutions that can solve one or more of the above problems are described herein. Some solutions can enable a WTRU to be configured for a dynamic candidate beam set and perform BFR using the dynamic candidate beam set. Some solutions can enable a WTRU to be configured for a dynamic candidate beam set of a first type of beam (e.g., an FR2 beam) and perform BFR using the dynamic candidate beam set of the first type of beam (e.g., an FR2 beam) based on beam predictions and / or measurements associated with a second type of beam (e.g., an FR1 beam). Some solutions can enable a WTRU to be configured with a candidate beam set that includes candidate beams that are best in terms of measured and / or predicted beam quality (e.g., L1-RSRP) with a configured probability level. Some solutions can enable a WTRU to be configured with a dynamic candidate beam set and perform BFR using the dynamic candidate beam set based on predictions and / or measurements of one or more beam quality parameters (e.g., PMI, CQI, RI, L1-RSRP, SINR, RSRQ). Some solutions can enable a WTRU to be configured with a dynamic candidate beam set and perform BFR using the dynamic candidate beam set based on the location and / or time of the WTRU. Some solutions can enable a WTRU to determine the availability of a candidate beam set for a secondary cell based on current beam quality measurements and / or predicted beam quality within a future time interval.

[0217] A "beam" can be defined or understood as follows. A radio beam can be conceptualized as a stream of concentrated radio waves pointing in a specific direction. A beamforming transmission with a direction and narrowness can be generated, and the direction and narrowness can be controlled to target a specific receiver or area, thus allowing for efficient use of the radio spectrum and reducing interference with other transmissions. A WTRU can transmit or receive a physical channel or reference signal according to at least one spatial domain filter. Thus, the term "beam" can be used to refer to the spatial domain filter used to send a transmission in a beamforming mode.

[0218] A WTRU can derive transmission beamforming parameters based on reception parameters. A WTRU can use the same spatial domain filter as the one used for receiving an RS (such as a CSI-RS) or a synchronization signal (SS) block to transmit a physical channel transmission or signal. The WTRU transmission can be referred to as the "target", while the received RS or SS block can be referred to as the "reference" or "source". In such a case, it can be said that the WTRU transmits the target physical channel or signal based on the spatial relationship of referring to such an RS or SS block.

[0219] In some examples, the WTRU may transmit a first physical channel transmission or signal according to the same spatial domain filter as the spatial domain filter used for transmitting a second physical channel or signal. The first and second transmissions may be referred to as "target" and "reference" (or "source"), respectively. In such a case, it may be said that the WTRU transmits the first (target) physical channel or signal according to the spatial relationship of the reference second (reference) physical channel or signal.

[0220] The spatial relationship may be implicit or configured or signaled via messaging (e.g., RRC, MAC-CE, or DCI). For example, the WTRU may implicitly determine the transmission of the PUSCH transmission and the DM-RS using the PUSCH according to the same spatial domain filter as the one used for transmitting the SRS. The WTRU may determine the spatial domain filter as the spatial domain filter indicated by n SRS resource indicators (SRIs) carried in a message such as DCI or configured by RRC. In some examples, the spatial relationship may be configured by RRC for the SRI or signaled by MAC-CE for PUCCH transmission. Such a spatial relationship may also be referred to as "beam indication".

[0221] The WTRU may receive a first (target) downlink channel or signal according to the same spatial domain filter or spatial reception parameter as a second (reference) downlink channel or signal. For example, such an association may exist between a physical channel such as a PDCCH or a PDSCH and its corresponding DM-RS. In some cases, such as when the first and second signals are reference signals, an association may exist when the WTRU is configured with a quasi-co-location (QCL) assumption type D between corresponding antenna ports. Such an association may be configured as a transmission configuration indicator (TCI) state. The WTRU may receive an indication of the association between a CSI-RS or an SS block and a DM-RS. The indication may be provided by an index associated with a set of TCI states configured by RRC and / or signaled by MAC-CE. Such an indication may also be referred to as "beam indication".

[0222] Figure 2 is a Venn diagram representation of a set of candidate beam sets and active candidate beams of the set of candidate beam sets. As Figure 2 shown, the candidate beam set 200 is represented by In the description of the examples provided herein, candidate beam grouping may be used, substantially as Figure 2 shown. That is, the configured candidate beams may be grouped to create N subsets of the candidate beam set, which are represented by Accordingly, a particular beam or grouping of beams within A beam group can contain multiple beams or just a single beam. Figure 2 As further shown in, for example, The WTRU configured to perform the BFR procedure may further be configured with a set of active candidate beams of the candidate beam set, which may have common beams (e.g., one or more beams belonging to one subset of the candidate beams may also belong to one or more other subsets of the candidate beams). Figure 2 is represented as For example, the WTRU may receive an indication from a base station, and / or the WTRU may determine a selected set of candidate beam groups to be activated at one time, i.e. (In Figure 2 In the example configuration shown in , S Active ∈{2,4}). The WTRU may use The candidate beam(s) or beam sets(s) represented by the active beam(s) are used to perform BFR.

[0223] Examples of group-based candidate beam set indication and determination / configuration of BFR-related parameters are described herein.

[0224] The WTRU may substantially perform the following operations with respect to the active candidate beam set: In some examples, the WTRU may receive a candidate beam set. In some cases, the WTRU may receive configuration information indicating For example, the WTRU may receive information indicating a subset of the beams in the beam set. In some cases, the WTRU may receive information to activate or deactivate group-based candidate beam determination. For example, the information to activate or deactivate group-based candidate beam determination may be a 1-bit indication carried via MAC-CE or DCI, although it is conceivable that other messaging may be used.

[0225] When the WTRU receives only Rather than When the WTRU is instructed to All candidate beams of The WTRU may use BFR is performed as a candidate beam resource set for BFR.

[0226] When the WTRU is configured with a subset of beams but is not configured to perform active group-based candidate beam determination When Execute BFR using the candidate beam resource set as the BFR.

[0227] If the WTRU receives information and an indication for activating group-based candidate beam determination and the configuration information, and a set of selections of candidate beams or beam groups, i.e., then the WTRU may use the active candidate beams represented by to perform BFR (e.g., CFRA-BFR), where

[0228] Examples of BFR-related parameter determination are described in the following paragraphs. In some examples, the WTRU may determine one or more beam failure recovery-related parameters based on the configuration parameters for . These BFR-related parameters may include, but are not limited to, a time duration or a timer (e.g., beamFailureRecoveryTimer), a threshold for beam quality assessment (e.g., rsrp-ThresholdSSB or rsrp-ThresholdBFR), different priority configurations (e.g., prioritization / ra-PrioritizationTwoStep), a transmission power / power ramp parameter for transmitting BF indication (e.g., transmission power / power ramp step for transmitting a preamble associated with a new beam).

[0229] In some examples, the WTRU may first receive BFR-related parameters for (e.g., via one or more RRC configuration messages or via other logically equivalent signaling). The WTRU may then receive configuration information for one or more BFR-related parameters (e.g., via MAC-CE or DCI, or other logically equivalent messages). When configured, the BFR-related parameters for configured in the second step may override the parameters for configured in the first step.

[0230] In some examples, when the WTRU is configured with one for the candidate beam set, i.e., S Active whose cardinality is 1 (|S Active | = 1), the WTRU may perform BFR based on the parameters associated with the configured . If the WTRU is configured with more than one for BFR, i.e., |S Active | > 1, then the WTRU may consider the parameters associated with all beams or consider the parameters associated with the beams selected by Determine BFR-related parameters based on the parameters associated with the indicated specific beam.

[0231] In some example configurations, the WTRU may be configured with and (S Active ∈ {1, 2}), each having different timing parameters or time durations (e.g., timer1 and timer2). In such a case, the WTRU may perform BFR, assuming and determine that the time duration is the minimum of the configured time parameters (i.e., where timer = min{timer1, timer2}). Alternatively or additionally, the WTRU may be configured to determine the time duration based on the maximum of the configured time parameters (i.e., where timer = max{timer1, timer2}).

[0232] In some solutions, the WTRU may receive priority information associated with each of the indicated beams . When determining BFR-related parameters, the WTRU may give priority to the parameters associated with the higher-priority beam. For example, a scenario may involve a beam set with two active beams (i.e., S Active ∈ {1, 2}). In such a case, may be associated with a first parameter (e.g., the time duration defined by timer1), while may be associated with a second parameter (e.g., the time duration defined by timer2). The WTRU may receive configuration information indicating that has a higher priority than . In such a scenario, the WTRU may utilize to perform BFR and utilize the time duration indicated by timer2 based on the higher priority.

[0233] Solutions for BFR utilizing are described in the following paragraphs. In some solutions, the WTRU may use to perform the BFR process (e.g., find new candidate beams and utilize CFRA to indicate the determined new candidate beams) and use one or a combination of the following steps to determine BFR-related parameters.

[0234] The WTRU may monitor The beam quality of the candidate beam resources (e.g., L1-RSRP, SINR, or another beam quality metric). For example, when a beam failure or one or more beam failure instances are detected, the WTRU may initiate monitoring of candidate beams. Alternatively, the WTRU may monitor candidate beams periodically. The period of beam monitoring may be configured by the base station. For example, the monitoring period may be configured as the period of the beam, where a is dynamically indicated via MAC-CE or DCI or other logically equivalent message passing. The default value of a (e.g., a = 1) may be configured, for example, using RRC message passing or another logically equivalent.

[0235] The WTRU may select a beam as a new beam (e.g., the beam with the highest measured quality) based on the measured beam quality (e.g., L1-RSRP, SINR, or another beam quality metric). The WTRU may indicate its selection to the base station.

[0236] The WTRU may indicate the beam failure and indicate its selected new beam by transmitting a preamble corresponding to that beam (e.g., associated with a preamble occasion selected from ). The WTRU may monitor the BFR-CORESET to obtain confirmation from the base station. In the case where the WTRU receives confirmation from the base station of the transmission of the preamble transmitted using the selected beam, the WTRU may select a new beam for subsequent transmission / reception and terminate the BFR process.

[0237] In the case where the WTRU does not receive confirmation within the monitoring window duration (which may be determined using a BFR parameter determination process substantially as described in the above paragraphs), the WTRU may attempt to retransmit the preamble after increasing the transmission power. The WTRU may determine the increase in transmission power based on a BFR-related parameter determination process substantially as described in the above paragraphs. In the case where the WTRU fails to receive confirmation of its new beam selection after multiple attempts to retransmit, the WTRU may perform CBRA-BFR. The WTRU may receive configuration information indicating a limit on the number of attempts to retransmit, or may implicitly derive a limit on the number of attempts to retransmit.

[0238] In some cases, if the WTRU determines that no beam in satisfies the beam quality threshold measurement, the WTRU may perform CBRA-BFR.

[0239] Described herein are methods for determining the active candidate beam set AI / ML-assisted methods. In at least some of the methods proposed herein, an active candidate beam set can be determined for FR2 via beam prediction based on FR1 beams. The configuration of candidate beam subsets and associated beams across frequency ranges is described in the following paragraphs.

[0240] In some examples, the WTRU can be configured with a set of first beams that includes all possible candidate beams. Optionally or additionally, the WTRU can be configured with one or more subsets of the set of first beams. A subset of beams can include one or more beams Consistent with the description of the examples herein, a "subset" or "group" of beams can conceivably represent a single beam.

[0241] The WTRU can be configured with an association between one or more subsets of beams and one or more beam resource sets. The (one or more) beam resource sets can point to resources located in a frequency region different from the frequency region (FR) in which the beam operates. For example, the WTRU can be configured with a subset of one or more beams in FR2, and each subset of beams in FR2 can be associated with a beam resource set in FR1. The FR1 beam resources can be associated with one or more FR2 beams or subsets of beams.

[0242] The configuration of the (one or more) subsets of beams, the beam resource configuration, and the association between beams of different FRs can be received by the WTRU via dynamic (e.g., L1 or MAC or other logically equivalent) signaling or semi-static (e.g., RRC) signaling. In some methods, the WTRU can determine the association between a subset of beams in a first FR and beam resources in a second FR. The WTRU can send an indication of the association to the base station, for example, via dynamic (e.g., L1 or MAC) signaling or semi-static (e.g., RRC) signaling.

[0243] Examples of methods involving blockage prediction are described in the following paragraphs.

[0244] In some examples, the WTRU can determine whether a beam or a subset of beams will be obstructed. Obstruction can include at least one of the following: blockage, poor performance (e.g., HARQ performance), fast or slow fading, changes in AoA / AoD, switching from LoS to NLoS (or vice versa), or changes in signal quality (such as SINR or RSRP or RSRQ or CQI). Although the various examples herein may specifically relate to blockage or blockage probability, it should be understood that such examples can apply to any other type of obstruction.

[0245] The WTRU may perform blockage prediction on one beam, a subset of one or more beams, or all beams. In some examples, blockage prediction may refer to determining that one beam, a subset of beams, or all beams are suffering from blockage. This may include the start time of the blockage and the predicted duration or end time of the blockage. Blockage prediction may refer to determining that one beam, a subset of beams, or all beams will suffer from blockage. Blockage prediction may involve determining the predicted start time, duration, and / or end time of the blockage. Blockage prediction may include determining that one beam, a subset of beams, or all beams may suffer from blockage. Blockage prediction may include determining the probability that one beam, a subset of beams, or all beams may suffer from blockage. This may include one or more blockage probabilities, each associated with a different time instance, where the time instance may include symbols, a set of time slots, or may be defined by another time interval.

[0246] The WTRU may be configured with an AI / ML model to perform blockage prediction. For example, the WTRU may be configured to perform localized computations to apply and integrate the AI / ML model without causing latency to the network. For example, this may enable faster beam management and beam selection decisions in communications using higher frequencies (where a large number of beams are used). The WTRU and / or the network may be configured to retrain the AI / ML model periodically (or on request) using data collected by the WTRU, by other WTRUs, or by the network. Alternatively, in some cases, a network node (such as a base station, a core network node, or another network entity) may be configured to perform the AI / ML model for blockage prediction.

[0247] The WTRU may perform blockage prediction on one beam, a subset of beams, or all beams using one or more beam resources (or a set of beam resources). The set of beam resources for blockage prediction may be in the same FR as the FR configuring the associated beam (e.g., FR2), or the set of beam resources for blockage prediction may be in a different FR from the FR configuring the associated beam (e.g., the resource set is in FR1 and a subset of beams is configured with FR2). The WTRU may perform blockage prediction on a subset of beams on a first beam resource (or a set of beam resources) in a first FR and a second beam resource (or a set of beam resources) in a second FR.

[0248] The WTRU may perform blockage prediction using various parameters. The parameters may be configured (e.g., via RRC signaling or other logically equivalent signaling) or indicated (e.g., via DCI or MAC-CE or other logically equivalent messages). The parameters may include one or more of a period and / or time offset information. For example, the WTRU may perform periodic blockage prediction using a configurable period and / or time offset. The period and / or time offset for blockage prediction may be determined based on a period and / or time offset associated with a beam resource (e.g., a beam resource set), or based on a resource for feedback of blockage prediction.

[0249] The parameters for blockage prediction may include the duration of the blockage. For example, the WTRU may be configured with a minimum amount of time that a blockage may be detected before the WTRU may declare that a blockage has been predicted. For example, the amount of time may be measured according to known time metrics such as symbols, time slots, or milliseconds or frames / sub-frames. For example, if a hypothesized blockage is determined, predicted, or measured to last for at least x milliseconds, the WTRU may declare that a blockage has been predicted.

[0250] The parameters for blockage prediction may include an admissible blockage probability threshold. For example, the WTRU may be configured with a maximum admissible blockage probability threshold above which the WTRU may declare that a blockage has been predicted. In other words, if the WTRU determines that a blockage may occur at a level of probability that exceeds the admissible blockage probability threshold, the WTRU may declare that a blockage has been predicted.

[0251] The parameters for blockage prediction may include an admissible blockage duration threshold. For example, the WTRU may be configured with a maximum admissible blockage duration threshold above which the WTRU may declare that a blockage has been predicted. In other words, the admissible blockage probability threshold may define the length of time that a predicted blockage may not trigger the WTRU to declare that a blockage has been predicted.

[0252] The parameters for blockage prediction may include a blockage prediction confidence threshold. The confidence threshold may be a predefined limit or value that may be used to determine whether a blockage prediction may be considered reliable or actionable. For example, if a blockage prediction is made at a confidence level that exceeds the configured confidence threshold, the WTRU may confirm its classification of the blockage prediction. On the other hand, if a blockage prediction is made at a confidence level that does not reach the configured confidence threshold, the WTRU may be configured not to declare that a blockage has been predicted.

[0253] Parameters for blockage prediction can include a validity time period. For example, a WTRU may determine that a subset of beams is in valid use (i.e., not suffering from blockage), and the validity may be associated with a validity time period. Alternatively or additionally, the validity time may be configured to apply to beam blockage prediction such that a prediction that one or more beams are experiencing blockage or will experience blockage in the future is only valid during the validity time period.

[0254] Parameters for blockage prediction can include activation and / or deactivation criteria. For example, a WTRU may receive an activation (or deactivation) indication to start (or stop) monitoring one or more beams, a subset of one or more beams, or all beams for blockage prediction. In some examples, a WTRU may determine to start (or stop) monitoring one or more beams, a subset of one or more beams, or all beams for blockage prediction based on at least one of the following: measurements (e.g., RSRP, SINR, RSRQ, RSSI, CO, CQI, RI, PMI, delay spread, Doppler spread, average delay, average Doppler, AoA / AoD, LOS / NLOS, or another metric), the time duration since the last or previous blockage prediction (or its time instance), a change in the beam set, mobility, speed, location, the priority of data in a buffer, activation / deactivation of a carrier, a change in BWP, or activation / deactivation / configuration / trigger information associated with (one or more) beam resources or (one or more) beam resource sets, or (one or more) resources for reporting beam measurements and / or blockage predictions.

[0255] Methods for selecting beams (e.g., a subset of beams) from an active candidate beam set are described herein.

[0256] In some examples, a WTRU may be configured with a subset of multiple beams. The WTRU may determine an active candidate beam set according to one or more methods described herein. The active candidate beam set may refer to the beams (or associated measurement resources) that a WTRU can monitor or perform measurements on when suffering from a beam failure on one or more beams. The WTRU may determine the active candidate beam set as a union, concatenation, and / or superset of a subset of one or more beams. The active candidate beam set may include a subset of a first beam set (which may cover all possible candidate beams).

[0257] If one or more beams or a subset of beams satisfy one or more of the following criteria, the WTRU may determine that one or more beams or a subset of beams may be included in the active candidate beam set. Those skilled in the art should understand that the foregoing list of criteria is not exhaustive, and the active candidate beam set may be determined based on other criteria not listed in the immediately following paragraphs.

[0258] Examples of criteria can be that the blocking probability is below a threshold. For example, the blocking probability of a subset of beams can be determined as the average or maximum or minimum of the blocking probabilities of the beams in the subset of beams.

[0259] Examples of criteria can be that a subset of beams has at least x beams that meet the blocking probability threshold, where x can be configurable, and / or where meeting the blocking probability threshold can mean that the blocking probability of the beam is less than the blocking probability threshold.

[0260] Examples of criteria can be that a subset of beams has the most beams that meet the blocking probability threshold. For example, a WTRU can be configured with a subset of multiple beams, and the WTRU can select an active candidate set that includes the subset of beams that has the most beams whose blocking probability is less than the blocking probability threshold.

[0261] Examples of criteria can be that the subset of beams to be included in the active candidate beam set includes one or more "best" beams. For example, the WTRU can select one or more "best" beams for each configured subset of beams, and the active candidate beam set can include the union of these "best" beams. In some cases, the "best" beam can be determined as the beam with the lowest blocking probability. The "best" beam can be determined as the beam with the minimum blocking duration. The "best" beam can be determined as the beam that has not experienced blocking, is not currently experiencing blocking, and / or is predicted not to experience blocking.

[0262] Examples of criteria can be that the blocking duration is below a threshold. In some examples, such as when the subset includes multiple beams, the blocking duration of a subset of beams can be determined as the average or maximum or minimum of the blocking durations of the beams in the subset of beams.

[0263] Examples of criteria can be that a subset of beams has at least x beams that meet the blocking duration threshold, where x can be configurable, and / or where meeting the blocking duration threshold can mean that the blocking duration of the beam is less than the blocking duration threshold.

[0264] Examples of criteria can be that a subset of beams has the most beams that meet the blocking duration threshold. For example, a WTRU can be configured with a subset of multiple beams, and the WTRU can select an active candidate beam set that includes the subset of beams that has the most beams whose blocking duration is less than the blocking duration threshold. Another example of a criterion can be that the selected subset of beams or the selected beams meet a prediction confidence threshold.

[0265] The triggering for selecting a new active candidate beam set is described herein. A WTRU may be configured with an active candidate beam set, and the WTRU may select a new active candidate beam set when triggered to do so. In some examples, the new active candidate beam set may be the same as the previous active candidate beam set.

[0266] The WTRU may be triggered to select a new active candidate beam set based on various conditions or events. In some examples, the WTRU may be triggered to select a new active candidate beam set at a given time. For example, the WTRU may select a new active candidate beam set at a time instance determined based on a period and / or offset value. The period and / or offset value may be configurable or may be implicitly derived.

[0267] The WTRU may be triggered to select a new active candidate beam set set by the base station. The WTRU may receive a trigger indication from the base station to obtain the new active candidate beam set. The trigger indication may be received via signaling such as DCI, MAC-CE, RRC, or other logically equivalent signaling. The trigger indication may be received implicitly and / or may be assumed when another signal is received that provides information such as a beam change indication, HARQ-ACK feedback, cell activation / deactivation indication, BWP change indication, handover command, or system information.

[0268] The WTRU may be triggered to select a new active candidate beam set based on a validity time period. For example, if the validity time period of the previous active candidate beam set has passed, the WTRU may select a new active candidate beam set. The validity time may be measured in symbols, time slots, or milliseconds.

[0269] The WTRU may be triggered to select a new active candidate beam set based on measurements of the current or previous active candidate beam set. For example, the WTRU may perform measurements on at least one beam of the current or previous active candidate beam set (or on at least one measurement resource associated with one of the beams in the active candidate beam set). The WTRU may determine that one or more beams or a subset of beams in the current or previous active candidate beam set are no longer valid based on the at least one measurement value. For example, the WTRU may track blocking conditions such as the blocking probability or the duration or timing of the beams in the active candidate beam set. If the blocking condition deteriorates (e.g., the blocking probability, duration, or timing becomes worse than allowed), the WTRU may be triggered to select a new active candidate beam set. In some examples, if more than Y beams or a subset of beams in the active candidate beam set have a blocking probability or duration greater than a threshold, the WTRU may be triggered to select a new active candidate beam set. In the foregoing example, Y may be configurable or may be determined, for example, based on the size of the active candidate beam set.

[0270] The WTRU can be triggered to select a new active candidate beam set based on the metrics of a subset of beams. For example, the WTRU can maintain metrics or measurements associated with one or more beams or subsets of beams included in the current active candidate beam set and outside the current active candidate beam set. If the metrics (e.g., blockage probability, blockage duration) or measurement values (e.g., SINR, RSRP, RSSI, RSRQ, CQI, RI, PMI, AoA / AoD, delay spread, Doppler spread, average delay, average Doppler, CO) associated with one or more beams or subsets of beams (e.g., a subset of beams not included in the active candidate beam set) become greater than or less than the metrics or measurement values of the current active candidate beam set or a subset of beams in the current active candidate beam set, the WTRU can be triggered to select a new active candidate beam set. For example, if the metrics or measurement values associated with one or more beams or subsets of beams are larger or smaller by an offset value than the corresponding metrics or measurement values associated with the current active beam set, the WTRU can be triggered to select a new active candidate beam set. The offset value can be selected by the WTRU, configured by the WTRU, or implicitly derived.

[0271] Indications regarding the active candidate beam set are described herein. The WTRU can indicate to the base station that the active candidate beam set is no longer valid. For example, when a trigger for selecting a new active candidate beam set (listed above) is satisfied, the WTRU can indicate to the base station that the active candidate beam set is no longer valid. This indication can be provided via UCI, PRACH transmission (e.g., preamble), PUSCH transmission, PUCCH transmission, MAC-CE, RRC signaling, SRS transmission, PRS transmission, or another logically equivalent transmission.

[0272] The WTRU can indicate to the base station that it has selected a new active candidate beam set. For example, when selecting a new active candidate beam set, the WTRU can indicate the new active candidate beam set to the base station. This indication can be provided via UCI, PRACH transmission (e.g., preamble), PUSCH transmission, PUCCH transmission, MAC-CE, RRC signaling, SRS transmission, PRS transmission, or another logically equivalent transmission.

[0273] The WTRU may indicate to the base station that the active candidate beam set remains unchanged. For example, the WTRU may periodically report to the base station whether it has been triggered to select a new active candidate beam set. If the WTRU has not selected a new active candidate beam set, the WTRU may report that the set has not changed. If the WTRU has selected a new active candidate beam set, the WTRU may report that the set has changed along with the parameters of the new active candidate beam set. This indication may be provided via UCI, PRACH transmission (e.g., preamble), PUSCH transmission, PUCCH transmission, MAC-CE, RRC signaling, SRS transmission, PRS transmission, or another logically equivalent transmission.

[0274] When the WTRU indicates that a new active candidate beam set has been selected, the WTRU may include one or more of the information described in the following paragraphs. In some examples, the WTRU may include the time of activation of the new active candidate beam set or deactivation of the previous set.

[0275] In some examples, the WTRU may include the content of the active candidate beam set. The content may include a subset of one or more beams, and the union of the subset of beams forms the active candidate beam set. The content of the active candidate beam set may be indicated via an index associated with a subset of at least one beam in the active candidate beam set.

[0276] In some examples, the WTRU may include measurements or metrics associated with a subset of beams in the active candidate beam set. For example, the WTRU may include a blockage prediction associated with one or more beams or subsets of beams that make up the active candidate beam set. The WTRU may determine and report a blockage prediction associated with the active candidate beam set as a whole.

[0277] In some examples, the WTRU may include an index associated with a subset of one or more beams or beams in the active candidate beam set that meet a specific metric. For example, the WTRU may report the index of the beam or subset of beams in the active candidate beam set that has the lowest blockage probability or shortest blockage duration. For example, the WTRU may report the index associated with the beam in the subset of beams in the active candidate beam set that has the lowest blockage probability or shortest blockage duration.

[0278] In some examples, the WTRU may include an index associated with one or more beams or subsets of beams that do not meet the selection criteria. For example, a subset of beams may be included in the active candidate beam set. The WTRU may report the index associated with the beam in the subset of beams that does not meet the required blockage probability or blockage duration threshold.

[0279] In some examples, when selecting an active candidate beam set, the WTRU may immediately assume that the active candidate beam set is activated. In some methods, the WTRU may need to receive confirmation from the base station before assuming that the active candidate beam set is activated.

[0280] Processes for monitoring beams in an active candidate beam set are described herein. It may be assumed that the WTRU can monitor at least one beam in the active candidate beam set. Monitoring may include performing one or more measurements on resources associated with the beam. Resources associated with the beam may be in the same or a different FR as the beam. The WTRU may be triggered to monitor at least one beam in the active candidate beam set. The trigger that causes the WTRU to monitor at least one beam in the active candidate beam set may include one or more examples described in the following paragraphs.

[0281] An example of a trigger that causes the WTRU to monitor at least one beam in the active candidate beam set may be detecting a beam failure on at least one or all of the used (or activated) beams.

[0282] An example of a trigger that causes the WTRU to monitor at least one beam in the active candidate beam set may be receiving a trigger (e.g., a message, signal, or transmission from the base station).

[0283] An example of a trigger that causes the WTRU to monitor at least one beam in the active candidate beam set may be a measurement of at least one of the used (or activated) beams. For example, when the blockage prediction for at least one of the used (or activated) beams drops below a threshold, the WTRU may be triggered to monitor at least one beam in the active candidate beam set.

[0284] An example of a trigger that causes the WTRU to monitor at least one beam in the active candidate beam set may be a periodic trigger. For example, the WTRU may periodically monitor the beams in the active candidate beam set with a configurable period and offset.

[0285] The WTRU may select a beam in the active candidate beam set for which or against which beam failure recovery is to be performed. The selection of the beam for which or against which beam failure recovery is to be performed may be based on at least one of several criteria. The criteria may include measurements such as the highest RSRP (e.g., L1-RSRP) of all beams in the active candidate beam set; measurements such as RSRP (or L1-RSRP) above a threshold; the lowest blockage probability or duration of all beams in the active candidate beam set; a blockage probability or duration below a threshold; whether the monitoring or measurement is performed on resources in the same or a different FR; a blockage prediction below or above a threshold; or a confidence value of the blockage prediction.

[0286] The selection of the beam for which or against which beam failure recovery is to be performed can be based on an identifier associated with a subset of beams to which the beam belongs. For example, the WTRU can select a beam from a subset of the selected beams. The subset of the selected beams can meet at least one criterion. The subset of the selected beams can be a subset of beams from beams that are not currently in use (or active). The subset of the selected beams can be a subset of beams from at least one beam that is in use (or active). The subset of the selected beams can be a subset of beams to which the beam that has suffered a beam failure belongs.

[0287] If no beam meets the above criteria, the WTRU can perform CBRA - BFR. If no beam meets the above criteria, the WTRU can be triggered to select a new set of active candidate beams.

[0288] Examples of various methods for determining, for example, based on the probability that each beam is the best beam in a future time interval, or the probability of carrying the best quality beam in a future time interval via beam prediction using FR2 beams, are described herein. of the set.

[0289] The availability of AI / ML models is described herein. In some solutions, the WTRU can be configured to use an AI / ML model to predict the best candidate beam in a future time instance. More generally, the WTRU can use an AI / ML model to predict the likelihood that a beam will become the best candidate beam in a future time instance. In some cases, the WTRU can be configured to predict the best candidate beam at different levels of granularity.

[0290] As described above, in some solutions, the WTRU can predict the best candidate beam in a future time instance. In another solution, the WTRU can predict the best candidate beam set from multiple candidate beam sets or partitions thereof. In one or more of the solutions described herein, the AI / ML model can be configured at the WTRU by one or more of the following methods: the model can be trained by the WTRU; the model can be trained at the network (e.g., at a base station or another network node) and transmitted to the WTRU; the model can be trained at the operation, administration, and maintenance (OAM) and transmitted to the WTRU; or the model can be trained at an external server and transmitted to the WTRU.

[0291] Configuration aspects are described herein. A WTRU may receive from a base station one or more parameters that may be used to perform beam quality prediction. In some solutions, the WTRU may be configured to perform beam quality prediction on multiple candidate beam sets. In some cases, such candidate beam sets may be defined based on a dynamic partitioning of the total number of available beams. In some solutions, the WTRU may be configured to perform beam quality prediction on multiple candidate beams within a pre-configured set of available beams. In some solutions, the WTRU may be configured with a period for beam prediction, e.g., T BP . For example, based on this configuration, the WTRU may perform inference operations associated with beam quality prediction at least every T BP time units. In some solutions, the WTRU may be configured to perform beam quality prediction on each candidate beam set every T BP time units. In some solutions, the WTRU may be configured to perform beam quality prediction on each candidate beam every T BP time units. In some solutions, the WTRU may be configured with a beam prediction validity time T d . The WTRU may perform inference such that the prediction result remains valid for at least T d time units. The WTRU may be configured with one or more FR2 beam resource sets (ψ 2 ) for performing beam measurements. In some cases, the configuration of the FR2 beam resource set may include a period of RS resources for performing beam measurements. The WTRU may use the measurements from the FR2 beam resource set as input to an AI / ML model for prediction. In some solutions, the WTRU may determine T BP based on the period of the FR2 beam resource set. In some solutions, the WTRU may implicitly derive the value of T BP as an integer multiple of the period of the FR2 beam resource set. In some solutions, the WTRU may implicitly derive the value of T d as an integer multiple of the period of the FR2 beam resource set.

[0292] In some solutions, T BP and / or the value of T d may be determined and / or configured according to the capabilities of the WTRU. The time units T BP and / or T d may be expressed in milliseconds, symbols, time slots, subframes, radio frames, or other units.

[0293] In some solutions, the WTRU may be configured with parameters that assist the WTRU in determining the selection of candidate beams or candidate beam sets. For example, the WTRU may be configured to be based on the parameter P sum-targetto select candidate beams. For example, the WTRU may determine the probability that each candidate beam is the best beam at a future time instance. If the sum of the probabilities of the candidate beams within the candidate beam set exceeds P sum-target , the WTRU may select the candidate beam set. For example, if no candidate beam set by itself meets the threshold, the WTRU may select more than one candidate beam set to meet P sum-target criterion.

[0294] In some solutions, the WTRU may be configured with parameters that assist the WTRU in determining the selection of (one or more) candidate beams. For example, the WTRU may be configured to select candidate beams based on parameter P sum-A to select candidate beams. For example, the WTRU may determine the probability that each candidate beam is the best beam at a future time instance. The WTRU may select candidate beams such that the probability associated with the candidate beams exceeds P sum-A . If no single candidate beam meets the threshold, the WTRU may select two or more candidate beams such that the sum of the probabilities that the candidate beams are the best beams at a future time instance exceeds P sum-A .

[0295] Activation / deactivation of beam quality prediction is described herein. In some solutions, the WTRU may receive an indication from the base station to activate or deactivate beam quality prediction for candidate beams and / or candidate beam sets. For example, the WTRU may perform beam quality prediction associated with candidate beams until deactivated. In another solution, the WTRU may receive an indication from the base station to activate AI / ML-based candidate beam prediction for a configured number of times. In some solutions, when an FR2 beam resource set is configured, the WTRU may perform beam quality prediction. For example, when the FR2 beam resource set is released, the WTRU may deactivate beam quality prediction. In some solutions, the WTRU may perform blockage prediction of candidate beams until a duration has passed or until a preconfigured timer expires. In some cases, the WTRU may implicitly determine the duration or the preconfigured timer value based on a semi-persistent configuration associated with the FR2 beam resource set. In some solutions, beam quality prediction may be implicitly deactivated by configuring the value of T d to zero.

[0296] Selection of a candidate beam subset is described herein. The WTRU may be configured to select a candidate beam subset within multiple candidate beam sets based on preconfigured rules / conditions In some solutions, the WTRU may be configured to select a subset of the beams in based on preconfigured rules / conditions. Such a determination may be based on a future duration Td Beam quality prediction within.

[0297] In some solutions, the WTRU can be configured to select a subset of beams based on criteria determined according to the likelihood of a beam becoming the best beam at a future time T d For example, the WTRU can estimate The probability that each beam in becomes the best beam among all beams. The WTRU can apply an AI / ML model to estimate the probability that a candidate beam is the best candidate beam at a future time. The WTRU can calculate the sum of all probabilities associated with each beam within. In some solutions, if max{P , i ∈ {1, 2,..., N}} ≥ P sum_Si , then the WTRU can select the subset of beams corresponding to the highest estimated probability value P sum-target If max{P sum_Si , i ∈ {1, 2,..., N}} < P If max{P sum_Si , i ∈ {1, 2,..., N}} < P sum-target , then the WTRU can select a subset of more than one beam such that the selected subset in the case of having the lowest number of sets of all the beams in together satisfy P sum-target . In some solutions, the WTRU can be configured with a value P min , the value P min corresponding to the minimum probability that a beam can be considered a candidate beam. When configured with P min , the WTRU can select the subset of beams that includes the highest number of beams whose calculated probabilities are greater than P min Methods for indicating a subset of candidate beams are described herein. In some solutions, the WTRU can be configured to transmit an indication of the selected subset of (one or more) candidate beams to the base station. For example, the WTRU can be configured (e.g., pre-configured) with a subset of candidate beams

[0298] Mapping between a set of RACH resources (e.g., preambles, time, and / or frequency resources). For example, a WTRU may determine RACH resources based on a selected candidate beam set and use the selected RACH resources to transmit a preamble. In some solutions, the WTRU may be configured to transmit an indication of the selected candidate beam set(s) via one or more MAC control elements (MAC-CEs). In some cases, each candidate beam set may be associated with a unique logical identifier. The WTRU may indicate the candidate beam set(s) by transmitting a MAC-CE that includes the logical identifier(s) associated with the selected candidate beam set(s). The indication may include a bitmap, where each bit position may correspond to a candidate beam set. Upon receiving an indication of a selected subset of candidate beams, the base station may update to include only the subset of beams indicated by the WTRU of In response to a candidate beam set indication, the WTRU may receive an acknowledgement from the base station. The acknowledgement may be a function of the indication method. For example, in the case of RACH-based indication, the WTRU may consider a random access response (RAR) corresponding to the transmitted preamble as an acknowledgement of its candidate beam set indication. In the case of MAC-CE-based indication, the WTRU may consider a HARQ-ACK corresponding to the transport block carrying the MAC-CE as an acknowledgement of the candidate beam set indication. Upon receiving a successful acknowledgement, in some cases, the WTRU may consider the indicated beam set as an active candidate beam set Then, the WTRU may use to perform a beam failure recovery process. For example, upon beam failure detection, the WTRU may use beams to perform CFRA-BFR.

[0299] Figure 3 is a diagram illustrating an example of a beam failure recovery process performed by a base station and a WTRU. In the example shown, the WTRU is configured with beam resources in FR1, on which metrics are determined for selecting an active candidate beam set in FR2. At 305, the base station transmits using the beam resource ψ 1 in FR1. At 310, the WTRU monitors the configured beam resource ψ 1 to determine an active candidate beam set for FR2 The WTRU may utilize an AI / ML model to determine an active candidate beam set according to one or more methods substantially described herein. At 315, the WTRU may send an indication of a beam resource or a subset of candidate beam resources selected (e.g., from the beams configured by the parameter candidateBeamRSList) to the base station. As shown at 320, 330, and 340, the base station that has received the indication of the (one or more) beams selected by the WTRU uses the indicated active candidate beam set for transmission in FR2. At 325, the WTRU that has monitored beam failure detection resources determines that a beam failure has occurred. When determining the beam failure and assuming is valid within the duration of T d , the WTRU selects a beam from the active candidate beam set and performs CFRA - BFR, as shown at 335. Subsequently, at 345, at the end of a time period T BP (which may be configured as an integer multiple of the period of ) for beam prediction, the base station may again use the beam resource ψ of FR1 1 for transmission. The WTRU may again monitor the configured beam resource ψ 1 to potentially use an AI / ML model, as shown at 350, to determine an active candidate beam set for FR2

[0300] The process of selecting candidate beams is described herein. In one solution, the WTRU may be configured to select a subset of the beams in based on rules / conditions that may be configured, pre - configured, or implicitly derived. Such selection may be based on beam quality prediction within a future time duration T d . For example, the WTRU may apply an AI / ML model to predict the probability that a candidate beam will become the best beam in the future. For example, the WTRU may rank the candidate beams based on the probability that the candidate beam will become the best beam within a future time interval. Subsequently, the WTRU may select one or more candidate beams such that the minimum number of the highest - ranked beams in (represented as set A) satisfies the criterion that the sum of the probabilities of the beams in set A (the probability that each selected beam is the best beam within the future time interval) (represented by (P sum-A ) is) ≥ the target for the total probability threshold P sum-target .

[0301] Methods for indicating candidate beams are described herein. In some solutions, a WTRU may be configured to transmit an indication of a selected set of candidate beams to a base station. For example, the WTRU may be configured with a mapping between candidate beams and RACH resources (e.g., preambles, time, and / or frequency resources). For example, the WTRU may determine RACH resources based on the selected candidate beams and transmit a preamble via the selected RACH resources. In some solutions, the WTRU may be configured to transmit an indication of the selected candidate beams via one or more MAC control elements (one or more MAC-Ces). Each candidate beam may be associated with a unique logical identifier. The identifier may be a function of an SSBRI (SS / PBCH block resource indicator) and / or a CRI (CSI reference signal resource indicator). The WTRU may indicate the candidate beams by transmitting a MAC-CE that includes one or more logical identifiers associated with the selected candidate beams. The indication may include a bitmap, where each bit position may correspond to a set of candidate beams. In some examples, as Figure 4 shown, upon receiving the indication, the base station may update to include only the beam(s) indicated by the WTRU For example, the WTRU may receive an acknowledgement of the candidate beam indication from the base station. The acknowledgement may depend on the indication method. For example, in the case of RACH-based indication, the WTRU may consider a random access response (RAR) corresponding to the transmitted preamble as an acknowledgement of the candidate beam indication. For example, in the case of MAC-CE-based indication, the WTRU may consider a HARQ ACK corresponding to the TB (transport block) carrying the MAC-CE as an acknowledgement of the candidate beam indication. Upon receiving a successful acknowledgement, the WTRU may consider the beam(s) indicated as a set. The WTRU may then apply and use the set for a beam failure recovery procedure. For example, upon beam failure detection, the WTRU may monitor the beams in the set to perform CFRA-BFR.

[0302] Figure 4 is a diagram illustrating an example of a beam failure recovery procedure performed by a base station and a WTRU. In the example shown, the WTRU is configured to perform FR2 candidate beam prediction based on the characteristics of FR2 beams. As Figure 4 shown, the base station uses beam resources in FR2 (represented by ψ 2 for transmission. As shown at 410, the WTRU may monitor the FR2 beam resource ψ 2 and determine, for FR2, based on the prediction output from an AI / ML model At 415, the WTRU may indicate the selected candidate beam to the base station. The WTRU may indicate the candidate beam or a subset of candidate beams using the methods described herein. As shown at 420, 430, and 440, the base station having received the indication of the beam(s) selected by the WTRU transmits in FR2 using the indicated active candidate beam set. The WTRU may monitor based on a monitoring period The monitoring period can be configured by the base station. The monitoring period can be configured as At 425, the WTRU has monitored the beam failure detection resource and the WTRU determines that a beam failure has occurred. In some solutions, the active candidate beams may be triggered by beam failure detection. At 435, the WTRU may monitor the candidate beam sets. Then at 445, during the period T used for beam prediction, BP (It can be configured as At the end of the period (integer multiples of the period), the base station can use the beam resource ψ of FR2 again. 2 The WTRU may again monitor the configured beam resources ψ 2 , to potentially use an AI / ML model as shown at 450 to determine the active candidate beam set for FR2

[0303] In some examples, during CFRA, the WTRU may select a beam with a measurement quality (e.g., L1-RSRP) that satisfies a first threshold and a predicted blocking probability that does not exceed a second threshold as a new candidate beam. The WTRU indicates a beam failure and its selection of a new beam by transmitting a preamble corresponding to the candidate beam. The WTRU may then monitor the BFR-PDCCH via the BFR-CORESET to confirm the new beam indication. In the event that the WTRU fails to detect the BFR-PDCCH from the base station via the BFR-CORESET to confirm receipt of the new beam indication, the WTRU may repeat the beam indication process using power ramping. If If no beam in satisfies the first threshold, the WTRU may perform CBRA-BFR.

[0304] Described herein are methods for using AI / ML to determine based on predicted metrics of candidate beams such as PMI, CQI and RI, L1-RSRP, SINR, RSRQ The AI / ML model can be trained to determine the beam set based on one or more parameters, including those listed in the following paragraphs. or a subset of active candidates Training of the AI / ML model (i.e., online or offline training) can be performed at the WTRU, and / or at the base station and transmitted to the WTRU. Other phases of the lifecycle management of the AI / ML model (e.g., model generation, model monitoring, model updates) can also be completed at the WTRU, and / or at the base station and transmitted to the WTRU for deployment.

[0305] As described herein, the WTRU receives from the base station and uses to determine parameters of candidate beams. The WTRU can receive one or more of the following parameters from the base station (e.g., semi-statically via RRC signaling, or dynamically via MAC-CE or DCI, or via other logically equivalent messages or signaling or via other means) to perform or one or more associated beam predictions of the beams.

[0306] The WTRU can receive information indicating a time value and / or period (T BP ) to be used to perform (one or more) beam quality measurements of candidate beams (i.e., RI / PMI / CQI / L1-RSRP / SINR / RSRQ or other metrics). In some examples, the WTRU can receive a timer value, and when the timer value expires, it can trigger the assumption that any beam quality measurements performed by the WTRU on candidate beams may no longer be valid, thereby prompting / triggering the WTRU to repeat the measurements. In some examples, the WTRU can be configured with different periods for measuring different channel quality parameters. For example, L1-RSRP may need to be measured at a higher period than CQI. In some examples, the WTRU can implicitly determine T BP based on knowledge of T d .

[0307] The WTRU can receive information indicating a time duration (T d ) for which a prediction of (one or more) selected beam qualities (PMI, CQI, RI, L1-RSRP, SINR, RSRQ) needs to be valid, such that the corresponding beam set / subset is considered eligible for the set. In some examples, the WTRU can receive information indicating one or more time durations for which the measured selected beam quality metrics are considered valid. In some examples, the valid duration of one metric may be different from another (i.e., the CQI valid duration may be longer than the L1-RSRP). In some examples, the WTRU can implicitly determine T BP based on knowledge of T d。

[0308] The WTRU may receive one or more target thresholds of channel quality parameters (e.g., PMI, CQI, RI, minimum L1-RSRP, minimum SINR, minimum RSRQ) for one or more candidate beams. In some examples, the WTRU may be pre-configured with the target thresholds such that the L1-RSRP of the beams in the candidate beam set may need to exceed the target threshold to be considered compliant with the set. In some examples, the target thresholds may vary according to environmental / propagation characteristics. For example, in a dense urban environment, the WTRU may receive a threshold for CQI from the base station, which may be different from the CQI threshold in a rural environment.

[0309] The WTRU may receive information indicating the number of beams in a candidate beam set that are expected to meet one or more beam quality parameters in order to be considered compliant with the set. In some examples, only one beam in the candidate beam set may need to meet one or more beam quality parameters in order to be considered compliant with the set. The WTRU may use one beam for beam failure recovery. In some examples, most of the beams in the candidate beam set (e.g., >90%) may need to have channel quality / quantity measurements (e.g., L1-RSRP) above a pre-configured target threshold in order to be considered compliant with the set.

[0310] The WTRU may receive a minimum number of beam quality parameters that must be above a pre-configured target threshold in order to be considered compliant with the set. In some examples, for a candidate beam set, it may be required to meet only one beam quality parameter (e.g., L1-RSRP) in order to be considered compliant with the set. In some examples, for a candidate beam set, it may be required to meet more than one beam quality parameter (e.g., RSRQ in addition to RSRP) in order to be considered compliant with the set.

[0311] The WTRU may receive an indication of a beam resource set (ψ associated with a specific frequency range (e.g., FR2) 2Configuration information for performing beam measurements and for use with AI / ML models to predict a candidate beam set. Beam resources can include CSI-RS or SSB for downlink measurements and / or SRS or TCI state for uplink measurements. The WTRU can implicitly determine T based on the period of the base station that provides the beam resource set to the WTRU BP and / or T d .

[0312] Methods for determining candidate beams are described herein An AI / ML model can be used to determine a subset or set of beams using beam quality predictions within a future time duration T d which is consistent with one or more of the following solutions. To select one or more a subset of beams in a subset or set of beams, an AI / ML model can be used to predict one or more of the beam quality parameters (e.g., PMI, CQI, RI, L1-RSRP, SINR, RSQR) for each beam in the candidate set or The WTRU can calculate the number of beams in each that meet the (one or more) target beam quality parameters. In some examples, such as when the beam quality parameters may vary over time, the WTRU can select the minimum beam quality predicted in the T interval and report it to the base station. In some examples, the WTRU can select the d with the highest number of beams that meet one or more predicted beam quality parameters In some examples, the WTRU can select the with the required number of beams that meet the requirements configured for one or more beam quality parameters In some examples, the WTRU can indicate the selected to the base station. For example, this can be done via a MAC-CE indication as a bitmap, a PRACH transmission (each configured with a unique preamble), or via other methods generally described herein. Upon receiving the indication from the WTRU, the base station can update

[0313] An AI / ML model can be used to select a subset of beams from as follows. The AI / ML model can predict one or more of the beam quality parameters (PMI, CQI, RI, L1-RSRP, SINR, RSQR) for each beam in and the WTRU can use the beam quality parameters to determine a subset of candidate beams. The WTRU may indicate to the base station the selected candidate beams (where the beam quality parameter exceeds a threshold) (e.g., via a MAC-CE as a bitmap). Upon receiving the indication from the WTRU, the base station may update to include only the subset of beams indicated by the WTRU.

[0314] The WTRU may use to perform CFRA-BFR, whereby the WTRU may monitor beam resources when a beam failure is detected.

[0315] Methods for evaluating candidate beams are described herein. The WTRU may be configured to activate / deactivate AI / ML based on candidate beam prediction, and / or (re)evaluate a set / subset of candidate beams output by an AI / ML model based on one or more factors for effectiveness.

[0316] Factors for re-evaluating the effectiveness of a set / subset of candidate beams may include a time period. For example, the WTRU may be configured with periodic time instances (e.g., a default period) at which to check for effectiveness. The period may be increased from the default period in the event of possible changes in the channel conditions. In some examples, the WTRU may be triggered to check for effectiveness at a semi-persistent period, e.g., re-evaluate effectiveness every nth subframe unless triggered by an event (e.g., a change in channel measurements exceeding a threshold).

[0317] Factors for re-evaluating the effectiveness of a set / subset of candidate beams may include changes in the channel conditions. For example, a change in the channel conditions exceeding a threshold may indicate a trigger for the WTRU to re-evaluate for effectiveness. A change in the channel conditions may refer to a change detected in any one or more of RSRP, RSRQ, channel coherence time, channel coherence bandwidth, Doppler, Doppler spread, delay spread, LOS to NLOS, NLOS to LOS, or other measured values or parameters. For example, a change in L1 measurements (e.g., RSRP, RSRQ, CQI, PMI, RI, LI, SINR) exceeding a threshold may trigger the WTRU to re-evaluate for effectiveness.

[0318] Factors for re - evaluating the validity of a candidate beam set / sub - set can include receiving updated / new thresholds from the base station. For example, a WTRU can be configured to activate / de - activate AI / ML - based candidate beam prediction and / or (re)evaluate a candidate beam set / sub - set output by an AI / ML model based on the receipt of updated / new thresholds received from the base station and corresponding to any channel / beam quality measurements (e.g., RSRP, RSRQ, CQI, PMI, RI, LI, SNR, SINR, channel coherence time, channel coherence bandwidth, Doppler spread, etc.) of the validity.

[0319] Factors for re - evaluating the validity of a candidate beam set / sub - set can include the mobility of the WTRU. Changes in the base station / TRP, such as a change in the serving base station / TRP, can trigger the WTRU to re - evaluate of the validity. A change in positioning (e.g., translation, orientation) greater than a threshold can also trigger the WTRU to re - evaluate of the validity.

[0320] Factors for re - evaluating the validity of a candidate beam set / sub - set can include the location of the WTRU. Activating AI / ML - based candidate beam prediction at the WTRU can be location - based. In some solutions, the WTRU can receive an indication from the base station to activate the location - based evaluation. The WTRU can also receive information indicating a set of areas / regions (e.g., according to area index / region index) where the model may be valid and a threshold for location estimation accuracy.

[0321] Factors for re - evaluating the validity of a candidate beam set / sub - set can include RRC configuration or re - configuration, such as a change in RRC state (e.g., from inactive to connected state); a change in bandwidth part configuration; or a change in beams / beam pairs. For example, a change in the best - serving beam / beam pair can trigger the WTRU to re - evaluate a candidate beam set / sub - set of the validity.

[0322] Factors for re - evaluating the validity of a candidate beam set / sub - set can include the detection of beam failure / radio link failure.

[0323] The WTRU can be configured to activate / de - activate AI / ML - based candidate beam prediction and / or (re)evaluate a candidate beam set / sub - set output by an AI / ML model when the WTRU is triggered to transmit an SR / BSR, CG transmission, and / or UL RS (e.g., SRS) of the validity.

[0324] When the WTRU determines that the AI / ML model needs to be improved / retrained, the WTRU can be configured to activate or deactivate AI / ML-based candidate beam prediction and / or (re)evaluate the candidate beam set / subset output by the AI / ML model for effectiveness. In some examples, the WTRU can determine that the AI / ML model trained to determine the subset of active candidates in the beam set or is not performing well enough (e.g., the performance is not within the KPI thresholds sent by the base station to the WTRU).

[0325] The WTRU can be configured to activate / deactivate AI / ML-based candidate beam prediction and / or (re)evaluate the candidate beam set / subset output by the AI / ML model for effectiveness based on an updated / new AI / ML model received from the base station.

[0326] The WTRU can be configured to activate / deactivate AI / ML-based candidate beam prediction, and / or (re)evaluate the candidate beam set / subset output by the AI / ML model for effectiveness based on an explicit request received from the base station to re-evaluate AI / ML-based candidate beam selection.

[0327] The WTRU can be configured to activate / deactivate AI / ML-based candidate beam prediction, and / or (re)evaluate the candidate beam set / subset output by the AI / ML model for effectiveness based on additional beam resources / CSI-RS resources received from the base station.

[0328] The WTRU can be configured to activate / deactivate AI / ML-based candidate beam prediction, and / or (re)evaluate the candidate beam set / subset output by the AI / ML model for effectiveness based on the rotation of the WTRU.

[0329] Methods for AI / ML-assisted location / time-based set determination are described herein. In the examples described in the following paragraphs, parameters such as location, direction of motion, and speed estimation / reporting can be considered.

[0330] ​A WTRU may receive one or more pilot RSs (e.g., CSI-RS). In some solutions, the WTRU may perform measurements on the RSs (e.g., path loss, L1-RSRP, Doppler frequency, communication delay, LoS probability, etc.). Based on the measurements, the WTRU may estimate its location (e.g., relative location to a base station), direction of movement, and / or speed by using an AI / ML model. The WTRU may report its estimated location, direction of movement, and / or speed to the base station.

[0331] The WTRU may be configured to transmit one or more pilot RSs (e.g., one or more SRSs) to a base station. The base station may perform measurements and estimate the location (e.g., relative location), direction of movement, speed, and / or the correlation of its location information with other WTRUs of the WTRU.

[0332] Methods for candidate beam set configuration are described herein. In some solutions, the WTRU may be configured with a candidate beam set In some solutions, the WTRU may be configured with a set and such that

[0333] Figure 5 is and is a Venn diagram representation of. The candidate beam set may be partitioned / grouped into N subsets, where each subset represents a location area (R i , i ∈ {1, 2,..., N}) associated with the WTRU. The candidate beam set associated with the location area R i may be represented as As Figure 5 shown, the candidate beam set 500 is represented by and includes N partitioned subsets (i.e., and

[0334] In some solutions, the WTRU may be configured with a candidate beam set as well as a partitioned candidate beam set The WTRU may determine the candidate beam set as the union of all the partitioned sets, i.e., where U represents the union of the beam sets. The WTRU may determine by removing and all the mutual candidate beams of set, i.e.,

[0335] In some solutions, the WTRU may select one or more of the following as its current active candidate beam set Candidate beam set Location area candidate beam set (e.g., etc.); the union of two or more location area candidate beam sets (e.g., etc.); the union of all location area partition sets (the union); and / or set.

[0336] In some solutions, the WTRU may receive an indication of a set from the base station based on positioning information reported by the WTRU and / or estimated by the base station. The WTRU may be configured with a start symbol, time slot, or time and application time (e.g., start time applied after a time duration from a specific time instance) interval length for the indicated set. After the set is indicated to the WTRU, the start time and time interval length may be, for example, X symbols, time slots, or milliseconds (or another time unit). After the set is indicated to the WTRU, the start time and time interval length may be, for example, X symbols, time slots, or milliseconds (or another time unit).

[0337] In some solutions, the WTRU may be configured with or receive an indication of the association between the location / location of the WTRU and the candidate beam set which is basically illustrated in Figure 5 . The WTRU may determine its set based on its determined positioning information (i.e., location, speed, direction of movement) and the indicated association between its location and the candidate beam set . The WTRU may indicate its selection of by reporting its location information and / or one or more indices of (one or more) candidate beam subsets to the base station (e.g., via MAC-CE, PUCCH, or a preamble associated with each ). The WTRU may be configured with a start application time for the set. For example, X symbols / time slots / milliseconds after the WTRU reports its positioning information / new to the base station. The WTRU may be configured with the value of X by the base station via RRC signaling, MAC-CE, or DCI. The WTRU may determine the length of the application time of the set based on a positioning accuracy threshold (e.g., LoS probability). In some examples, the WTRU may be configured to select a candidate beam set application time t1 for a LoS probability p1 and an application time t2 for a LoS probability p2, where t1 > t2 and p1 > p2. The WTRU may determine based on its estimate of its current / future location The set may be applicable to a future time interval (e.g., X symbols / slots / milliseconds (or another time unit) in advance).

[0338] Figure 6 is a diagram illustrating an example of a CFRA - BFR process performed by a WTRU using location / time - based determination. As Figure 6 shown, the WTRU may move through location regions R1 to R at a given speed and in a given direction of movement N . As shown at 615, 625, 635, and 645, the WTRU may report information to the base station that is consistent with one or more of the above examples, which enables the base station to update the active candidate beam set based on the location of the WTRU (or the predicted location of the WTRU in a future time interval). For example, the WTRU may indicate its location within each region to the base station, and / or send an indication of the selected candidate beam set associated with the region in which the WTRU is located or the region it is predicted to be in the future . As shown at 610, 620, 630, and 640, the base station may update the active candidate beam set to use the beams associated with a particular location region

[0339] Default WTRU behavior and activation / de - activation procedures for AI / ML - assisted candidate beam determination are described herein. In some solutions, the WTRU may receive a dynamic indication (e.g., an indication based on MAC - CE and / or DCI, or other logical equivalents) to activate / de - activate location - based candidate beam set determination. When a fallback process is triggered, the WTRU may receive a de - activation indication. For example, such a situation may occur when the accuracy of location measurements (e.g., the LoS probability reported / determined by the base station) drops below a threshold. After receiving an activation indication, by default, the WTRU may be configured to select or a subset of (e.g., ) as its set. In addition to the activation indication, an initial set may also be indicated to the WTRU. In some solutions, the WTRU may determine the set after receiving activation of location - based candidate beam determination. The WTRU may use the "location - based BFR process" with the indicated / determined To perform BFR. The WTRU may also receive an indication of the activation time interval, for example, via a parameter such as positioning-bfr-time. When the amount of time elapsed since activation becomes equal to the activation time interval (e.g., as defined by positioning-bfr-time), the WTRU may disable location-based candidate beam determination.

[0340] The fallback process trigger is described herein. The WTRU may follow the "fallback process for location-based candidate beam determination" based on one or more triggers. The trigger may be based on the accuracy of the location estimate. When the accuracy of the location estimate drops below a predefined threshold, one such trigger may be satisfied. For example, if the LoS probability is less than the threshold p_fallback, the WTRU may switch to the fallback process. After reporting the LoS probability to the base station, the WTRU may follow the fallback process for selecting the candidate beam set for X symbols / slots / milliseconds. The WTRU may be configured with X by the base station via RRC signaling, MAC-CE, DCI, or other logically equivalent signaling.

[0341] When it is determined, based on beam quality measurements performed by the WTRU, that the quality (e.g., L1-RSRP) of all beams in the current active candidate beam set is below a threshold, the fallback process may be triggered.

[0342] When the measurement quality of the positioning-related signals (e.g., GNSS, PRS) drops below a predefined threshold, the fallback process may be triggered.

[0343] When the current position of the WTRU, as estimated by the WTRU, conflicts with the indicated set of the base station, the fallback process may be triggered. The WTRU may send an indication (e.g., a one-bit indication) to the base station to request a new set and / or a new association between the position and position area set of the WTRU

[0344] When the current position of the WTRU, as estimated by the base station, conflicts with the set determined by the WTRU the fallback process may be triggered. The WTRU may receive an indication (e.g., a one-bit indication) from the base station, followed by a new and / or an indication of a new association between the position and position area set of the WTRU

[0345] When the current position of the WTRU falls outside all position area sets or sets, the fallback process may be triggered. If such a situation is determined by the base station, the WTRU may, for example: receive an indication (e.g., a one-bit indication) from the base station, followed by a new​​ an indication of a new association between and / or a set of positions and location areas of the WTRU ; or receive a deactivation indication for location-based candidate beam determination.

[0346] If determined by the WTRU, the WTRU may send an indication (e.g., a one-bit indication) to the base station to request a new set and / or a set of positions and location areas of the WTRU new association between.

[0347] The WTRU may receive an explicit indication to follow a fallback procedure via an RRC / MAC-CE / DCI-based indication.

[0348] A fallback procedure for location-based candidate beam determination is described herein. In some solutions, the WTRU may expand its current active candidate beam set in one or more ways. The WTRU may include candidate beams from other location area sets into its set (e.g., if the fallback procedure is triggered due to a loss of location estimation accuracy). In some examples, the WTRU may include candidate beams from adjacent location area sets. For example, if the current then the WTRU may select a new

[0349] In some solutions, the WTRU may select as its set.

[0350] In some solutions, the WTRU may add one or more beams with QCL-Type D with PDCCH DMRS from the currently MAC-CE-indicated TCI state set.

[0351] In some solutions, the WTRU may receive an indication to switch to a default set based on a determination of an event more than a number of times pre-configured by the base station. This may occur when the CFRA-BFR attempt fails to find a new candidate beam for the set that results in CBRA-BFR. However, the new beam determined by CBRA-BFR (q new-CBRA-BFR ) may have the same spatial Tx / Rx parameters (QCL type-D) as the beams in the default set.

[0352] In some solutions, the WTRU may receive an indication or request to turn off or disable location-based candidate beam determination based on at least one of the following conditions. The condition may be that the accuracy of the location estimate remains below a threshold within a preconfigured time interval. For example, this may be when the LoS probability remains below a threshold p_switchoff within a preconfigured time interval position_bfr_los_max_time. If the number of times of CFRA-BFR determined using a location-based method exceeds a preconfigured threshold bfr_fail_max_count, the condition for disabling location-based candidate beam determination may be met. For example, this condition may be met if the number of CFRA-BFR failures exceeds the threshold within a time window defined by a parameter such as time_window_bfr_fail.

[0353] A location-based BFR process is described herein. The WTRU may use to perform BFR (e.g., CFRA-BFR) and use one or a combination of the following steps to determine BFR-related parameters. For example, the WTRU may monitor the beam quality (e.g., L1-RSRP) of candidate beam resources. When a beam failure or one or more beam failure instances are detected, the WTRU may initiate monitoring of candidate beams. Alternatively or additionally, the WTRU may periodically monitor candidate beams, where the period is configured by the base station. For example, where a is dynamically indicated via MAC-CE or DCI. The default value of a (e.g., a = 1) is RRC-configured. In some solutions, the WTRU may determine α based on location information. For example, the WTRU may determine α based on the LoS probability. For example, the WTRU may set α = α1 for LoS probability p1 and α = α2 for LoS probability p2, where α1 > α2 and p2 > p1.

[0354] The WTRU may select a beam with a measured beam quality (e.g., L1-RSRP) as a new candidate beam and indicate the selected beam to the base station. For example, the WTRU may select the beam corresponding to the highest measured L1-RSRP.

[0355] In some solutions, the WTRU may monitor candidate beams when at least one of the following conditions is met: when the direction of movement of the WTRU changes; when the LoS probability of the current beam drops below a threshold (e.g., configured by the base station); when the difference between the current position of the WTRU and the previously reported position exceeds a position / distance threshold; or when the speed of the WTRU exceeds a threshold.

[0356] The WTRU may indicate beam failure and its selection of a new beam by transmitting a preamble corresponding to the beam selected from . The WTRU may monitor the BFR-CORESET to obtain confirmation from the base station. In such a case, the WTRU may receive the confirmation from the base station using the new beam (e.g., by receiving a PDCCH transmission) and terminate the BFR procedure.

[0357] In the case where the WTRU does not receive confirmation of its beam selection within the monitoring window duration (which it may determine using the procedures substantially described herein), the WTRU may attempt to retransmit the preamble after increasing its transmission power. The WTRU may determine the increase in transmission power based on the BFR-related parameter determination procedures substantially described herein. In the case where the number of configured failed attempts reaches or exceeds a threshold and / or the WTRU cannot successfully recover using the BFR procedure before a timer expires (e.g., no new beam selection is made, or no confirmation is received from the base station, etc.), the WTRU may perform CBRA-BFR. For example, if the WTRU determines that no measurement of a beam in

[0358] satisfies the beam quality threshold (e.g., before the timer expires), the WTRU may perform CBRA-BFR. newMethod for set determination. The WTRU may initiate beam failure recovery based on a random access procedure. In some examples, the WTRU may be configured or configured with random access parameters, a start time duration set by the parameter BFR_Timer, and may apply a power ramp-up parameter. The WTRU may monitor and measure one or more of the reference signals based on resources specified by parameters such as candidateBeamRSList or candidateBeamRSSCellList. For example, the WTRU may determine whether at least one of the SSBs has an SS-RSRP higher than the corresponding RSRP_Threshold of the SSBs in the candidateBeamRSList or candidateBeamRSSCellList, or whether at least one of the CSI-RSs has a CSI-RSRP higher than the corresponding RSRP_Threshold of the CSI-RSs in the candidateBeamRSList or candidateBeamRSSCellList. Then, the WTRU may select the corresponding reference signal as a candidate new beam / random access resource for the BFR process. For example, the term q_new may be used to represent the newly selected beam / random access resource. The WTRU may use the corresponding random access resource and send a PRACH transmission according to the spatial relationship with the periodic CSI-RS resource configuration or with the SS / PBCH block associated with or QCL with the beam specified by the index q_new.

[0359] Alternatively or additionally, if uplink channel resources (e.g., uplink shared channel resources (UL-SCH)) are available, the WTRU may initiate a MAC-CE beam failure recovery process. Thus, the WTRU may generate a BFR MAC-CE and transmit it on the corresponding uplink channel resource.

[0360] The WTRU may determine, identify, or be configured with one or more CORESETs for use in a random access procedure that may be performed during beam failure recovery. In some examples, the WTRU may monitor PDCCH transmissions in a search space set to detect a DCI format (e.g., C-RNTI or MCS-C-RNTI) with a corresponding CRC scrambled with a radio network identifier. The WTRU may determine antenna port quasi-collocation parameters that are the same as those associated with the index q_new for monitoring the PDCCH in the search space set and receiving the corresponding PDSCH.

[0361] If the time duration specified by the parameter BFR_Timer has expired and if the beam failure recovery procedure has not been successfully completed, the WTRU may trigger link failure detection and then a link failure recovery (LFR) procedure.

[0362] The problem solved by one or more embodiments described herein may be whether or how to determine a set of (available) q_new for SCellBFR.

[0363] Some solutions may involve prediction of beam availability based on an AI / ML model. In some solutions, the WTRU may be configured or receive one or more thresholds for one or more measurement parameters (e.g., L1-RSRP), where the WTRU may use the thresholds to determine / predict beam availability (e.g., via an AI / ML model). Thresholds may be provided for one or more measurement parameters (e.g., rsrp-ThresholdBFR-AIML) or for the average of the measurement parameters over a time duration for a set of measurements (e.g., rsrp-ThresholdBFR-AIML-Avg). The WTRU may explicitly be provided with one or more thresholds (e.g., via RRC signaling or other logically equivalent signaling). Alternatively or additionally, the WTRU may implicitly determine one or more thresholds based on the provided differences / increments / offsets between the measurement parameters and / or measurement averages (e.g., between rsrp-ThresholdBFR-AIML / rsrp-ThresholdBFR-AIML-Avg and rsrp-ThresholdBFR).

[0364] In some solutions, the WTRU may determine / predict (e.g., using an AI / ML model) one or more measurement values or parameters (e.g., L1-RSRP) of one or more beams in a list (for beam failure recovery) at one or more time instances. The list may be provided by a parameter such as candidateBeamRSSCellList. For example, at time instance t0, the WTRU may determine / predict the L1-RSRP of one or more candidate beams at a future time instance t = T (e.g., T = a × the period of the beams in candidateBeamRSSCellList). In some embodiments, the WTRU may determine / predict (e.g., using an AI / ML model) the average value of one or more parameters (e.g., average L1-RSRP) of one or more beams in a list (e.g., a list of beams provided for beam failure recovery) over one or more time intervals. For example, at time t0, the WTRU may determine / predict the average L1-RSRP of one or more candidate beams (e.g., candidateBeamRSSCellList) over a future time interval (e.g., t1 ≤ t ≤ t2, where t0 ≤ t1 < t2).

[0365] In some solutions, the WTRU may determine / predict one or more newly selected beams (e.g., q_new). In cases where the WTRU is not configured to utilize an AI / ML model, the WTRU may use a conventional process to select q_new, which may be based on one or more measurement values or parameters (e.g., L1-RSRP). Alternatively, the WTRU may determine to enable the use of an AI / ML model for beam availability prediction (e.g., based on configuration information or a flag indication). In this way, the WTRU may determine / predict the newly selected beam based on a list of candidate beams (e.g., candidateBeamRSSCellList). When selecting / predicting q_new, one or more of the following determinations may be made. For example, the WTRU may determine that one or more measurement parameters of the selected / candidate beam are higher than a corresponding threshold (e.g., instantaneous L1-RSRP measurement value ≥ rsrp-ThresholdBFR). In some examples, the WTRU may determine that one or more predicted parameters (e.g., at time t = T) of the selected / candidate beam are higher than a corresponding threshold (e.g., rsrp-ThresholdBFR-AIML). In some examples, the WTRU may determine that one or more predicted average parameters (e.g., at time t = t0 over a future time interval) of the selected / candidate beam are higher than a corresponding threshold (e.g., rsrp-ThresholdBFR-AIMLAvg).

[0366] Methods for activating / deactivating the use of AI / ML models in beam availability prediction are described herein. In some solutions, a WTRU may determine whether to enable / disable (activate / deactivate) the use of an AI / ML model in beam availability prediction based on one or more implicit indications. In some examples, such as when the WTRU is configured / provided with one or more parameters (e.g., rsrp-ThresholdBFR-AIML and / or rsrp-ThresholdBFR-AIML-Avg), the WTRU may determine to activate / enable the AI / ML model.

[0367] In some solutions, the WTRU may be provided with an indication (e.g., a one-bit flag) for enabling / disabling (or activating / deactivating) the use of an AI / ML model in beam availability prediction. The WTRU may use the flag indication to determine whether to enable / disable the use of the AI / ML model. Alternatively or additionally, the WTRU may be configured to use the AI / ML model based on one or more of the following determinations. For example, the WTRU may determine that the MAC-CE transmission indicating the selected beam q_new may be subject to length / size constraints. In other words, after removing the beams predicted to be unavailable by the AI / ML, the remaining beams from which the WTRU may select q_new to initiate the MAC-CE beam failure recovery procedure may only allow a bitmap of limited size (e.g., an octet bitmap). In that case, the WTRU may decide to use the AI / ML model for beam availability prediction. The WTRU may indicate the use of the AI / ML model as part of a MAC-CE message.

[0368] In some examples, the WTRU may determine that there may be no remaining candidate beams from which to select q_new to initiate the MAC-CE beam failure recovery procedure after removing the beams predicted to be unavailable by the AI / ML from a list of candidate beams. In other words, the WTRU may determine that no beam in the list of candidate beams can meet both of the thresholds set by the parameters rsrp-ThresholdBFR and rsrp-ThresholdBFR-AIML. In this case, the WTRU may determine to use the AI / ML model for beam availability prediction.

[0369] The accuracy of the AI / ML model in beam availability prediction is described herein. In some solutions, the WTRU may determine the accuracy of the AI / ML model, where the WTRU may indicate / report the accuracy parameter to the base station and recommend / request / indicate the activation / deactivation of the AI / ML model. In some examples, the WTRU may be configured or provided with one or more parameters (e.g., a confidence level parameter) for determining the accuracy of the AI / ML model.

[0370] For example, a WTRU may be configured / provided with a parameter indicating a maximum allowable difference (e.g., delta_max_RSRP) between a predicted parameter (e.g., L1-RSRP within a future time instance t = T) and an actual measurement (e.g., at an actual future time instance t = T). In some examples, a WTRU may be configured / provided with a parameter indicating a maximum allowable difference (e.g., delta_max_RSRPAvg) between a predicted average value of a parameter (e.g., an average value of L1-RSRP within a future time instance t = T) and an actually measured average value (e.g., at an actual future time instance t = T).

[0371] The WTRU may determine whether a difference between a predicted parameter or an average value of a parameter and an actual value for one or more of the (selected) beams in a list of candidate beams exceeds a configured maximum allowable difference. In an example, the WTRU may calculate a difference between a measured L1-RSRP / average value of the measured L1-RSRP and a predicted L1-RSRP / average value of the predicted L1-RSRP for one or more of the candidate beams. The WTRU may determine whether the number of beams that fail to stay within a maximum difference threshold (e.g., delta_max_RSRP / delta_max_RSRPAvg) between the measured and predicted L1-RSRP / predicted average L1-RSRP exceeds a configured number. If the number of beams exceeds the configured number, the WTRU may perform one or more of the following steps. The WTRU may send an indication (e.g., to the base station) indicating that the accuracy of the AI / ML model for beam availability prediction is unacceptable (e.g., if the estimated accuracy has dropped below a threshold). The WTRU may indicate the AI / ML model accuracy using an indicator such as a one-bit flag, for example. In some cases, the WTRU may suggest / request / report to the base station to recalibrate or update the AI / ML model and / or convey further information about the AI / ML model to the WTRU.

[0372] AI / ML-assisted BFD-RS and configuration determination are described herein. In some solutions, the WTRU may recommend one or more BFD-RSs for BFR operation. For example, the WTRU may be semi-statically configured with a set of RSs for BFD (e.g., 64 beams). The WTRU may dynamically indicate the availability of each RS for BFD (e.g., a bitmap) or a set of RSs (e.g., a set index).

[0373] In some solutions, after receiving a base station confirmation (e.g., receiving one or more of PDCCH, DCI, and MAC-CE), the WTRU may monitor the recommended RS (or set of RSs) for BFD (BFD-RS set) (defined by both semi-static configuration and dynamic indication).

[0374] In some solutions, the WTRU may monitor the default BFD-RS before recommending the BFD-RS and / or receiving confirmation from the base station. For example, the WTRU may determine the top N or last N configured BFD-RS in the configured BFD-RS. In some examples, the WTRU may use the RS of QCL-Type D for PDCCH / CORESET / search space. The WTRU may monitor the recommended BFD-RS after recommending the BFD-RS and / or receiving confirmation from the base station.

[0375] In some solutions, in addition to the recommended BFD RS, the WTRU may also indicate other relevant information. For example, the WTRU may indicate the monitoring period and / or RS period of the BFD-RS.

[0376] The WTRU may indicate a detection quality threshold (e.g., for detecting beam failure instances). For example, the WTRU may indicate one or more qualities of beam failure detection (e.g., assumed PDCCH BLER and / or L1-RSRP).

[0377] The WTRU may indicate a detection counter threshold (e.g., for detecting beam failure instances). For example, the WTRU may indicate the number of beam failure detections (e.g., 3).

[0378] The WTRU may indicate a detection timer threshold. For example, the WTRU may indicate the value at which the timer for BFD expires.

[0379] The WTRU may indicate the time offset and / or duration of BFD-RS activation / deactivation. For example, the WTRU may indicate the time instance of BFD-RS activation / deactivation (e.g., 4 time slots from the WTRU indication) and / or the time duration (e.g., for activation during 30 time slots).

[0380] The indication of BFD-RS by the base station may be accompanied by various information. For example, the base station may dynamically indicate (e.g., via one or more of DCI, MAC-CE, or RRC) one or more BFD-RS with a monitoring period. For example, the base station may dynamically indicate the monitoring period of the BFD-RS. The WTRU may adaptively select the BFD-RS monitoring period based on the base station indication. If no signaling is received, the WTRU may monitor the BFD-RS based on the period of the BFD-RS. When indicated by the base station, the WTRU may monitor the BFD-RS with a period different from the period of the BFD-RS. For example, this may be a 1-bit indication to double the period when beam failures are less frequent (new period = 2x period of the BFD-RS).

[0381] The base station may indicate a detection quality threshold (e.g., for detecting beam failure instances). For example, the base station may indicate one or more qualities for beam failure detection (e.g., an assumed PDCCH BLER and / or L1-RSRP).

[0382] The base station may indicate a detection counter threshold (e.g., for detecting beam failure instances). For example, the WTRU may indicate a number for beam failure detection (e.g., 3).

[0383] The base station may indicate a detection timer threshold. For example, the WTRU may indicate a value at which the timer for BFD expires.

[0384] The base station may indicate a time offset and / or duration for BFD-RS activation / deactivation. For example, the WTRU may indicate a time instance for BFD-RS activation / deactivation (e.g., 4 time slots from when the WTRU indicates) and / or a time duration (e.g., for activation during 30 time slots).

[0385] Location-based BFD-RS and / or BFD parameter prediction is described herein. In some solutions, the WTRU may activate / deactivate BFD-RS and / or associated BFD parameters (e.g., monitoring period, detection quality threshold, detection counter threshold, detection timer threshold, and time offset and / or duration for BFD-RS activation / deactivation) based on one or more of the WTRU location, WTRU speed, direction of WTRU movement, and correlation of movement with other WTRUs in the vicinity of the WTRU.

[0386] For example, the WTRU may be configured with one or more IDs (e.g., area ID, direction ID, speed ID, etc.), and each ID may be associated with one or more BFD-RS and / or associated BFD parameters. The WTRU may activate or deactivate one or more BFD-RS and / or associated BFD parameters based on one or more parameters.

[0387] One such parameter may be the WTRU location. In some solutions, the WTRU may identify an ID associated with the WTRU location (e.g., area ID). Based on the identified ID, the WTRU may activate the BFD-RS and / or BFD parameters associated with the identified ID.

[0388] Another such parameter may be the WTRU direction. In some solutions, the WTRU may identify an ID associated with the direction of WTRU movement (e.g., direction ID). Based on the identified ID, the WTRU may activate the BFD-RS and / or BFD parameters associated with the identified ID.

[0389] Another such parameter can be the WTRU speed. In some solutions, the WTRU may identify an ID associated with the direction in which the WTRU is moving (e.g., a speed ID). For example, the WTRU may be configured with two thresholds (e.g., a first threshold and a second threshold (the first threshold < the second threshold)). If the WTRU speed is below the first threshold, the WTRU may determine a first ID. If the WTRU speed is above the first threshold and below (or equal to) the second threshold, the WTRU may determine a second threshold. If the WTRU speed is above the second threshold, the WTRU may determine a third threshold. Based on the identified ID, the WTRU may activate the BFD-RS and / or BFD parameters associated with the identified ID.

[0390] Described herein are embodiments that further describe the solutions presented in the above paragraphs. Some of the embodiments described herein relate to FR2 candidate beam set determination via FR1 beam quality measurements and an AI / ML model.

[0391] In some embodiments, the WTRU may receive an indication of a set ψ 1 (e.g., FR1 beams) and the association information between each candidate beam subset Alternatively or additionally, the WTRU may receive an indication of the association between each beam of ψ 1 and each candidate beam of The WTRU may receive the parameters for using an AI / ML model trained by a base station or another network node, or the WTRU may train an AI / ML model for candidate beam prediction. The WTRU may receive an indication from the base station / WTRU and determine to activate AI / ML-based blockage prediction and candidate beam set determination.

[0392] The WTRU may perform beam measurements (e.g., L1-RSRP) of ψ 1 and may use an AI / ML model to predict the blockage probability for each or each candidate beam (P blockage-1 , P blockage-2 ,..., P blockage-M ). The WTRU may indicate to the base station the indices of all or a selected set and / or the predicted blockage probabilities. The WTRU may receive new configuration information from the base station. For example, the WTRU may indicate: the indices and blockage probabilities of a preconfigured number of with the lowest / highest blockage probabilities; those with blockage probabilities lower / higher than a preconfigured threshold index; or a set that includes more than the configured number of candidate beams having a lower / higher blocking probability than the configured blocking probability threshold index.

[0393] The WTRU may update based on the blocking probability prediction of and indicate to the base station the selected set (e.g., via the MAC-CE / PUCCH / preamble for transmission associated with each ). The WTRU may indicate to the base station the set of all or selected individual candidate beams in

[0394] (i.e., ) and / or the predicted blocking probability. The WTRU may receive new configuration information from the base station. For example, the WTRU may indicate: the index and blocking probability of a pre-configured number of having the lowest / highest blocking probability, or the index of having a blocking probability below / above a pre-configured threshold. The WTRU may update based on the blocking probability prediction of each beam in (i.e., ) and indicate to the base station the selected set (e.g., via MAC-CE / PUCCH or other logically equivalent signaling). The WTRU may indicate to the base station the set of

[0395] and its associated blocking probability, or the WTRU selects a new which may be based on the result of the blocking prediction. For example, the WTRU may indicate a number of greater than the configured number in the current , where the current is predicted to have a blocking probability higher than the threshold blocking probability based on the new blocking prediction. Based on the AI / ML model prediction, the WTRU may determine that the number of in the current having a blocking probability higher than the pre-configured threshold exceeds the configured number.

[0396] The WTRU may monitor periodically or when a beam failure is detected and determine a new beam. The WTRU may perform BFR (e.g., CFRA-BFR) based on beam measurements and / or blocking probability prediction of the beams in . The WTRU may monitor periodically or when a beam failure / one or more beam failure instances are detected.The quality of the concentrated beam (e.g., L1-RSRP) for selecting a new beam. If at least one beam meets the required beam quality measurement value and / or the predicted blockage probability, the WTRU may select a new beam based on the beam measurement value (e.g., the beam with the highest L1-RSRP or the beam with an L1-RSRP exceeding a threshold) and the predicted blockage probability (e.g., the beam with the lowest blockage probability in or the beam with a blockage probability below a threshold). The WTRU may indicate beam failure and the selection of a new beam by transmitting a preamble corresponding to the new beam, and the WTRU may monitor the resources provided via the parameter BFR-CORESET to obtain confirmation from the base station. If no confirmation of selecting a new beam is received from the base station, the WTRU may repeat the preamble transmission process with increased transmission power. If

[0397] Figure 7 is a flowchart of steps for candidate beam set determination that can be performed by a WTRU, illustrated with the support of AI / ML beam prediction, based on configured beam quality measurement values and thresholds. As shown at 701, the WTRU measures a set of beams (ψ 1 ) to enable prediction of measurement values of beams outside the set of beams for which the measurement is being made (e.g., using a configured AI / ML model). At 702, the WTRU predicts (e.g., periodically based on the parameter T BP , or when a timer expires) the beam quality measurement values of the configured set of candidate beams . The types of beam quality measurements for candidate beam determination may include one or more of the following: PMI, CQI, RI, SINR, RSRQ, or L1-RSRP. It may be assumed that the beam prediction must be valid within a configured or determined duration (T d ). T BP and T d may be configured by the base station or determined by the WTRU (e.g., based on the period of ψ 1 ).

[0398] At 703, the WTRU receives configuration information indicating a beam quality measurement type and an associated threshold for determining a set of active candidate beams (e.g., via MAC-CE, RRC, or other logically equivalent signaling). At 704, the WTRU determines a set of active candidate beams based on the predicted beam quality and the configured measurement type / threshold. The threshold may be applied to individual configured candidate beams or a subset of the configured candidate beams. The WTRU also indicates the determined set of active candidate beams to the base station (e.g., via a MAC-CE in the form of a bitmap, via PRACH resource partitioning).

[0399] At 705, the WTRU monitors an indication of a set of configured monitored candidate beams from the base station. The WTRU may monitor at least one beam from the set of monitored candidate beams and determine a new candidate beam for beam failure recovery via CFRA-BFR. For example, upon detecting a beam failure, the WTRU may monitor at least one selected candidate beam; perform periodic monitoring based on a configured period; or upon network indication.

[0400] Some embodiments described herein may relate to location-based candidate set determination. For example, an AI / ML model implemented at a base station or another network node may assist in predicting a WTRU's possible future location and suitable candidate beam / beam set based on the WTRU's current location, the speed of the WTRU's movement, and the correlation of the movement with other nearby WTRUs.

[0401] The WTRU may be configured with a beam set A subset of candidate beams And May include all possible candidate beams. Candidate beam subset May include candidate beams associated with a location area R i . May include possible candidate beams not included in .

[0402] The WTRU may receive beam resources and configuration information for location estimation / prediction. The WTRU may report location estimation / measurements / predictions to the station. The WTRU may receive a set of candidate beams for BFR from the base station based on the reported positioning information

[0403] The WTRU may receive a set of candidate beams for BFR from the base station based on the positioning information estimated by the base station (e.g., indicating an index of a subset ).

[0404] The WTRU can receive a subset of candidate beams and an indication of the association between the location area (R i , i ∈ {1, 2,..., N}). The WTRU can determine its set based on its determined positioning information (i.e., location, velocity, direction of motion) and the indication association between its location and the subset of candidate beams . The WTRU can indicate its selection of by reporting its location information and / or the index(es) of the subset of candidate beams (e.g., via MAC-CE, PUCCH, or the preamble associated with each ) to the base station. The WTRU can start applying for BFR according to a start application time configured by the base station (e.g., X symbols / slots / milliseconds after the WTRU reports its positioning information / new to the base station). The WTRU can determine the length of the application time of the set based on a positioning estimation accuracy threshold (e.g., LoS probability).

[0405] The WTRU can receive a dynamic indication (e.g., an indication based on MAC-CE and / or DCI, or another logical equivalent) to activate / deactivate location-based candidate beam set determination. In some solutions, the WTRU can receive a dynamic indication (e.g., based on MAC-CE and / or DCI) to activate / deactivate location-based candidate beam set determination. After receiving the activation indication, the WTRU can select a configured default candidate beam set (e.g., or subset (e.g., ) as its set).

[0406] The WTRU can determine to follow a preconfigured fallback procedure for candidate beam selection under one or more of the following conditions. For example, when the accuracy of the position estimation may drop below a predefined threshold, if the LoS probability is less than the threshold (e.g., p_fallback), the WTRU can switch to the fallback procedure. If, based on the beam quality measurement values of the WTRU, the current active candidate beam set ​If the quality of all beams (e.g., L1-RSRP) in is determined to be below a threshold, the WTRU may determine to follow a pre-configured fallback procedure. If the measurement quality of positioning-related signals (e.g., GNSS, PRS) is below a predefined threshold, the WTRU may determine to follow a pre-configured fallback procedure. If the current position of the WTRU estimated by the base station conflicts with the set determined by the WTRU, the WTRU may determine to follow a pre-configured fallback procedure. If the current position of the WTRU is outside the boundaries of all location area sets or

[0407] set, the WTRU may determine to follow a pre-configured fallback procedure. If the WTRU receives an explicit indication to follow a fallback procedure via an RRC / MAC-CE / DCI-based indication, the WTRU may determine to follow a pre-configured fallback procedure. When the WTRU is instructed or determines to select a fallback procedure for candidate beam selection, the WTRU may use one or more of the following solutions to determine the WTRU may include candidate beams from other location area sets to its set (e.g., if the current then the WTRU may select a new ). The WTRU may select as its

[0408] The WTRU may use to perform BFR (e.g., CFRA-BFR). The WTRU may periodically or when detecting a beam failure / one or more beam failure instances monitor the quality of the beams (e.g., L1-RSRP) in to select a new beam. The candidate beam monitoring period may be configured by the base station or determined based on the accuracy of location information / location estimation (e.g., LoS probability). The WTRU may monitor candidate beams based on at least one of the following events: a change in the direction of movement of the WTRU; the LoS probability of the current beam drops below a configured threshold; or the speed of the WTRU is higher than a threshold. The WTRU may select a new beam based on beam measurement values (e.g., the beam with the highest L1-RSRP, or the beam with an L1-RSRP higher than a pre-configured threshold). The WTRU may indicate beam failure and the selection of a new beam by transmitting a preamble corresponding to the new beam, and the WTRU monitors the BFR-CORESET to obtain confirmation from the base station. If no confirmation of selecting a new beam is received from the base station, the WTRU may repeat the preamble transmission process with increased transmission power. If If no beam meets the required beam quality measurement or the WTRU fails to receive a new beam selection confirmation from the base station, the WTRU may perform CBRA-BFR.

[0409] Some embodiments described herein may relate to BFD-RS set determination. The WTRU may determine a BFD-RS set from a semi-statically configured RS set based on the availability determined by the WTRU For example, the WTRU may be semi-statically configured with a set of RSs for BFD (e.g., 64 beams). The WTRU may dynamically indicate the availability of each RS for BFD (e.g., using a bitmap) or a set of RSs (e.g., using a set index). After receiving a base station confirmation (e.g., receiving one or more of a PDCCH transmission, DCI, or MAC-CE), the WTRU may monitor the recommended RS (or set of RSs) for BFD (where the BFD-RS set is defined by both semi-static configuration and dynamic indication). Before the recommended BFD-RS is recommended and / or a confirmation is received from the base station, the WTRU may monitor the default BFD-RS. For example, the WTRU may determine the first / last N configured BFD-RSs in the configured BFD-RS. For example, the WTRU may use a QCL-Type D RS for PDCCH / CORESET / search space. The WTRU may monitor the recommended BFD-RS after the recommended BFD-RS is recommended and / or a confirmation is received from the base station.

[0410] In addition to the recommended BFD-RS, the WTRU may also indicate other BFD-related information (e.g., the WTRU may indicate one or more of the following): the monitoring period and / or RS period of the BFD-RS; the detection quality threshold (e.g., for detecting beam failure instances); the detection counter threshold (e.g., for detecting beam failure instances); the detection timer threshold (e.g., the value at which the WTRU may indicate that the timer for BFD has expired); or the time offset and / or duration of BFD-RS activation / deactivation.

[0411] The base station can dynamically indicate (e.g., via one or more of DCI, MAC-CE, RRC signaling, or another logically equivalent means) one or more BFD-RSs with various information. For example, the base station can dynamically indicate a monitoring period (e.g., the base station can dynamically indicate the monitoring period of the BFD-RS). The WTRU can adaptively select the BFD-RS monitoring period based on the base station indication. If no signaling is received, the WTRU can monitor the BFD-RS based on the period of the BFD-RS. When indicated by the base station, the WTRU can monitor the BFD-RS with a period different from the period of the BFD-RS. For example, the WTRU can receive a one-bit indication to double the period. The base station can dynamically indicate a detection quality threshold (e.g., for detecting beam failure instances). The base station can dynamically indicate a detection counter threshold (e.g., for detecting beam failure instances). In some cases, the base station can indicate the number of beam failure detections. The base station can dynamically indicate a detection timer threshold. For example, the WTRU can indicate the value at which the timer of the BFD expires. The base station can dynamically indicate the time offset and / or duration of BFD-RS activation / deactivation.

[0412] The WTRU can activate / deactivate the BFD-RS and / or associated BFD parameters (e.g., one or more of the monitoring period, detection quality threshold, detection counter threshold, detection timer threshold, and time offset and / or duration of BFD-RS activation / deactivation) based on one or more of the WTRU's location, speed, direction of movement, and correlation of movement with other nearby WTRUs of the WTRU. The WTRU can be configured with one or more IDs (e.g., area ID, direction ID, speed ID, etc.), and each ID can be associated with one or more BFD-RSs and / or associated BFD parameters. The WTRU can activate and deactivate one or more BFD-RSs and / or associated BFD parameters based on one or more of the WTRU's location, direction of movement, and speed.

[0413] Although the features and elements are described above in specific combinations, one of ordinary skill in the art will understand that each feature or element can be used alone or in combination with other features and elements. In addition, the methods described herein can be implemented in a computer program, software, or firmware that is incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as internal hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with the software can be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method for determining candidate beams for beam failure recovery performed by a wireless transmit / receive unit (WTRU), the method comprising: Receiving configuration information for receiving a set of first reference signals respectively associated with a set of first beams, configuration information for receiving a set of second reference signals respectively associated with a set of second beams, and one or more criteria for candidate beam selection; Receiving at least one of the set of first reference signals respectively associated with the set of first beams; And Transmitting information indicating a set of selected third beams that meet the received criteria for candidate beam selection, wherein the set of selected third beams is a set of proposed candidate beams to be monitored for beam failure recovery, and wherein the set of third beams is selected based on beam quality measurement values of at least one of the received set of first reference signals.

2. The method according to claim 1, wherein the set of third beams is selected based on predicted beam quality measurement values of the set of second reference signals, and the predicted beam quality measurement values of the set of second reference signals are based on beam quality measurement values of at least one of the received set of first reference signals.

3. The method according to claim 2, wherein the beams of the set of second beams do not overlap with any of the beams of the set of first beams.

4. The method according to claim 1, wherein the set of first reference signals is associated with a first frequency range, and wherein the set of second reference signals is associated with a second frequency range.

5. The method according to claim 1, further comprising: Receiving configuration information, the configuration information including an indication for monitoring a set of fourth reference signals respectively associated with a set of fourth beams for beam failure recovery; Monitoring at least one of the set of fourth reference signals; And transmitting a beam recovery request associated with at least one of the set of fourth beams.

6. The method according to claim 5, wherein the set of fourth beams is different from the set of selected third beams.

7. The method according to claim 5, wherein based on the received indication for monitoring the set of fourth beams, the WTRU determines that the set of fourth beams is the same as the set of selected third beams.

8. The method according to claim 1, wherein the criteria for candidate beam selection include at least one threshold associated with a beam quality measurement type.

9. The method according to claim 1, wherein the received configuration information includes an indication of one or more beam quality measurement types; and wherein the predicted beam quality measurement values of the set of second reference signals belong to the indicated one or more beam quality measurement types.

10. The method according to claim 1, including the WTRU periodically predicting beam quality measurement values of the set of second reference signals when an expiration period expires.

11. A wireless transmit / receive unit (WTRU) configured to determine candidate beams for beam failure recovery, the WTRU comprising: A processor; And A transceiver; The processor and transceiver are configured to receive configuration information for receiving a set of first reference signals respectively associated with a set of first beams, configuration information for receiving a set of second reference signals respectively associated with a set of second beams, and one or more criteria for candidate beam selection; The processor and transceiver are configured to receive at least one of the set of first reference signals respectively associated with the set of first beams; And The processor and transceiver are configured to transmit information indicating a set of third beams selected as satisfying the received criteria for candidate beam selection, wherein the set of selected third beams is a set of proposed candidate beams to be monitored for beam failure recovery, and wherein the set of third beams is selected based on beam quality measurement values of at least one of the received set of first reference signals.

12. The WTRU according to claim 11, wherein the set of third beams is selected based on predicted beam quality measurement values of the set of second reference signals, and the predicted beam quality measurement values of the set of second reference signals are based on beam quality measurement values of at least one of the received set of first reference signals.

13. The WTRU according to claim 11, wherein the beams of the set of second beams do not overlap with any of the beams of the set of first beams.

14. The WTRU according to claim 11, wherein the set of first reference signals is associated with a first frequency range, and wherein the set of second reference signals is associated with a second frequency range.

15. The WTRU according to claim 11, the processor and transceiver are further configured to: receive configuration information including an indication for monitoring a set of fourth reference signals respectively associated with a set of fourth beams for beam failure recovery; monitor at least one of the set of fourth reference signals; and transmit a beam recovery request associated with at least one of the set of fourth beams.

16. The WTRU according to claim 15, wherein the set of fourth beams is different from the set of selected third beams.

17. The WTRU according to claim 15, wherein based on the received indication for monitoring the set of fourth beams, the processor is configured to determine that the set of fourth beams is the same as the set of selected third beams.

18. The WTRU according to claim 11, wherein the criteria for candidate beam selection include at least one threshold associated with a beam quality measurement type.

19. The WTRU according to claim 11, wherein the received configuration information includes an indication of one or more beam quality measurement types; and wherein the predicted beam quality measurement values of the set of second reference signals belong to the indicated one or more beam quality measurement types.

20. The WTRU according to claim 11, the processor is configured to periodically predict beam quality measurement values of the set of second reference signals when the expiration date arrives.

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