Initial access for PRACH transmission

Abstract

A wireless transceiver unit (WTRU) may receive instructions for transmit synchronization signal blocks (SSBs) included in an SSB burst, as well as instructions for skipped SSBs within the SSB burst. Skipped SSBs are not transmitted by the base station in an SSB burst. The WTRU may decide to transmit instructions to use the skipped SSBs during or after the initial access procedure. The WTRU may transmit a random access preamble using random access resources and receive at least one downlink transmission using the beam associated with the skipped SSBs.

Description

Technical Field

[0001] This disclosure relates to initial access for PRACH transmission.

Background Art

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 457,029, filed Apr. 4, 2023, the entire contents of which are incorporated herein by reference.

[0003] NR, or New Radio, is a 5G mobile communication standard developed by the 3rd Generation Partnership Project (3GPP) to provide high-speed and reliable wireless communication services. NR includes various functions and technologies for improving communication quality, increasing network capacity, and reducing latency. Beam selection is one of the important functions of NR that helps improve the performance of wireless communication. Beam selection involves selecting the optimal beam direction or beamforming for transmitting and receiving wireless signals. By using beamforming, NR can concentrate the transmission energy in a specific direction, thereby improving signal quality, reducing interference, and increasing the range and capacity of the network.

Brief Description of the Drawings

[0004] [Figure 1A] A system diagram showing an exemplary communication system in which one or more of the disclosed embodiments may be implemented. [Figure 1B] A system diagram showing an exemplary wireless transmit / receive unit (WTRU) that may be used within the communication system shown in FIG. 1A according to one embodiment. [Figure 1C] A system diagram showing an exemplary radio access network (RAN) and an exemplary core network (CN) that may be used within the communication system shown in FIG. 1A according to one embodiment. [Figure 1D]This is a system diagram showing a radio access network (RAN) and a core network (CN) as further examples, which may be used in the communication system shown in Figure 1A according to one embodiment. [Figure 2] This figure shows an example of skipping transmission of a subset of SSB signals. [Modes for carrying out the invention]

[0005] A radio transceiver unit (WTRU) may receive instructions for one or more transmitted synchronization signal blocks (SSBs) and one or more skipped SSBs in an SSB burst. Each of the one or more skipped SSBs may not be transmitted by the base station in an SSB burst. The WTRU may decide to transmit an instruction to use a first of the one or more skipped SSBs. The WTRU may transmit a random access preamble using one or more random access resources. One or more random access preambles, or one or more random access resources, may indicate a first skipped SSB. The WTRU may receive at least one downlink transmission using the beam associated with the first skipped SSB.

[0006] The WTRU may also receive configuration information associated with one or more transmitted SSBs. This configuration information may include a list of candidate beams. The list of candidate beams may include beams associated with the first skipped SSB.

[0007] In one embodiment, configuration information may include a beam index, azimuth angle, elevation angle, or aiming angle. A random access preamble is transmitted using the beam associated with a first transmit SSB from a set of transmit SSBs, and one or more random access resources associated with the random access preamble or the first transmit SSB may indicate a first skipped SSB.

[0008] In one example, one or more random access resources may include a first random access resource and a second random access resource. The first random access resource may be associated with a first transmit SSB, and the second random access resource may be associated with a first skip SSB.

[0009] The WTRU may be further configured to receive a setting indicating whether SSB skipping is enabled.

[0010] WTRU may also be configured to use artificial intelligence (AI) / machine learning (ML) models to predict a preferred list of SSBs from a set of one or more skipped SSBs. One or more random access resources may be based on one or more transmitted SSBs, one or more skipped SSBs, or a combination of one or more transmitted SSBs and one or more skipped SSBs.

[0011] In one example, the first of one or more skipped SSBs may be used at the start of the initial access procedure or thereafter. Instructions sent in random access message 3 using one or more random access resources may indicate the first skipped SSB.

[0012] Figure 1A shows an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, and broadcast to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), quadrature FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero-tail intrinsic word DFT spread OFDM (ZT UW DTS-s OFDM), intrinsic word OFDM (UW-OFDM), resource block filtering OFDM, filter bank multicarrier (FBMC), and the like.

[0013] As shown in Figure 1A, the communication system 100 may include radio transceiver units (WTRUs) 102a, 102b, 102c, 102d, RAN (Radio Access Network) 104 / 113, CN (Core Network) 106 / 115, Public Switched Telephone Network (PSTN) 108, the Internet 110, and other networks 112. However, it will be understood that the disclosed embodiments assume any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, and 102d may be any type of device configured to operate and / or communicate in a radio environment. For example, WTRU 102a, 102b, 102c, and 102d (all sometimes referred to as “stations” and / or “STAs”) are configured to transmit and / or receive radio signals and may include user equipment (UEs), mobile stations, fixed or mobile subscriber units, subscriber-based units, pagers, mobile phones, PDAs (personal digital assistants), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, IoT (Internet of Things) devices, watches and other wearable devices, HMDs (head-mounted displays), vehicles, drones, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots and / or other wireless equipment operating in industrial and / or automated processing chain environments), consumer electronics, and equipment operating on commercial and / or industrial wireless networks. Any WTRU 102a, 102b, 102c, or 102d may be interchangeably referred to as a WTRU. Furthermore, any description made herein with reference to a UE may be equally applicable to a WTRU (and vice versa). For example, a WTRU may be configured to perform any of the processes or procedures described herein as being performed by a UE (and vice versa).

[0014] The communication system 100 may also include base stations 114a and / or base stations 114b. Each of the base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one WTRU (102a, 102b, 102c, 102d) and facilitate access to one or more communication networks such as the CN (106 / 115), the Internet (110), and / or other networks (112). For example, base stations 114a and 114b may be base transceiver stations (BTS), Node-B, eNode-B, Home Node-B, Home eNode-B, gNB, NR Node-B, site controller, access point (AP), wireless router, etc. Although base stations 114a and 114b are each illustrated as single elements, it will be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0015] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), and relay nodes. Base station 114a and / or base station 114b may be configured to transmit and receive radio signals on one or more carrier frequencies (which may be called cells (not shown)). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of radio services to a particular geographic area, which may be relatively fixed or change over time. A cell may be further divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, for example, one for each sector of the cell. In one embodiment, base station 114a may employ multiple input multiple output (MIMO) technology and utilize multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and / or receive signals in a desired spatial direction.

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

[0017] More specifically, as described above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA. For example, base stations 114a and WTRUs 102a, 102b, and 102c within RAN 104 / 113 may implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) and may establish airborne interfaces 115 / 116 / 117 using broadband CDMA (WCDMA). WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Advanced HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0018] In one embodiment, base stations 114a and WTRUs 102a, 102b, and 102c may implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA) and may establish an airborne interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0019] In one embodiment, the base station 114a and WTRUs 102a, 102b, and 102c may implement radio technologies such as NR radio access and establish an airborne interface 116 using New Radio (NR).

[0020] In one embodiment, base stations 114a and WTRUs 102a, 102b, and 102c may implement multiple radio access technologies. For example, base stations 114a and WTRUs 102a, 102b, and 102c may implement both LTE and NR radio access, for example, using the dual connectivity (DC) principle. Thus, the airborne interfaces used by WTRUs 102a, 102b, and 102c may be characterized by multiple types of radio access technologies and / or multiple types of transmissions transmitted to and from multiple types of base stations (e.g., eNBs and gNBs).

[0021] In other embodiments, base stations 114a and WTRUs 102a, 102b, and 102c may employ 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, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0022] The base station 114b shown in Figure 1A is, for example, a wireless router, Home Node-B, Home eNode-B, or access point, and can utilize any suitable radio access technology (RAT) to facilitate wireless connectivity in local areas such as offices, homes, vehicles, campuses, industrial facilities, airspace (e.g., for drones), and roads. In one embodiment, the base station 114b and WTRU 102c, 102d may implement radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and WTRU 102c, 102d may implement radio technology (e.g., IEEE 802.15) to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and WTRU 102c, 102d may utilize cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. As shown in Figure 1A, base station 114b may be directly connected to the internet 110. Thus, base station 114b may not need to access the internet 110 via CN106 / 115.

[0023] RAN104 / 113 may communicate with CN106 / 115, which may be any type of network configured to provide voice, data, applications, and / or voice over Internet Protocol (VoIP) services to one or more of WTRU102a, 102b, 102c, and 102d. The data may have various quality of service (QoS) requirements, including different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, and mobility requirements. CN106 / 115 may provide call control, billing services, mobile location services, prepaid calls, internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although not shown in Figure 1A, it is understood that RAN104 / 113 and / or CN106 / 115 may communicate directly or indirectly with other RANs employing the same or different radio access technologies (RATs) as RAN104 / 113. For example, in addition to being connected to RAN104 / 113 which utilizes NR radio technology, CN106 / 115 may also communicate with another RAN (not shown) employing GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0024] CN106 / 115 can also function as a gateway for the WTRU102a, 102b, 102c, 102d to access the PSTN108, the Internet 110, and / or other networks 112. The PSTN108 can include a circuit-switched telephone network that provides a traditional 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 this CN can employ the same radio access technology (RAT) as the RAN104 / 113 or a different RAT.

[0025] Some or all of the WTRU102a, 102b, 102c, 102d within the communication system 100 can include multimode functionality (e.g., the WTRU102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks via different wireless links). For example, the WTRU102c shown in FIG. 1A can be configured to communicate with a base station 114a that can employ a cellular-based radio technology and a base station 114b that can employ IEEE 802 radio technology, respectively.

[0026] Figure 1B is a system diagram showing an exemplary WTRU 102. As shown in Figure 1B, the WTRU 102 may include a processor 118, a transceiver 120, a transceiver 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 may include any sub-combination of the foregoing elements while maintaining consistency with the embodiments.

[0027] The processor 118 may be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors cooperating with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal encoding, data processing, power control, input / output processing, and / or other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 may be connected to the transceiver 120, and the transceiver 120 may be connected to the transceiver element 122. Although Figure 1B shows the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated within an electronic package or chip.

[0028] The transmitting / receiving element 122 may be configured to transmit signals to a base station (e.g., base station 114a) via the radio interface 116, or to receive signals from a base station. For example, in one embodiment, the transmitting / receiving element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmitting / receiving element 122 may be a light-emitting / photodetector configured to transmit and / or receive, for example, infrared, ultraviolet, or visible light signals. In yet another embodiment, the transmitting / receiving element 122 may be configured to transmit and / or receive both RF signals and optical signals. It will be understood that the transmitting / receiving element 122 may be configured to transmit and / or receive any combination of radio signals.

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

[0030] The transceiver 120 may be configured to modulate the signal transmitted by the transmitting / receiving element 122 and demodulate the signal received by the transmitting / receiving element 122. As described above, the WTRU 102 may have multimode functionality. Therefore, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR or IEEE 802.11.

[0031] The processor 118 of the WTRU102 is connected to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit) and may receive user input data from them. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Furthermore, the processor 118 may access information and store data from any suitable memory, such as non-removable memory 130 and / or removable memory 132. 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. Removable memory 132 may include a subscriber identification module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from memory not physically located on the WTRU 102, such as a server or a home computer (not shown), and store data.

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

[0033] The processor 118 may also be connected to a GPS chipset 136 which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via the radio interface 116, and / or determine its location based on the timing of signals received from two or more neighboring base stations. It will be understood that the WTRU 102 may acquire location information by any suitable localization method while remaining consistent with this embodiment.

[0034] The processor 118 may be further connected to other peripherals 138, which may include one or more software and / or hardware modules that provide additional functions, performance, and / or wired or wireless connectivity. For example, peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a Universal Serial Bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency 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. Peripherals 138 may include one or more sensors, which may include one or more gyroscopes, accelerometers, Hall effect sensors, magnetometers, compass sensors, proximity sensors, temperature sensors, time sensors, position sensors, altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and / or humidity sensors.

[0035] WTRU102 may include a full-duplex radio in which some or all of all signals (e.g., those associated with specific subframes in both UL (uplink, for transmission) and DL (downlink, for reception)) are transmitted and / or received in parallel and / or simultaneously. This full-duplex radio includes an interference management unit 139 which can reduce and / or substantially eliminate self-interference through signal processing by hardware (e.g., chokes) or a processor (e.g., a separate processing unit (not shown) or processor 118). In one embodiment, WTRU102 may include a radio in which some or all of the signals (e.g., signals associated with specific subframes in either UL (for transmission) or downlink (for reception)) are transmitted and received in half-duplex.

[0036] Figure 1C is a system diagram showing RAN104 and CN106 according to one embodiment. As described above, RAN104 may employ E-UTRA radio technology to communicate with WTRU102a, 102b, and 102c via the radio interface 116. RAN104 may also be able to communicate with CN106.

[0037] The Radio Access Network (RAN) 104 may include eNode-B160a, 160b, and 160c, but it will be understood that RAN 104 may include any number of eNode-B while maintaining consistency with the embodiment. Each of the eNode-B160a, 160b, and 160c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c via the radio interface 116. In one embodiment, the eNode-B160a, 160b, and 160c may implement MIMO technology. Thus, for example, the eNode-B160a may use multiple antennas to transmit radio signals to and / or receive radio signals from the WTRU102a.

[0038] Each of the eNode-B160a, 160b, and 160c may be associated with a specific cell (not shown) and configured to handle decisions regarding radio resource management, handover decisions, user scheduling in UL and / or DL, etc. As shown in Figure 1c, the eNode-B160a, 160b, and 160c may communicate with each other via the X2 interface.

[0039] The CN106 shown in Figure 1C may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (or PGW) 166. While each of these elements is shown as part of CN106, it should be noted that these elements may be owned and / or operated by entities other than the CN operator.

[0040] The MME162 can be connected to each eNode-B162a, 162b, and 162c within RAN104 via the S1 interface and function as a control node. For example, the MME162 may be responsible for user authentication of WTRU102a, 102b, and 102c, enabling / disabling bearers, and selecting a specific serving gateway during the initial attachment of WTRU102a, 102b, and 102c. The MME162 may also provide control plane functionality for switching between RAN104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0041] The SGW164 can be connected to each eNode-B160a, 160b, and 160c in RAN104 via the S1 interface. The SGW164 can typically route and forward user data packets to and from WTRU102a, 102b, and 102c. The SGW164 can also perform other functions, such as anchoring the user plane during eNode-B handovers, triggering paging when DL data is available for WTRU102a, 102b, and 102c, and managing and storing the context of WTRU102a, 102b, and 102c.

[0042] SGW164 can be connected to PGW166, which provides WTRU102a, 102b, and 102c with access to packet-switched networks such as the Internet 110, facilitating communication between WTRU102a, 102b, and 102c and IP-enabled devices.

[0043] CN106 may enable communication with other networks. For example, CN106 may provide WTRU102a, 102b, and 102c with access to circuit-switched networks such as PSTN108, and enable communication between WTRU102a, 102b, and 102c and conventional fixed communication equipment. For example, CN106 may include, or communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN106 and PSTN108. Furthermore, CN106 may provide WTRU102a, 102b, and 102c with access to other networks 112, including other wired and / or wireless networks owned and / or operated by other service providers.

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

[0045] In a typical embodiment, the other network 112 may be a WALN (Wireless LAN).

[0046] A wireless LAN (WLAN) in Infrastructure Basic Service Set (BSS) mode may have access points (APs) for the BSS and one or more stations (STAs) associated with those APs. The APs may have access to or interfaces with a distributed system (DS) or other type of wired / wireless network responsible for sending and receiving traffic to and from the BSS. Traffic originating from outside the BSS destined for an STA may arrive via the AP and be delivered to the STA. Traffic originating from an STA destined for outside the BSS may be sent to the AP and delivered to its respective destination. Inter-STA traffic within the BSS may be transmitted via the AP, for example, by a source STA sending traffic to the AP, which then delivers the traffic to the destination STA. Inter-STA traffic within the BSS may be considered, or referred to as, peer-to-peer traffic. Peer-to-peer traffic may be transmitted between a source STA and a destination STA (e.g., directly) using a Direct Link Setup (DLS). In typical embodiments, the DLS may be an 802.11e DLS or an 802.11z Tunneled DLS (TDLS). A WLAN using Independent BSS (IBSS) mode may not have access points (APs), and STAs (e.g., all STAs) within or utilizing IBSS communicate directly with each other. In this specification, the IBSS communication mode may be referred to as the "ad-hoc" communication mode.

[0047] When using the 802.11ac infrastructure operating mode or a similar operating mode, an AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be of a fixed width (e.g., 20 MHz bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel for the BSS, and the STA may be used to establish a connection with the AP. In a typical embodiment, for example in an 802.11 system, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented. In CSMA / CA, the STA, including the AP (e.g., all STAs), may sense the primary channel. If a particular STA senses / detects the primary channel and / or determines it to be busy, the STA may backoff. In a particular BSS, one STA may transmit at any given time.

[0048] High-throughput (HT) STAs can use a 40MHz wide channel for communication, for example, by combining a primary 20MHz channel with adjacent or non-adjacent 20MHz channels to form a 40MHz wide channel.

[0049] Ultra-high-throughput (VHT) STAs may support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz, with 40 MHz and / or 80 MHz channels being formed by combining consecutive 20 MHz channels. A 160 MHz channel may be formed by combining eight consecutive 20 MHz channels or two discontinuous 80 MHz channels, the latter sometimes referred to as an 80+80 configuration. In an 80+80 configuration, the data after channel coding may pass through a segment parser that splits the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing may be performed separately for each stream. The streams are mapped to two 80 MHz channels, and the data is transmitted by the transmitting STA. In the receiver of the receiving STA, the processing of the 80+80 configuration described above may be performed in reverse order, and the combined data may be transmitted to Media Access Control (MAC).

[0050] 802.11af and 802.11ah support operating modes below 1 GHz. 802.11af and 802.11ah reduce the channel operating bandwidth and carrier compared to those used in 802.11n and 802.11ac. 802.11af supports bandwidths of 5 MHz, 10 MHz, and 20 MHz in the TV white space (TVWS) spectrum, while 802.11ah supports bandwidths of 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz using the non-TVWS spectrum. According to a typical embodiment, 802.11ah may support meter-type control / machine-type communications (MTC), such as MTC devices within a macro coverage area. MTC devices may have specific capabilities, including limited functionality with support for specific bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life exceeding a threshold (e.g., to maintain a very long battery life).

[0051] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include a channel that can be designed as the primary channel. The primary channel may have a bandwidth equivalent to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by the STA that supports the minimum bandwidth operating mode from among all STAs in the operating BSS. In the 802.11ah example, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, or other channel bandwidth operating modes, the primary channel may be 1MHz wide for an STA that supports 1MHz mode (e.g., an MTC type device). Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. For example, if the primary channel is occupied because an STA supporting 1MHz operating mode is transmitting to an AP, the entire potentially available frequency band may be considered occupied, even if most of the frequency band is unused and available.

[0052] In the United States, the usable frequency band for 802.11ah is from 902 MHz to 928 MHz. In South Korea, the usable frequency band is from 917.5 MHz to 923.5 MHz. In Japan, the usable frequency band is from 916.5 MHz to 927.5 MHz. The total usable bandwidth for 802.11ah is from 6 MHz to 26 MHz, depending on the country code.

[0053] Figure 1D is a system diagram showing RAN113 and CN115 according to one embodiment. As described above, RAN113 may employ NR radio technology to communicate with WTRU102a, 102b, and 102c via AiRIF116. RAN113 may communicate with CN115.

[0054] The Radio Access Network (RAN) 113 may include gateway network branches (gNBs) 180a, 180b, and 180c, but it will be understood that the RAN 113 may include any number of gNBs, provided that this is consistent with the embodiment. Each of the gNBs 180a, 180b, and 180c may include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via the radio interface 116. In one embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNBs 180a and 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, and 180c. Thus, for example, the gNB 180a may use multiple antennas to transmit radio signals to and / or receive radio signals from the WTRU 102a. In one embodiment, gNB180a, 180b, and 180c may implement carrier aggregation techniques. For example, gNB180a may transmit multiple constituent carriers to WTRU102a (not shown). Some of these constituent carriers may be on the unlicensed spectrum, and the remaining constituent carriers may be on the licensed spectrum. In one embodiment, gNB180a, 180b, and 180c may implement cooperative multipoint (CoMP) techniques. For example, WTRU102a may receive cooperative transmissions from gNB180a and gNB180b (and / or gNB180c).

[0055] WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using transmissions associated with scalable numerical systems. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different parts of the radio transmission spectrum. WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using subframes or transmission time intervals (TTI) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or having different absolute time lengths).

[0056] The gNB180a, 180b, and 180c can be configured to communicate with WTRU102a, 102b, and 102c in standalone and / or non-standalone configurations. In a standalone configuration, the WTRU102a, 102b, and 102c can communicate with the gNB180a, 180b, and 180c without accessing other radio access networks (e.g., eNode-B160a, 160b, and 160c). In a standalone configuration, the WTRU102a, 102b, and 102c can utilize one or more gNB180a, 180b, and 180c as mobility anchor points. In a standalone configuration, the WTRU102a, 102b, and 102c can communicate with the gNB180a, 180b, and 180c using unlicensed band signals. In a non-standalone configuration, WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c while communicating with other RANs such as eNode-B160a, 160b, and 160c. For example, WTRU102a, 102b, and 102c can implement DC principles to communicate substantially simultaneously with one or more gNB180a, 180b, and 180c and one or more eNode-B160a, 160b, and 160c. In a non-standalone configuration, eNode-B160a, 160b, and 160c can act as mobility anchors for WTRU102a, 102b, and 102c, and gNB180a, 180b, and 180c can provide additional coverage and / or throughput in servicing WTRU102a, 102b, and 102c.

[0057] Each of the gNB180a, 180b, and 180c may be associated with a specific cell (not shown) and configured to perform radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, dual connectivity, interconnection between NR and E-UTRA, routing to user plane data (UPF) 184a, 184b, routing to control plane information (AMF) 182a, 182b, and similar operations. As shown in Figure 1D, the gNB180a, 180b, and 180c may communicate with each other via the Xn interface.

[0058] The CN115 shown in Figure 1D may include at least one AMF182a, 182b, at least one UPF184a, 184b, at least one Session Management Function (SMF)183a, 183b, and possibly a Data Network (DN)185a, 185b. While each of the above elements is shown as part of the CN115, it should be noted that any of these elements may be owned and / or operated by entities other than the CN operator.

[0059] AMF182a and 182b can be connected to one or more gNB180a, 180b, and 180c within RAN113 via the N2 interface and function as control nodes. For example, AMF182a and 182b may be responsible for user authentication of WTRU102a, 102b, and 102c, support for network slicing (e.g., handling different PDU sessions with different requirements), selection of specific SMF183a and 183b, management of registration areas, termination of NAS signaling, and mobility management. Network slicing may be used by AMF182a and 182b to customize CN support for WTRU102a, 102b, and 102c based on the types of services utilized by WTRU102a, 102b, and 102c. For example, different network slices may be established for different use cases, such as services that rely on ultra-reliable low-latency communications (URLLC) access, services that rely on enhanced large-scale mobile broadband (eMBB) access, services for machine-type communications (MTC) access, and / or similar services. The AMF162 may provide control plane functionality for switching between RAN113 and other RANs (not shown) employing other radio technologies such as LTE, LTE-A, LTE-A Pro, and non-3GPP access technologies such as WiFi.

[0060] SMF183a and 183b may be connected to AMF182a and 182b in CN115 via the N11 interface. SMF183a and 183b may also be connected to UPF184a and 184b in CN115 via the N4 interface. SMF183a and 183b may select and control UPF184a and 184b and configure routing for traffic passing through them. SMF183a and 183b may perform other functions, such as managing and assigning WTRU IP addresses, managing PDU sessions, enforcing policies and controlling QoS, and providing downlink data notifications. PDU session types may be IP-based, non-IP-based, Ethernet-based, etc.

[0061] UPF184a, 184b may be connected to one or more gNB180a, 180b, 180c in RAN113 via the N3 interface and may provide WTRU102a, 102b, 102c with access to a packet-switched network such as the Internet 110 to facilitate communication between WTRU102a, 102b, 102c and IP-enabled devices. UPF184a, 184b may also perform other functions such as packet routing and forwarding, enforcement of user plane policies, support for multi-homed PDU sessions, handling of user plane QoS, buffering of downlink packets, and providing mobility anchoring.

[0062] CN115 can facilitate communication with other networks. For example, CN115 may include, or communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that functions as an interface between CN115 and PSTN108. Furthermore, CN115 may provide WTRU102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRU102a, 102b, 102c are connected to local data networks (DNs) 185a, 185b via an N3 interface to UPF184a, 184b and an N6 interface between UPF184a, 184b and DN185a, 185b.

[0063] Referring to Figures 1A-1D and the corresponding descriptions, one or more, or all, of the functions described herein relating to one or more of the other devices described herein, such as WTRU102a-d, base stations 114a-b, eNode-B160a-c, MME162, SGW164, PGW166, gNB180a-c, AMF182a-ab, UPF184a-b, SMF183a-b, DN185a-b, and / or other devices described herein, may be performed by one or more emulation devices (not shown). An emulation device may be one or more devices configured to emulate some or all of the functions described herein. For example, an emulation device may be used to test other devices and / or to simulate network and / or WTRU functions.

[0064] Emulation devices may be designed to implement one or more tests against other devices in experimental and / or carrier network environments. For example, one or more emulation devices may perform one or more functions, or all of them, to test other devices in a communications network while fully or partially implemented and / or deployed as part of a wired and / or wireless communications network. One or more emulation devices may perform one or more functions, or all of them, while temporarily implemented / deployed as part of a wired and / or wireless communications network. Emulation devices may be directly connected to other devices for testing purposes and / or may perform tests using wireless airborne communications.

[0065] One or more emulation devices may perform one or more functions (including all functions) when not implemented / deployed as part of a wired and / or wireless communication network. For example, an emulation device may be used to implement testing of one or more components in a test scenario in a test lab and / or in a non-deployed state (e.g., for testing) of a wired and / or wireless communication network. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation device to send and receive data.

[0066] Beam management can be implemented as one of the target use cases for AI / ML for aerial interfaces. This technology can improve the performance and / or complexity of conventional beam management, including beam prediction in the time and spatial domains, with the aim of reducing overhead and latency and improving beam selection accuracy.

[0067] In conventional NRs, the gNB can select a set of SS / PBCH blocks (SSBs) to be transmitted in an SSB burst, and the list of SSBs transmitted within the SSB burst may be shown via ssb-PositionsInBurst in SIB1. The transmission of an SSB beam (e.g., up to 64) can impose a relatively large payload and / or overhead on the gNB's performance. Reducing the number of transmitted SSBs can impact system performance and latency. Thus, the gNB may skip the transmission of some SSBs and transmit a subset of them, and the WTRU can predict the optimal beam based on the transmitted SSBs (e.g., using an AIML system). An example of such a scenario is shown in Figure 2, where the gNB transmits a subset of the beam (shown by a solid line) and skips the transmission of another subset (shown by a dashed line). This results in different behavior of the WTRU in SSB beam prediction and subsequent initial access procedures. The WTRU may need to determine inputs, conditions, measurements, etc., for inference and validation purposes. Accordingly, embodiments relating to SSB skipping and enhanced NR AI / ML beam management are described herein.

[0068] A WTRU can efficiently perform initial access in a system with skipped SSBs. Embodiments of initial access in an AIML scenario with skipped SSBs are described herein. As an example, a WTRU may consist of a set of transmitted SSB beams and a set of predicted SSB beams. The WTRU may select the predicted beams to perform initial access on (e.g., based on predicted RSRP). The WTRU may initiate initial access by transmitting a PRACH preamble on a PRACH resource, which may be selected based on one or more of the relevant detected SSB beams, predicted SSB beams, and / or combinations of multiple detected and / or predicted SSB beams. To perform initial access in an AIML system with skipped SSBs, an SSB beam prediction procedure in the skipped SSB system (e.g., the use of Set A and Set B in the skipped SSB system, described later) may be performed. In an AIML scenario with skipped SSBs, a PRACH preamble transmission may be performed.

[0069] In one embodiment, the WTRU may initiate initial access by transmitting a PRACH preamble on a PRACH resource, which may be selected based on the relevant detected SSB beam or the SSB actually transmitted. For example, the WTRU may be configured to transmit a PRACH preamble on the resource corresponding to the relevant detected SSB beam. The WTRU may indicate to the gNB a preferred predicted beam as a result of the selection of the PRACH preamble or the transmission of Msg3, or in a transmission performed after the RA procedure. For example, in RAR, the gNB may indicate whether the predicted beam is acceptable (by transmitting the same RAPID(preamble ID) or by transmitting a different ID to instruct the WTRU to select a different beam (a detected beam or a predicted beam)). For example, this may apply in situations where the gNB did not transmit an SSB due to the gNB's implementation (e.g., the gNB turns off those beams to reduce power consumption). For example, the gNB may not want to receive anything on those beams. The gNB may not use those beams unless requested by the WTRU.

[0070] A WTRU may initiate initial access by transmitting a PRACH preamble on a PRACH resource, which may be selected based on predicted or skipped SSB beams. For example, a WTRU may be configured to transmit a PRACH preamble on a resource corresponding to one of the predicted SSB beams (e.g., the one with the highest RSRP). A WTRU may be configured or determined to use one or more random access parameters (e.g., for PRACH transmission and RAR reception, e.g., the number of PRACH preamble retransmissions, power ramp-up value, etc.).

[0071] A WTRU may initiate initial access by transmitting a PRACH preamble on a PRACH resource, which may be selected based on a combination of detected and / or predicted SSB beams, or a combination of SSBs actually transmitted and skipped. For example, a WTRU may be configured to transmit a PRACH preamble on multiple resources corresponding to the detection and / or prediction of multiple SSB beams (e.g., based on a received configuration for a detected SSB, e.g., based on the direction of the detected SSB). For example, a first resource may indicate that both the detected SSB beam and a first predicted SSB beam are preferred beams, a second resource may indicate that the detected SSB beam and a second predicted SSB beam are preferred beams, and so on. If a gNB receives a PRACH on a resource corresponding to an SSB beam that was not actually transmitted, the gNB may infer that the SSB beam may have been selected based on prediction.

[0072] The WTRU may monitor the PDCCH scrambled with RA-RNTI to detect RARs within the RAR-Window period corresponding to the transmitted PRACH and / or associated detected and / or predicted SSB beams. If the WTRU receives an RAR, it may continue with its initial access (e.g., sending Msg3).

[0073] This specification describes embodiments relating to the operation of a WTRU in the event of a PRACH transmission failure. For example, a WTRU may receive, or consist of, a transmitted SSB beam or a set of actually transmitted SSBs and a set of predicted SSB beams. The predicted SSBs may not be transmitted by the base station. The WTRU may select a predicted beam or predicted SSB (e.g., based on a predicted RSRP) and perform initial access to it (e.g., PRACH preamble transmission). The WTRU may transmit a PRACH preamble or a random access preamble using the beam associated with the predicted beam or predicted SSB. In one example, the WTRU may monitor a PDCCH scrambled with RA-RNTI to schedule RARs in order to detect RARs within a period RAR-Window corresponding to the transmitted PRACH and / or associated detected and / or predicted SSB beams. If the WTRU receives an RAR, it may continue with initial access (e.g., transmission of Msg3). If the WTRU does not receive a RAR within a set time frame or based on a counter, the WTRU may employ one or more of the following methods: In one method, the WTRU may switch to another SSB beam from a list of predicted SSB beams (e.g., selected in descending order of RSRP), sequentially switching up to a maximum of k beams, or select another predicted SSB and transmit a random access preamble using the beam associated with that predicted SSB. The set of predicted SSBs may be sorted in descending order of Reference Signal Received Power (RSRP), and predicted SSBs are selected from the sorted list. In one method, the WTRU may transmit a PRACH (e.g., only) for the detected beam, or select an actually transmitted SSB and transmit a random access preamble using the beam associated with that actually transmitted SSB. In one method, the WTRU may wait for a legacy SSB burst when each SSB beam is transmitted, or receive subsequent SSB bursts.For example, a gNB may transmit SSB bursts at longer intervals when transmitting each intended SSB beam (ssb-SetA). For instance, after M SSB bursts, including skipped SSB beams, the gNB transmits an SSB burst when transmitting each intended beam. Subsequent SSB bursts may include actual transmissions of SSBs that were actually transmitted and actual transmissions of predicted SSBs. Based on the subsequent SSB bursts, the WTRU may wait for up to M SSB bursts (e.g., M is set in MIB or SIB1) before detecting and selecting the optimal SSB beam or new SSB for initial access. In one method, the WTRU may reject this cell and attempt to detect or select a different synchronous raster and / or a different SSB block in a different cell for initial access.

[0074] Embodiments of the modification and verification procedures for the predicted beam based on the received RAR are described herein. For example, a WTRU may determine, based on the detected and / or received SSB beam and the AIML model, that the predicted SSB beam is the best beam (e.g., based on the predicted RSRP). The WTRU may initiate the initial access procedure by transmitting a PRACH preamble for the predicted SSB beam (e.g., in the time and frequency resources associated with the predicted SSB beam). The WTRU may monitor the RAR window to receive the received RAR.

[0075] In one example, a WTRU may measure the RSRP after receiving a RAR (e.g., a RAR PDCCH and / or RAR PDSCH on a beam QCLed with a predicted SSB beam) (e.g., based on a reference signal in the RAR message, e.g., DMRS). The WTRU may compare the measured RSRP based on the received RAR to the predicted RSRP for the predicted SSB. For example, the WTRU may be set or received (e.g., via MIB, SIB1, and / or RAR) one or more parameters relating to an offset and / or threshold for comparing the RSRP measured based on the RAR (e.g., PDCCH DMRS or PDSCH DMRS) with the RSRP predicted for SSB. For example, the difference in RSRP measured from SSB and DMRS may be a motivating factor here. Also, there may be a significant difference in the transmit power between SSB and DMRS. Therefore, the gNB may provide an offset / threshold (e.g., 10 dB) for comparing the values.

[0076] In one example, the WTRU may verify the accuracy of the prediction based on the comparison results and one or more offsets or thresholds (for example, determining whether the difference between the predicted RSRP and the measured RSRP is below a threshold (e.g., 10 dB)). For example, if the difference between the predicted RSRP and the measured RSRP is less than a (pre-set) threshold, the WTRU may determine that the predicted beam is sufficiently accurate and therefore may continue to use the predicted beam for the transmission of further signals (e.g., Msg3). For example, if the difference between the predicted RSRP and the measured RSRP is greater than a (pre-set) threshold, the WTRU may determine that the predicted beam is not sufficiently accurate. The WTRU may reject the predicted beam and continue selecting another beam, or follow the appropriate procedure in case of PRACH transmission failure.

[0077] In one example (for instance, alternatively), if the WTRU transmits a PRACH based on multiple (e.g., two) SSB beam combinations detected and / or predicted (as described later), the WTRU may receive multiple (e.g., two) RAR messages for the corresponding beams. For example, the WTRU may measure the RSRP of each received RAR message and determine the optimal beam (e.g., the beam with the higher RSRP), and based on the selected optimal beam, the WTRU may transmit further signals (e.g., message 3).

[0078] Regarding the embodiments proposed herein, there are aspects common to all embodiments described below. Artificial intelligence (AI) can be defined as the behavior exhibited by machines. Such behavior may mimic cognitive functions such as sensing, reasoning, adapting, and acting. Machine learning (ML) can refer to a type of algorithm that solves problems based on learning through experience ("data") without being explicitly programmed ("composing a set of rules"). Machine learning can be considered a subfield of AI. Different machine learning paradigms can be assumed depending on the nature of the data and feedback available to the learning algorithm. For example, a supervised learning approach may relate to learning a function that maps inputs to outputs based on labeled training examples, where each training example may consist of a pair of inputs and corresponding outputs. For example, an unsupervised learning approach may relate to detecting patterns in data that are not prelabeled. For example, a reinforcement learning approach may relate to performing a set of actions in an environment to maximize cumulative rewards. In some solutions, it is possible to apply machine learning algorithms by combining or interpolating the above approaches. For example, a semi-supervised learning approach may use a combination of small amounts of labeled data and large amounts of unlabeled data during learning. In this respect, semi-supervised learning lies between unsupervised learning (without labeled training data) and supervised learning (with labeled training data). Deep learning (DL) can refer to a class of machine learning algorithms that employ artificial neural networks (especially deep neural networks: DNNs) that are broadly inspired by biological systems. A deep neural network (DNN) is a special machine learning model inspired by the human brain, where the input is linearly transformed and passes through a nonlinear activation function multiple times. DNNs typically consist of multiple layers, each consisting of a linear transformation and a predetermined nonlinear activation function. DNNs can be trained from training data using a backpropagation algorithm. In recent years, DNNs have demonstrated state-of-the-art performance in diverse domains such as speech, vision, and natural language, and in various machine learning settings such as supervised, unsupervised, and semi-supervised.The term AIML-based methods / processes can refer to the realization of actions and adaptation to requirements through data-driven learning without explicitly setting the sequence of actions. Such methods can enable the learning of complex actions that are difficult to specify or implement using conventional methods.

[0079] A WTRU may transmit and receive a physical channel or reference signal according to at least one spatial domain filter. The term “beam” may be used to refer to a spatial domain filter. A WTRU may transmit a physical channel or signal using the same spatial domain filter used to receive an RS (e.g., CSI-RS) or SS block. The WTRU transmission may be called the “target,” and the received RS or SS block may be called the “reference” or “source.” In this case, it can be said that the WTRU transmits the target physical channel or signal according to a spatial relationship that references the RS or SS block. A WTRU may transmit a first physical channel or signal according to the same spatial domain filter used to transmit a second physical channel or signal. The first and second transmissions may be called the “target” and “reference” (or “source”), respectively. In this case, it can be said that the WTRU transmits the first (target) physical channel or signal according to a spatial relationship that references the second (reference) physical channel or signal. Spatial relationships may be implicit, established by RRC, or signaled by MAC CE or DCI. For example, a WTRU may implicitly transmit the DM-RS of PUSCH and PUSCH according to the same spatial domain filter as the SRS indicated by the SRI shown in the DCI or set by the RRC. In another example, a spatial relationship may be set by the RRC for the SRS Resource Indicator (SRI) or signaled by the MAC Control Element (CE) for PUCCH. Such a spatial relationship may also be called a “beam indication”. A WTRU may receive a first (target) downlink channel or signal according to the same spatial domain filter or spatial receive parameters as the second (reference) downlink channel or signal. For example, such an association may exist between physical channels such as PDCCH and PDSCH and their corresponding DM-RS. Such an association may exist when a WTRU is configured in quasi-co-location (QCL) assumption type D between corresponding antenna ports, provided that at least the first and second signals are reference signals.Such associations can be configured as TCI (Transmission Configuration Indicator) states. The WTRU may be notified of the association between a CSI-RS or SS block and a DM-RS by indexing to a set of TCI states set by the RRC and / or notified by the MAC control element. Such notifications are sometimes referred to as "beam notifications."

[0080] In this specification, TRP (e.g., transmit / receive point) may be used interchangeably with one or more TP (transmitting point), RP (receiving point), RRH (radio remote head), DA (distributed antenna), BS (base station), BS sector, and / or cell (e.g., geographic cell area served by BS). In this specification, multi-TRP may be used interchangeably with MTRP, M-TRP, and one or more multiple TRPs.

[0081] A WTRU may report a subset of Channel Status Information (CSI) components, which may include at least the CSI-RS Resource Index (CRI), SSB Resource Index (SSBRI), panel indications used for reception in the WTRU (such as panel identifiers or group identifiers), L1-RSRP, L1-SINRs obtained from SSB or CSI-RS (e.g., cri-RSRP, cri-SINR, ssb-Index-RSRP, ssb-Index-SINR), and rank index (RI), channel quality index (CQI), precoding matrix index (PMI), layer index (LI), and / or other channel status information.

[0082] A WTRU may receive a synchronization signal / physical broadcast channel (SS / PBCH) block. The SS / PBCH block (SSB) may include the primary synchronization signal (PSS), secondary synchronization signal (SSS), and physical broadcast channel (PBCH). The WTRU may monitor, receive, or attempt to decode the SSB during initial access, initial synchronization, radio link monitoring (RLM), cell search, cell switching, etc.

[0083] The WTRU may measure and report Channel Status Information (CSI), and the CSI for each connection mode may include, or consist of, one or more CSI Report Configurations, CSI-RS Resource Sets, and / or NZP CSI-RS Resources. The CSI Report Configuration may include one or more CSI Report Quantities (e.g., Channel Quality Indicator (CQI), Rank Indicator (RI), Pre-Coding Matrix Indicator (PMI), CSI-RS Resource Indicator (CRI), Layer Indicator (LI), etc.), CSI Report Types (e.g., aperiodic, semi-persistent, periodic), CSI Report Codebook Configurations (e.g., Type I, Type II, Type II port selection, etc.), and / or CSI Report Frequencies. A CSI-RS resource set may include one or more of the following: CSI resource settings, NZP-CSI-RS resources for channel measurement, NZP-CSI-RS resources for interference measurement, and / or CSI-IM resources for interference measurement. An NZP CSI-RS resource may include one or more of the following: NZP CSI-RS resource ID, periodicity and offset, QCL information and TCI status, and / or resource mapping (e.g., number of ports, density, CDM type, etc.).

[0084] For example, a WTRU may indicate, determine, or construct one or more reference signals. Based on each reference signal, a WTRU may monitor, receive, and measure one or more parameters. For example, one or more of the following may apply. The following parameters are non-exclusive examples of parameters that may be included in the measurement of a reference signal. One or more of these parameters may be included. Other parameters may also be included.

[0085] The SS-RSRP (SS-RSRP) can be measured based on a synchronization signal (e.g., a demodulated reference signal (DMRS) in a PBCH or SSS). It can be defined as a linear average of the power contributions of the resource elements (REs) transmitting each synchronization signal. Power scaling of the reference signal may be necessary when measuring RSRP. When using SS-RSRP for L1-RSRP, the measurement may be performed based on a CSI reference signal in addition to the synchronization signal. The CSI-RSRP can be measured based on a linear average of the power contributions of the resource elements (REs) transmitting the corresponding CSI-RS. The CSI-RSRP measurement can be configured within the measurement resources for a given CSI-RS opportunity. The SS-SINR (SS-SINR) can be measured based on a synchronization signal (e.g., a DMRS or SSS in a PBCH). It is defined as the linear average of the power contributions of the resource elements (REs) transmitting the corresponding synchronization signal divided by the linear average of the noise and interference power contributions. When SS-SINR is used as L1-SINR, noise and interference power measurements may be performed based on the resources configured in the upper layers. CSI-SINR can be measured based on the linear average of the power contributions of the resource elements (REs) transmitting the corresponding CSI-RS divided by the linear average of the noise and interference power contributions. When CSI-SINR is used as L1-SINR, noise and interference power measurements may be performed based on the resources configured in the upper layers. Otherwise, noise and interference power can be measured based on the resources transmitting the corresponding CSI-RS.

[0086] The Received Signal Strength Indicator (RSSI) can be measured based on the average of the total power contributions in the configured OFDM symbol and bandwidth. Power contributions can be received from different resources (e.g., service and non-service cells in the same channel, adjacent channel interference, thermal noise, etc.). The Cross-Layer Interference Received Signal Strength Indicator (CLI-RSSI) can be measured based on the average of the total power contributions of the configured OFDM symbol in the configured time and frequency resources. Power contributions can be received from different resources (e.g., cross-layer interference, service and non-service cells in the same channel, adjacent channel interference, thermal noise, etc.). The Distancing Reference Signal Received Power (SRS-RSRP) can be measured based on the linear average of the power contributions of the resource elements (REs) transmitting each SRS. The Secondary Synchronization Signal Reference Signal Received Quality (SS-RSRQ) can be measured based on the measured values ​​of the Reference Signal Received Power (SS-RSRP) and Received Signal Strength (RSSI). In one example, SS-RSRQ can be calculated as the ratio N × SS-RSRP / NR carrier RSSI, where N can be determined based on the number of resource blocks within the corresponding NR carrier RSSI measurement bandwidth. Therefore, the measurements used in the numerator and denominator can be performed on the same set of resource blocks. CSI reference signal received quality (CSI-RSRQ) can be measured based on the measured values ​​of reference signal received power (CSI-RSRP) and received signal strength (RSSI). In one example, SS-RSRQ can be calculated as the ratio N × CSI-RSRP / CSI-RSSI, where N can be determined based on the number of resource blocks present within the corresponding CSI-RSSI measurement bandwidth. Therefore, the measurements used in the numerator and denominator can be performed on the same resource block.

[0087] In one example, a CSI report configuration (e.g., CSI-ReportConfigs) is associated with a single BWP (e.g., indicated by BWP-Id), and one or more parameters are set, such as CSI-RS resources and / or CSI-RS resource sets for channel and interference measurements, CSI-RS report configuration type (including periodic, semi-persistent, and aperiodic), CSI-RS transmit periodicity for periodic and semi-persistent CSI reports, CSI-RS transmit slot offset for periodic, semi-persistent, and aperiodic CSI reports, CSI-RS transmit slot offset list for semi-persistent and aperiodic CSI reports, time limits for channel and interference measurements, report frequency band configuration (broadband / subband CQI, PMI, etc.), thresholds and calculation modes for reported quantities (CQI, RSRP, SINR, LI, RI, etc.), codebook configuration, group-based beam report, CQI table, subband size, non-PMI port display, and port index.

[0088] In one example, a CSI-RS resource set (e.g., NZP-CSI-RS-ResourceSet) may include one or more CSI-RS resources (e.g., NZP-CSI-RS-Resource and CSI-ResourceConfig), and the WTRU may consist of one or more references to TCI states, including the CSI-RS periodicity and slot offset for periodic and semi-persistent CSI-RS resources, the number of CSI-RS ports, density, CDM type, OFDM symbol, subcarrier occupancy, the bandwidth portion to which the configured CSI-RS is allocated, and / or the QCL source RS and the corresponding QCL type.

[0089] In one example, an RS resource set may use one or more of the following configurations. For example, a WTRU may consist of one or more RS resource sets. An RS resource set configuration may include one or more of the following: an RS resource set ID, one or more RS resources for the RS resource set, repetition (e.g., on or off), a non-periodic trigger offset (e.g., any of slots 0 to 6), and / or TRS information (e.g., true or false).

[0090] One or more of the following configurations may be used for an RS resource. For example, a WTRU may consist of one or more RS resources. An RS resource configuration may include one or more of the following: RS resource ID, resource mapping (e.g., RE in PRB), power control offset (e.g., a value of -8, ..., 15), power control offset with SS (e.g., -3dB, 0dB, 3dB, 6dB), scrambling ID, periodicity and offset, and / or QCL information (e.g., based on TCI status).

[0091] In the following, the properties of a grant or assignment may consist of at least one of the following parameters provided by DCI, MAC, or RRC for scheduling a grant or assignment: frequency allocation, time allocation mode (e.g., duration), priority, modulation coding scheme, transport block size, number of space layers, number of transport blocks, TCI state, CRI or SRI, number of repetitions, whether the repetition scheme is type A or type B, whether the grant is a set grant type 1, type 2, or dynamic grant, whether the assignment is a dynamic assignment or a semi-persistent scheduling (set) assignment, a set grant index or semi-persistent assignment index, periodicity of the set grant or assignment, channel access priority class (CAPC), and / or any parameters provided by DCI, MAC, or RRC for scheduling a grant or assignment.

[0092] In the following, instructions by DCI may consist of explicit instructions by DCI fields, or explicit instructions by RNTI used to mask or scramble the CRC of DCI, and / or implicit instructions by properties such as DCI format, DCI size, core set or search space, aggregation level, and the first resource element of the incoming DCI (e.g., the index of the first control channel element), and the property-value mapping may be communicated by RRC or MAC. Receiving or monitoring DCI with or using RNTI may mean that the CRC of DCI is being masked or scrambled by RNTI.

[0093] In this specification, the signal may be used interchangeably with one or more of the following: depth sounding reference signals (SRS), channel status information-reference signals (CSI-RS), demodulation reference signals (DM-RS), phase tracking reference signals (PT-RS), and / or synchronization signal blocks (SSB).

[0094] In this specification, a channel may be used interchangeably with one or more physical downlink control channels (PDCCH), physical downlink sharing channels (PDSCH), physical uplink control channels (PUCCH), physical uplink sharing channels (PUSCH), physical random access channels (PRACH), and / or similar channels.

[0095] In this specification, signals, channels, and messages (for example, as DL or UL signals, channels, and messages) may be used interchangeably. In this specification, RS may be used interchangeably with one or more RS resources, RS resource sets, RS ports, and RS port groups. In this specification, RS may be used interchangeably with one or more SSB, CSI-RS, SRS, DM-RS, TRS, PRS, and PTRS.

[0096] In this specification, time instances, slots, symbols, and subframes may be used interchangeably. In this specification, the terms SSB, SS / PBCH block, PSS, SSS, PBCH, and MIB may be used interchangeably. In this specification, SSB, SSB beam, and SSB index may be used interchangeably. In this specification, the proposed solution for beam resource prediction may be used for beam resources belonging to one or more cells, as well as for one or more TRPs.

[0097] In this specification, CSI reports may be used interchangeably with CSI measurements, beam reports, and beam measurements. In this specification, RS resource sets may be used interchangeably with beam groups.

[0098] Embodiments described herein may share initial common embodiment components, such as SS / PBCH blocks, MIBs and SIBs, the configuration of measurement and estimation sets, and the requirements for set B. In one embodiment, a WTRU may receive a physical broadcast channel (PBCH). The PBCH may be part of an SS / PBCH block (SSB). The PBCH may transmit system information. The PBCH may contain or transmit a Master Information Block (MIB). The term MIB may be used to represent the content, information, payload, and / or bits transmitted by the PBCH. PBCH and MIB may be used interchangeably herein. For example, upon detection and / or reception of an SS / PBCH block, the WTRU may use information in the MIB regarding time and / or frequency resources to locate one or more System Information Blocks (SIBs). The term SIB may be used to represent the content, information, payload, and / or bits. For example, one or more cell (re)selection parameters may be broadcast in an SIB (e.g., SIB1, SIB2, SIB3, etc.), and a WTRU may detect and / or receive them from the service cell and / or newly discovered cell.

[0099] In one embodiment, a WTRU may consist of one or more sets of reference signal (RS) resources and / or beams (or beam pairs). Each RS resource or beam or beam pair may be associated with a transmission from a beam having specific beam parameters (e.g., beam direction and beam width). The WTRU may consist of the associated beams and / or RS resources and beam parameters. In one example, the WTRU may consist of a first set of RS resources or beams or beam pairs that can cover an entire RS resource space or beam space or beam pair space. The WTRU determines or selects SetA and SetB, and the sum of SetA and SetB may cover an entire RS resource space, beam space, or beam pair space. For example, SetA and SetB may be mutually exclusive. In one example, SetB may include RS resources for which the WTRU performs measurements to obtain 1) direct measurements for a first set of beams or beam pairs (e.g., a one-to-one correspondence between RS resources and beams or beam pairs), and 2) estimated measurements for a second set of beams or beam pairs (e.g., a many-to-one correspondence between RS resources and beams or beam pairs, which may include the use of an AI / ML estimation model).

[0100] In one embodiment, a WTRU may be configured with one or more sets of RS resources associated with each beam. For example, a WTRU may be configured with a first beam associated with two RS sets, a first set containing a single RS resource and a second set containing multiple RS resources. The WTRU may determine the measurements associated with the beam through direct measurements of the RS resources in the first set or through estimates obtained from measurements of the RS resources in the second set. For all beams for which measurements need to be obtained (directly or by estimation), the WTRU may determine a set of RS resource measurements (e.g., SetB) such that SetB contains at least one of the two RS resource sets associated with that beam. In this specification, SetB may be used interchangeably with one or more sets of RS resource sets, beams, beam pairs, beam RS resources, RS resources, and / or beam patterns. In this specification, SetA may be used interchangeably with one or more sets of RS resource sets, beams, beam pairs, beam RS resources, RS resources, and / or beam patterns.

[0101] Initial access may be performed in an AIML system with skipped SSBs. In one embodiment, in a system with skipped SSBs, sets of SSBs designated as SetA and SetB may be determined. The WTRU may be (pre-configured) to have a maximum number of SSBs in a cell (e.g., in an SSB burst). The maximum number of SSBs may be explicitly set for the WTRU (e.g., via MIB, SIB, etc.). Alternatively, the maximum number of SSBs may be implicitly indicated to the WTRU based on the operating frequency band, etc. For example, if the WTRU is operating in a first frequency band (e.g., FR1), the WTRU may determine the maximum number of SSBs in an SSB burst to be a first value (e.g., a maximum of 8 SSBs), if the WTRU is operating in a second frequency range (e.g., FR2), the WTRU may determine the maximum number of SSBs in an SSB burst to be a second value (e.g., a maximum of 64 SSBs), and so on.

[0102] A WTRU may detect one or more SSBs within an SSB burst (e.g., during initial access, cell (re)selection, etc.). In one example, considering the maximum number of SSBs in an SSB burst, a subset of SSBs used in an SSB burst (e.g., within a cell) may actually be planned, configured, requested, expected, and / or designed. The planned set of SSBs may be a set of SSBs that can cover the entire SSB resource space or beam space. For example, the number of planned SSBs may be less than or equal to the maximum number of SSBs determined by the network based on the SSB coverage space, beam correlation, etc. A WTRU may be provided for and / or configured for the number of planned SSBs and / or the corresponding SSB beam index, in which case the WTRU may consider the planned set of SSBs as SetA.

[0103] The WTRU may receive, provide, or set information about the SSBs actually transmitted within an SSB burst. This information may include the number of SSB beams actually transmitted, the SSB index corresponding to the transmitted SSB beams, and so on. The WTRU may consider the set of actually transmitted SSBs as SetB, which may be a subset of the configured SetA. In one example (for example, alternatively), the WTRU may determine, provide, or set a set of skipped SSBs that were not actually transmitted within the corresponding SSB burst, which are a subset of SetA. In one example, the sum of SetB and the set of skipped beams may be equal to SetA.

[0104] Figure 2 shows an example of system 200 with skipped SSBs. For example, as shown in Figure 2, the solid beam represents Set B, i.e., the beam that was actually transmitted, the dashed beam represents the skipped beam, and Set A is the sum of Set B and the skipped beam. "Transmitted SSB" and "Actual transmitted SSB" can be used interchangeably. "Untransmitted SSB" and "Skipped SSB" can be used interchangeably.

[0105] In a system with skipped SSBs, procedures may be performed to predict the SSB beam. For example, a WTRU may perform one or more of the following: The WTRU may detect one or more SSBs (e.g., at initial access) or receive instructions indicating one or more sets of SSBs actually transmitted within an SSB burst. The WTRU may select a first SSB with the highest received power (e.g., RSRP). The WTRU may determine time and frequency synchronization based on the first SSB. The WTRU may decode PSS, SSS, PBCH, PBCH-DMRS, SSB index, MIB, and SIB1 for the first SSB. The WTRU may receive a setting (e.g., via MIB or SIB1) indicating whether SSB skipping is enabled in the gNB or receive instructions indicating one or more sets of skipped SSBs within an SSB burst. The WTRU may receive a list of each SSB set by the gNB (e.g., SetA) (e.g., via ssb-SetA in SIB1). The WTRU may receive a list of SSBs being transmitted (e.g., SetB) (e.g., via ssb-SetB and / or ssb-PositionsInBurst in SIB1). The WTRU may receive configuration information (ssb-SetB) associated with each SSB being transmitted, which includes a list of candidate beams (e.g., ssb-candidate) that the WTRU can use as inference input, and includes information about the association between one or more SSBs being transmitted and one or more SSBs that are not being transmitted. The list of candidate beams may include beams associated with the untransmitted SSBs. The set of candidate beams may be shown for each SSB beam in SetB. The configuration information may include beam index, azimuth angle, elevation angle, aiming angle, etc. In one example, for each transmitted SSB beam from ssb-SetB, the WTRU may receive a list of candidate SSB beams (e.g., ssb-candidate), where the candidate beams are a subset of SetA. Based on the candidate SSB beamlist (ssb-candidate), WTRU can determine which SSB beams are associated (e.g., adjacent, nearby, correlated) with the beams detected from ssb-SetB.The WTRU can predict a set / list of N (optimal) predicted SSB beams from a list of untransmitted SSB beams using an AIML model. The number of beams that can be predicted may depend on the AIML model. The WTRU can select k optimal SSB beams using the predicted list of N beams along with the received candidate SSB beam list (e.g., ssb-candidate). The k optimal SSB beams in the list may be ordered (e.g., based on descending order of RSRP, RSRQ, etc.) with respect to the predicted SSB beams based on the AIML model. The set of predicted SSBs may be sorted in descending order of Reference Signal Received Power (RSRP), and predicted SSBs may be selected from the sorted list. The WTRU may initiate initial access on the PRACH resource (e.g., by transmitting a PRACH preamble). The WTRU may receive one or more informational constructs regarding one or more SSB-specific (e.g., beam-specific) parameters (e.g., paging search space) for the predicted SSB as part of the initial access procedure (e.g., via RAR, Msg4, and / or MsgB). The gNB may be aware that the WTRU predicted the predicted SSB based on the received PRACH because the corresponding SSB was never transmitted in the first place.

[0106] The WTRU may support initial access procedures based on predicted quality (e.g., predicted RSRP) and measured quality (e.g., measured RSRP). The WTRU may detect one or more SSBs (during initial access) and first select the highest quality SSB (e.g., received power (RSRP), RSRQ, SINR, hypothetical BLER). The number of first SSBs may be determined based on one or more of the quality thresholds, a predefined maximum number, and / or the capabilities of the UE.

[0107] The number of first SSBs may be determined based on a quality threshold. For example, a WTRU may determine one or more SSBs that have a quality higher than the threshold. The threshold may be predetermined or set (e.g., by a gNB). The number of first SSBs may be determined based on a predetermined maximum number. For example, the maximum number of SSBs to be determined (e.g., M1) may be predetermined or set. For example, if the number of SSBs with a quality higher than the threshold is M2 and this is greater than M1, the WTRU may determine the optimal M1 SSBs from among the M2 SSBs. The number of first SSBs may be determined based on the capabilities of the UE. For example, the maximum number of determined SSBs (e.g., M3) may be limited based on the capabilities of the WTRU. For example, if the number of SSBs with a quality higher than the threshold is M2 and this is greater than M3, the WTRU may determine the optimal M3 SSBs from among the M2 SSBs.

[0108] The WTRU may determine time and frequency synchronization based on a first SSB number. Based on the determined time and frequency synchronization, the WTRU may decode one or more initial access-related signals (e.g., PSS, SSS, PBCH, PBCH-DMRS, SSB index, MIB, and SIB1) for the first SSB number. Based on the decoded one or more initial access-related signals, the WTRU may receive a setting (e.g., via MIB or SIB1) indicating whether SSB skipping is enabled in the gNB.

[0109] The gNB may indicate, based on one or more of the MIB, SIB, RRC, MAC CE, and DCI, whether SSB skipping is enabled or disabled, the type of AI / ML model, the number of SSBs in Set A for initial access (e.g., including the number of planned SSBs, skipped SSBs, and transmitted SSBs), the SSB list for Set A for initial access (e.g., the planned SSB list, e.g., ssb-via-SetA), the list for Set B for initial access (e.g., the list of SSBs transmitted or skipped for initial access, e.g., ssb-via-SetB), supplementary information for transmitted or skipped SSBs, the number of transmitted or skipped SSBs, the pattern of transmitted SSBs, beam angle related information, and / or one or more of the associated SSBs.

[0110] In one example, the gNB may indicate one or more of the following based on whether SSB skipping is enabled or disabled. For example, a flag (e.g., 1 bit) may be supported (e.g., 0 indicates that SSB skipping is not supported, and 1 indicates that SSB skipping is supported). Based on this indication, the WTRU may determine the operating mode for initial access. For example, if the WTRU receives an indication that SSB skipping is not supported, the WTRU may determine an initial access procedure without SSB skipping. In one example, if the WTRU receives an indication that SSB skipping is supported, the WTRU may determine an initial access procedure with SSB skipping. The WTRU may decide to send an indication that it wants to utilize some of the skipped SSBs during or after the initial access procedure. In one example, this indication may be implicit (e.g., based on the number of SSBs for initial access). For example, if the number of SSBs indicated (or determined) for initial access is less than (or equal to) a threshold (e.g., 32), the WTRU may determine a first operating mode (e.g., no SSB skipping). If the number of SSBs allocated (or determined) for the initial access is greater than a threshold, the WTRU may determine a second operating mode (e.g., SSB skipping). In another example, this indication may be implicit (e.g., based on the number of skipped SSBs). For example, if the indicated (or determined) number of skipped SSBs is X (e.g., 0), the WTRU may determine a first operating mode (e.g., no SSB skipping). Otherwise, the WTRU may determine a second operating mode (e.g., SSB skipping). The number of skipped SSBs may be determined as: Number of skipped SSBs = Number of SSBs at initial access - Number of transmitted SSBs.

[0111] In one example, a gNB may indicate one or more of the following based on the type of AI / ML model: A WTRU may receive an indication indicating the type of AI / ML model for initial access. For example, a WTRU may receive a flag indication with a first value (e.g., value 0) that may indicate a first AI / ML model type, and a flag indication with a second value (e.g., value 1) that may indicate a second AI / ML model type. In another example, a flag indication with a first value (e.g., value 0) may indicate no AI / ML model to use for initial access, a flag indication with a second value (e.g., value 1) may indicate a first type of AI / ML model, a flag indication with a second value (e.g., value 2) may indicate a second type of AI / ML model, a flag indication with a fourth value (e.g., value 3) may indicate a third type of AI / ML model, and so on.

[0112] In one example, the gNB may indicate one or more of the following based on the number of SSBs in SetA during the initial access (e.g., including the planned number of SSBs, skipped SSBs, and transmitted SSBs): The WTRU may receive an instruction regarding the number of SSBs in SetA during the initial access. For example, the WTRU may receive an instruction (e.g., 2 bits, 0 indicating 16 SSBs, 1 indicating 32 SSBs, 2 indicating 64 SSBs, 3 indicating 128 SSBs). In one example, the WTRU may blindly determine the number of SSBs for the initial access based on the number of transmitted SSBs. For example, if the number of transmitted SSBs is equal to the number of SSBs in SetA, or if the number of transmitted SSBs is a ratio of the number of SSBs in SetA (e.g., half, one-third, one-quarter, etc.).

[0113] In one example, the gNB may indicate one or more of the following based on the list of SSBs in SetA for initial access (e.g., a planned SSB list, e.g., ssb-SetA): The WTRU may receive instructions regarding the SSBs in SetA to be used for initial access. For example, the WTRU may receive a bitmap of the SSBs. If the bit corresponding to an SSB in the bitmap indicates a first value (e.g., value 0), the corresponding SSB may not be used for initial access. If the bit indicates a second value (e.g., value 1), the corresponding SSB may be used for initial access. The payload size of this instruction may depend on the frequency range of the operating cell. For example, if the frequency range is less than or equal to X1, the payload size may be F0 bits (e.g., 4 bits). If the frequency range is higher than X1 and less than or equal to X2, the payload size may be F1 bits (e.g., 8 bits), and if the frequency range is higher than X2, the payload size may be F2 bits (e.g., 64 bits). X1, X2, F0, F1, and F2 may be predefined or semi-statistically set, and this instruction may be based on an existing field (e.g., within the SIB and / or MIB). For example, the field "ssb-PositionsInBurst" may be used for the instruction. For example, if the WTRU receives an instruction for the operating mode and determines a first mode (e.g., SSB skip not supported), the WTRU may use "ssb-PositionsInBurst" for the SSB instruction in SetA during initial access.

[0114] In one example, a gNB may indicate one or more of the following based on a SetB list for initial access (e.g., a list of transmitted or skipped SSBs for initial access, e.g., via ssb-SetB): A WTRU may receive instructions on which SSBs are skipped or transmitted. For example, a WTRU may receive a bitmap corresponding to the transmitted or skipped SSBs. If the bit related to an SSB in the bitmap indicates a first value (e.g., value 0), the corresponding SSB is not transmitted. If the bit indicates a second value (e.g., value 1), the corresponding SSB may be transmitted. The payload size of the instructions may depend on the frequency range of the cell under operation. For example, if the frequency range is less than or equal to X1, the payload size may be F0 bits (e.g., 4). If the frequency range is higher than X1 and less than or equal to X2, the payload size may be F1 bits (e.g., 8 bits). If the frequency range is higher than X2, the payload size may be F2 bits (e.g., 64 bits), and X1, X2, F0, F1, and F2 may be predefined or semi-statistically set. This instruction may be based on an existing field (e.g., within the SIB and / or MIB). For example, the field "ssb-PositionsInBurst" may be used for the instruction. For example, if a WTRU receives an instruction for the operating mode and decides on a second mode (e.g., SSB skip), the WTRU may use "ssb-PositionsInBurst" for the instruction of SetB (e.g., transmitted or skipped SSB).

[0115] As an example, a gNB may indicate one or more of the following based on the supplementary information of transmitted or skipped SSBs: A WTRU may determine the association between one or more beam IDs and SSBs. This association may be based on beam information configured by the gNB and / or beam information reported by the WTRU. This association may be based on one or more of the following: explicit designation, beam direction order, and / or panel and / or TRP (CORESET group ID) order.

[0116] For example, the association between one or more beam IDs and SSBs may be based on explicit designation. A WTRU may receive explicit designation of beam IDs for each SSB (e.g., based on the configuration of beam information). For example, a WTRU may consist of one or more beam IDs, each beam ID may include one or more beam information (e.g., beam direction, beam width, panel, and / or TRP ID).

[0117] For example, the association between one or more beam IDs and SSBs may be based on the order of beam directions. Beam IDs may be associated with SSBs based on the direction of the SSB. For example, a first beam ID may be associated with an SSB in a beam direction having the minimum and / or maximum angle (e.g., 5 degrees), and a second beam ID may be associated with an SSB in a beam direction having the second minimum and / or maximum angle, and so on.

[0118] For example, the association between one or more beam IDs and an SSB may be based on the order of the panels and / or TRPs (CORESET group ID). A beam ID may be associated with the order of the panels and / or TRPs that make up the SSB. Various patterns are possible, such as a first beam ID being associated with an SSB containing a first panel and / or TRP, and a second beam ID being associated with an SSB containing a second panel and / or TRP.

[0119] A WTRU may receive an instruction indicating the number of SSBs transmitted or skipped. For example, a WTRU may receive an instruction (e.g., a 2-bit instruction, e.g., 0 indicates 8 SSBs, 1 indicates 16 SSBs, 2 indicates 32 SSBs, 3 indicates 64 SSBs). The payload size of the instruction may be determined based on the number of SSBs transmitted or skipped during the initial access. For example, if the total number of transmitted or skipped SSBs is less than or equal to Y, the payload size may be N1 bits (e.g., 1 bit). If the total number of transmitted or skipped SSBs is greater than Y, the payload size may be N2 bits (e.g., 2 bits). In one example, a WTRU may blindly determine the number of skipped SSBs during the initial access based on the number of transmitted SSBs.

[0120] In one example, a WTRU may implicitly indicate the number of transmitted or skipped SSBs based on the pattern of transmitted SSBs. For instance, if the pattern is the first pattern, the WTRU may determine the first number of transmitted or skipped SSBs. If the pattern is the second pattern, the WTRU may determine the second number of transmitted or skipped SSBs.

[0121] In one example, the WTRU may implicitly indicate the number of SSBs transmitted or skipped based on the supported AI / ML model for initial access and / or beam prediction. For example, if the AI / ML model is the first AI / ML model, the WTRU may determine the first number of transmitted or skipped SSBs. If the AI / ML model is the second AI / ML model, the WTRU may determine the second number of transmitted or skipped SSBs.

[0122] A WTRU may receive instructions regarding the pattern of a transmitted SSB. For example, a WTRU may receive instructions (e.g., a 2-bit instruction, e.g., 0 indicates pattern #1, 1 indicates pattern #2, 2 indicates pattern #3, and 3 indicates pattern #4). The pattern of this instruction may be predetermined or semi-statically set. The payload size of the instruction may be determined based on the total number of planned SSBs (SetA), the number of transmitted SSBs (SetB), and / or the number of skipped SSBs. For example, if the total number of planned, transmitted, and / or skipped SSBs is less than or equal to Z, the payload size may be N3 bits (e.g., 1 bit). If the total number of planned, transmitted, and / or skipped SSBs exceeds Y, the payload size may be N4 bits (e.g., 2 bits).

[0123] The WTRU may receive one or more of the following pieces of information in relation to transmitted and / or skipped SSBs: The WTRU may receive an indication of the coverage area for each SSB for initial access (e.g., angular coverage area, such as 120 degrees). The WTRU may receive an indication of the coverage area for transmitted SSBs (e.g., angular coverage area, such as 120 degrees). The WTRU may receive an indication of the coverage area for skipped SSBs (e.g., angular coverage area, such as 60 degrees). The WTRU may receive an indication of the location, center, and / or direction (e.g., 0 degrees) of transmitted SSBs. The WTRU may receive an indication of the location, center, and / or direction (e.g., 0 degrees) of skipped SSBs.

[0124] The WTRU may receive an indication of the granularity of the transmitted SSB (e.g., 3 degrees). For example, the WTRU may receive one configuration for each of the horizontal and / or vertical regions. For example, the WTRU may indicate one configuration for each of the horizontal and / or vertical regions (e.g., through the WTRU function). For example, the WTRU may receive the granularity of the skipped SSB (e.g., 12 degrees). For example, the WTRU may receive one configuration for each of the horizontal and / or vertical regions. For example, the WTRU may indicate one configuration for each of the horizontal and / or vertical regions (e.g., through the WTRU function).

[0125] For some information, the display may be provided per direction (e.g., horizontal angle (or azimuth angle), vertical angle (or elevation angle), aiming angle, etc.). For some information, the display may be provided per WTRU and applied to each applicable direction.

[0126] The WTRU may receive configuration information (e.g., via SIB) for at least one of the detected SSB beams. In one example, this information may include a list of candidate skip SSB beams (ssb-candidate) associated with the corresponding detected SSB beam. In one example, this association may include beams that are adjacent, neighboring, and / or correlated with the detected beam from the transmitted beamlist (ssb-SetB). The configuration information for the candidate skip beams may include beam index, azimuth angle, elevation angle, aiming angle, etc. In one example, the WTRU may use the configured list of candidate skip beams to narrow down and / or determine the optimal candidate for SSB beam prediction.

[0127] The WTRU may determine which SSB beams (e.g., adjacent, close, correlated) are associated with a detected beam (e.g., from ssb-SetB) based on a set list of candidate SSB beams (e.g., ssb-candidate in the SIB). For example, a skipped SSB may be associated with a transmitted SSB that has an adjacent beam ID (e.g., a skipped SSB with beam ID X is associated with the SSB with beam ID X+d1 and / or X-d2) or with an adjacent order in the list (e.g., the Xth SSB is associated with the X+d1th SSB and the X-d2th SSB).

[0128] The WTRU may determine k optimal (e.g., predicted) SSB beams (e.g., based on the highest quality, such as RSRP, RSRQ, and hypothetical BLER) based on one or more of the above information. For example, the WTRU may select k optimal SSB beams by using a list of predicted beams and a list of received candidate SSB beams (e.g., ssb-candidate). The k optimal SSB beams in the list may be ordered (e.g., based on descending order, such as RSRP, RSRQ) with respect to the predicted SSB beams based on the AIML model. The set of predicted SSBs may be sorted in descending order of reference signal received power (RSRP), and predicted SSBs may be selected from the sorted list.

[0129] Based on the k optimal SSB beams determined, the WTRU may initiate initial access to the PRACH resource (e.g., by transmitting a PRACH preamble) (e.g., starting with the SSB beam at the top of the list of k optimal SSB beams). If the WTRU uses the PRACH preamble of the PRACH resource corresponding to the predicted SSB, the WTRU may receive, be provided with, and / or configure one or more informational configurations regarding one or more SSB-specific (e.g., beam-specific) parameters. The WTRU may receive configuration information as part of the initial access procedure (e.g., via RAR, Msg4, and / or MsgB). For example, SSB beam-specific parameters are information about the paising search space of the predicted SSB, and the WTRU may receive and index a list or table showing the corresponding time, frequency resources. In one example, the gNB may decide to transmit a configuration for the WTRU if it can determine that the WTRU predicted the predicted SSB based on the received PRACH, since the corresponding SSB was not transmitted in the first place.

[0130] In one embodiment, a PRACH preamble may be transmitted in an AIML scenario with skipped SSBs. In one example, the WTRU may perform one or more of the following: The WTRU may consist of a set of transmitted SSB beams and a set of predicted SSB beams. The WTRU may select the predicted beams to perform initial access on (e.g., based on predicted RSRP).

[0131] A WTRU may initiate initial access by transmitting or sending a PRACH or random access preamble on or using a PRACH resource or random access resource, the PRACH resource may be selected based on one or more of the relevant detected SSB beams, predicted SSB beams, and / or combinations of multiple detected and / or predicted SSB beams.

[0132] In one example, a PRACH resource may be selected based on the relevant detected SSB beam. For example, a WTRU may be configured to send a random access preamble or a PRACH preamble on a resource corresponding to the relevant detected SSB beam or the SSB actually transmitted. The WTRU may indicate a preferred predicted beam to the gNB as a function of PRACH preamble selection or Msg3 transmission, or in transmissions performed after the RA procedure. Instructions sent in random access message 3 may indicate skipped SSBs. For example, the gNB may indicate whether the predicted beam is acceptable (e.g., by sending the same RAPID(preamble ID) or by sending a different ID to instruct the WTRU to select a different beam (e.g., a detected beam or a predicted beam)).

[0133] For example, in terms of the gNB implementation (e.g., if the gNB turns off those beams to reduce power consumption), it may be beneficial if the gNB does not transmit SSB. The gNB may also not want to receive anything on those beams. Unless requested by the WTRU, the gNB may not use those beams.

[0134] In one example, a PRACH resource may be selected based on the predicted SSB beam. For instance, a WTRU may be configured to transmit a PRACH preamble on a resource corresponding to one of the predicted SSB beams (e.g., the one with the highest RSRP). A random access preamble or random access resource may indicate a skipped SSB. A WTRU may be configured or determined to use one or more random access parameters (e.g., for PRACH transmission and RAR reception, e.g., the number of PRACH preamble retransmissions, power ramp-up value, etc.).

[0135] In one example, a PRACH resource may be selected based on a combination of detected and / or predicted SSB beams. For example, a WTRU may be configured to transmit PRACH preambles on multiple resources corresponding to the detection and / or prediction of multiple SSB beams (e.g., based on the configuration received for a detected SSB (e.g., in the direction of the detected SSB)) (e.g., a first resource may indicate that both the detected SSB and a first predicted SSB beam are preferred beams, a second resource may indicate that the detected SSB and a second predicted SSB beam are preferred beams, and so on). For example, if a gNB receives a PRACH on a resource corresponding to an SSB beam that was not actually transmitted, the gNB may consider that the SSB beam was selected based on prediction.

[0136] The WTRU may monitor the PDCCH scrambled with RA-RNTI to detect the RAR within the RAR-Window period corresponding to the transmitted PRACH and / or associated detected and / or predicted SSB beams. In one example, if the WTRU receives a RAR or downlink transmission, the WTRU may continue with its initial access (e.g., sending Msg3). The WTRU may receive the downlink transmission using the beam associated with the skipped SSB.

[0137] In this specification, initial access and random access (RA) may be used interchangeably to refer to one or more procedures related to establishing connectivity between the WTRU and the network. Random access procedures may be triggered by events such as, for example, initial access from an RRC idle state, RRC connectivity re-establishment procedures, DL or UL data arrival during RRC_CONNECTED when the UL synchronization state is "asynchronous", UL data arrival during RRC_CONNECTED when the PUCCH resource for scheduling requests (SR) is unavailable, SR failure, requests by the RRC during synchronization reconfiguration (e.g., handover), RRC connectivity reactivation procedures from RRC_INACTIVE, establishment of secondary TAG time adjustments, beam failure recovery, and / or consistent UL LBT failures in the SpCell.

[0138] WTRU can be configured to perform one or more types of initial access (e.g., CBRA with 4-stage RA, CBRA with 2-stage RA, CFRA with 4-stage RA, and / or CFRA with 2-stage RA).

[0139] In one embodiment, random access resources may be used. The WTRU may receive, identify, or set time-domain resource allocations for consecutive random access opportunities (ROs) based on the higher-level parameter prach-ConfigurationIndex, or msgA-PRACH-ConfigurationIndex if set. These parameters may indicate PRACH configuration indexes corresponding to tables containing random access parameters.

[0140] In one example, one or more of the following parameters may be derived from the table. For example, the preamble format may refer to any of the possible formats, i.e., A1, A2, A3, B1, A1 / B1, A2 / B2, A3 / B3, B4, C0, C2. The preamble format may identify the corresponding cyclic prefix code (CP) period, sequence sub-period, and guard time period (if applicable). The frame number and slot number may indicate the frame that can be used for PRACH transmission and the corresponding PRACH slot within that frame. The start symbol may determine the symbol level index corresponding to the start position of the first RO transmission within the PRACH slot. The number of PRACH slots within a 60kHz slot may define the number of PRACH slots within a reference PRACH slot (for example, at high SCS such as 120kHz, 480kHz, and 960kHz, the 60kHz PRACH slot is considered the reference slot). The number of PRACH occurrences in the time domain within a PRACH slot (NtRA,slot) can define the number of consecutive ROs located within the PRACH slot in the time domain. The duration of a PRACH can correspond to a preamble format that suggests the number of sequence parts within an RO.

[0141] The WTRU may receive frequency-domain resource allocations for ROs based on msg1-FrequencyStart or msgA-RO-FrequencyStart, and / or one or more of the higher-level parameters msg1-FDM or msgA-RO-FDM. msg1-FrequencyStart or msgA-RO-FrequencyStart (if set) may indicate the offset that the lowest PRACH transmit opportunity in the frequency domain has relative to PRB 0. msg1-FDM or msgA-RO-FDM (if set) may indicate the number of PRACH transmit opportunities frequency-divided (FDMed) within a single time-domain RO. For example, the WTRU may receive, identify, or set the number of ROs (M) in the frequency domain per time-domain PRACH opportunity based on higher-level parameters msg1-FDM, msg1-FDM-16, or msgA-RO-FDM (if set), msg1-FDM={1,2,4,8}. For example, WTRU may number PRACH frequency resources in ascending order from the lowest frequency as nRA={0,1,…,M-1} in the initial uplink BWP during initial access, and in the active uplink BWP otherwise.

[0142] The WTRU can receive the association and mapping between SS / PBCH block indices and PRACH transmission opportunities based on the upper-layer parameter ssb-perRACH-OccasionAndCB-PreamblesPerSSB={1 / 8,1 / 4,1 / 2,1,2,4,8,16}. This parameter may indicate the number of preambles per SS / PBCH block index per PRACH transmission opportunity, as well as the number of SS / PBCH block indices associated with each PRACH transmission opportunity. The WTRU can then perform PRACH transmissions on each random access resource according to the spatial relationship with the associated SS / PBCH blocks.

[0143] In exemplary embodiments, competition-based and / or competition-free PRACH preambles may be used. In one example, the same set of preambles as described above may be set for each SSB, so that multiple WTRUs can access the same preamble, and the initial access procedure is the same as in the competition-based scenario. In one example, these preambles may refer to a legacy preamble that carries information about the SSB beams selected by the WTRUs (detected, skipped, and / or predicted SSBs). In one example, these preambles may carry additional information implicitly or explicitly as described above. If multiple WTRUs select the same preamble, the WTRUs may receive instructions from the network (e.g., in RAR messages, Msg4, MsgB) indicating whether the preamble is occupied or whether they should select a different preamble. In the response from the network (e.g., in Msg4 or MsgB), the WTRU may interpret the failure to receive a preamble ID within a pre-configured time frame as an indication that the preamble has been occupied by another WTRU. The WTRU may then select a different preamble in a similar manner to a conflict-based initial access. If conflict resolution is unsuccessful after retransmitting Msg3, the WTRU may revert to sending Msg1. If no conflict occurs, the WTRU may receive a response from the network (in RAR, Msg4, or MsgB) confirming that the preamble has been accepted (e.g., receipt of the same Random Access Preamble ID (RAPID)). The WTRU may then send Msg3 using the UL grant scheduled in the response.

[0144] In one example, a preamble may be a dedicated preamble designated by the network in a non-conflicting manner. For instance, one or more preambles may be “reserved” by the network for a WTRU or a group of WTRUs. Conflict-free preambles may correspond to the same or different resources (e.g., RACH opportunities in the time domain, PRACH opportunities in the frequency domain, or SSBs corresponding to one or more beams in the spatial domain) as conflict-based preambles. These preambles may correspond to transmitted SSBs, skipped SSBs, or predicted SSBs.

[0145] In the two-stage initial access procedure, the MsgA may include a conflict-free preamble on PRACH and a payload on PUSCH. After sending the MsgA, the WTRU may monitor for a response from the network within a pre-configured time frame. In this case as well, the PRACH preamble used by the WTRU may correspond to the transmitted / associated or expected SSB. A dedicated preamble and PUSCH resources are configured for sending the MsgA, and upon receiving a network response, the WTRU terminates the initial access procedure.

[0146] In the embodiment, a PRACH resource may be selected for a predicted beam. The WTRU may detect a first SSB beam (e.g., during initial access). The WTRU may predict and / or determine one or more predicted SSBs from a list of skipped SSB beams that are not transmitted or preferred predicted SSBs (e.g., based on the AIML system). The WTRU may select the optimal predicted SSB and initiate the initial access procedure accordingly (e.g., PRACH preamble transmission).

[0147] In one example (for instance, alternatively), the WTRU may be composed of information about the relationships between two or more SSB beams (for example, by a network), such that the WTRU receives a mapping table from the network showing the relationships between two or more transmitted and / or skipped SSB beams based on spatial correlation (e.g., approaching or adjacent beams) or beam parameters (e.g., two beams at a particular elevation angle, or two beams with RSRP exceeding a threshold are associated).

[0148] In one example, the associations between one or more transmitted and / or skipped SSBs may be configured by the network and shown in the WTRU in terms of beam index. For example, this association may apply to one or more cases. For instance, the WTRU may be configured to apply the association if one or more conditions are met (e.g., use the association at the cell edge and use the (e.g., legacy) detection beam otherwise).

[0149] The WTRU may determine the PRACH resources for transmitting the selected, configured, and / or determined PRACH preamble. One or more of the following may be applied: PRACH resources for detected SSBs based on detected SSB beams, PRACH resources for predicted SSBs based on the associated detected SSB beams, PRACH resources for predicted SSBs based on the predicted SSB beams, and / or PRACH resources based on a combination of multiple detected SSB beams and / or predicted SSB beams.

[0150] During initial access (for example, when a WTRU performs initial access for the first time when joining a new cell, or when a WTRU performs initial access after a long period of inactivity), the WTRU may select PRACH resources based on detected SSB beams. During a session, the WTRU may receive configurations (e.g., from a gNB) to use relevant detected and / or predicted SSB beams, thereby allowing the WTRU to select PRACH resources based on relevant detected or predicted SSB beams during future initial accesses.

[0151] In one embodiment, the WTRU may be configured to determine or perform a PRACH preamble transmission based on the PRACH resource corresponding to the relevant detected SSB beam. Based on the WTRU's selection of the PRACH preamble, the WTRU may indicate a preferred predicted SSB beam (e.g., for a gNB). For example, if the WTRU predicts the best predicted beam as a first (e.g., relevant and / or candidate) skip beam, the WTRU may select and transmit a PRACH preamble from the first set of preambles; if the WTRU predicts the best predicted beam as a second (e.g., relevant and / or candidate) skip beam, the WTRU may select and transmit a PRACH preamble from the second set of preambles, and so on. As an example (e.g., alternatively), the WTRU may indicate a preferred predicted SSB beam (e.g., for a gNB) as part of an initial access signal (e.g., Msg3 and / or MsgB transmission). The WTRU (for example, otherwise) switches to connected mode and, after connecting to the gNB, may indicate the preferred predicted SSB beam (for example, to the gNB).

[0152] Sending a PRACH preamble on the resource corresponding to the detected SSB may be useful if the gNB implementation does not transmit an SSB. For example, a gNB may turn off some beams to reduce power consumption. The gNB may not want to receive preambles corresponding to these beams or data transmissions through these beams. Beams may not be activated unless specifically requested by the WTRU (e.g., by selecting and transmitting a preamble corresponding to a preferred predicted beam). Even with a request from the WTRU, the network may not activate a beam. For example, a gNB may decide not to activate a preferred predicted beam for the WTRU if it determines that an already activated (e.g., adjacent) SSB beam is sufficient to meet the WTRU's data transmission requirements. In such a case, the gNB may send instructions to the WTRU to select a corresponding SSB beam.

[0153] In this specification, the preamble and the PRACH preamble may be used interchangeably. In one embodiment, the WTRU may be configured to transmit one or more preambles for one or more associations of SSBs. For example, the WTRU may indicate selected, predicted, skipped, and / or detected SSBs (e.g., indices) based on the selection of PRACH preambles. For example, a first preamble may be used to indicate a first selected SSB (e.g., from a list of skipped SSBs and / or a list of transmitted SSBs, a list of predicted SSBs, etc.), a second preamble may be used to indicate a second selected SSB, and so on.

[0154] A preamble can be a long-sequence preamble or a short-sequence preamble. A preamble can be a legacy preamble or a new preamble. In a new preamble, additional bits may be added, for example, to convey additional information. The preamble format chosen by the WTRU may depend on the scenario and / or the additional information that the WTRU wants to convey (e.g., to the network). For example, in cell deployment, some preamble formats may be used for large cells, while others may be used for small cells or macrocells. For example, in frequency band deployment, some preamble formats may be used in FR1 deployment, while others may be used in FR2 deployment. In subcarrier interval deployment, for example, a first preamble format may be used for a first subcarrier interval (e.g., 15 or 30 kHz), and a second preamble format may be used for a second subcarrier interval (e.g., 60 or 120 kHz). For example, in the case of information specific to AI / ML beam management, the WTRU may use a first preamble for a first detected SSB, a second preamble for an SSB predicted based on a first skipped associated SSB, a third preamble for an SSB predicted based on a second skipped associated SSB, and so on.

[0155] The WTRU may use the selected preamble to indicate the SSB selected and / or preferred by the WTRU (for example, to the network). In one example, the WTRU may implicitly indicate additional information based on the selection of the PRACH preamble. For example, the WTRU may decide or configure to use a first set of preambles for a first operating mode, a second set of preambles for a second operating mode, and so on. For example, the WTRU may select a first preamble for a first SSB and indicate that the WTRU's AI / ML model is using a first type, size, etc. of the SetB beam for beam prediction; the WTRU may select a second preamble for a first SSB and indicate that the WTRU's AI / ML model is using a second type, size, etc. of the SetB beam for beam prediction, and so on. For example, a WTRU might select a first preamble for a first SSB to indicate that the WTRU is using a first type of AI / ML model (e.g., a recurrent neural network (RNN)), a WTRU might select a second preamble for the first SSB to indicate that the WTRU is using a second type of AI / ML model (e.g., a deep neural network (DNN)), and so on. As an example, additional bits may be added to the preamble to convey and / or indicate additional information. In yet another example, additional information may be encoded in the preamble (e.g., through scrambling).

[0156] In one example, an AI / ML-enabled WTRU may predict the optimal beam at a future point in time (e.g., the beam with the highest predicted RSRP) based on past beam IDs and their corresponding RSRPs, beam angles, and associated beam parameters. The WTRU may be configured to transmit a PRACH preamble on a resource corresponding to one of the predicted SSB beams (e.g., the one with the highest predicted RSRP based on the output of the AI / ML model).

[0157] In one example, a WTRU may receive configuration information in an SIB (e.g., an existing SIB or an AI / ML-specific SIB) regarding how to generate a preamble corresponding to a predicted beam. For example, a WTRU may be allocated space (e.g., an ID space) by the network and generate a preamble corresponding to a predicted SSB beam. If a gNB receives a PRACH on a resource corresponding to an SSB beam that was not actually transmitted, the gNB may assume that the SSB can be selected, predicted, and / or determined based on the prediction.

[0158] In one example, a WTRU may be able to use the same preamble currently associated with a beam at a future moment in time. For instance, a WTRU may perform an initial access using a beam detected / transmitted at time T1 (e.g., beam X) and transition to a connected state. The WTRU may then transition to an idle state at time T2. At time T3, the WTRU may decide to perform an initial access at the subsequent time T4 based on the predicted beam. If the WTRU remains stationary, the AI / ML model may determine that the same beam X is the most suitable beam to use for the initial access. As a result, the WTRU may be able to use the same preamble that it previously used to perform the initial access.

[0159] In one embodiment, a WTRU transmitting a PRACH preamble on a PRACH resource based on a predicted SSB beam may be configured to use, or determined to use, one or more different random access parameters compared to (legacy) PRACH preamble transmission on a resource based on a detected SSB. In one example, the WTRU may explicitly set random access parameter values. In one example, the WTRU may receive differential values ​​and / or offsets applied to parameters set for (legacy) PRACH preamble transmission on a resource based on a detected SSB. For example, the number of PRACH preamble retransmissions, power ramp-up value, random access response time window, etc., on a PRACH resource based on a predicted SSB beam may differ from those of (legacy) PRACH preamble transmission on a resource based on a detected SSB.

[0160] For example, if a WTRU is configured to perform initial access using predicted SSBs, the RACH resources, configurations, and / or parameters associated with one or more predicted SSB beams may be configured to remain valid for a longer period of time. These RACH resources and / or configurations may include any of the preambles, sequences, partitions, time, and / or frequency resources associated with RACH. RACH resources may also include RACH opportunities that the WTRU can use when transmitting a RACH preamble. Parameters associated with RACH resources may include start / end times, transmit time, periodicity, transmit power, transmit spatial direction, etc. RACH resources may be selected by the WTRU from a set that is, for example, common to multiple UEs or exclusive to the WTRU. Common or exclusive RACH resources may be accessed through broadcast channels / beams (e.g., SIB, SSB), initial access messages (e.g., in Msg2 or MsgB), or (pre)configuration within the WTRU.

[0161] In one embodiment, the WTRU may be configured to transmit a PRACH preamble over multiple resources corresponding to the detection and / or prediction of multiple SSB beams. For example, the WTRU may use (combined) PRACH resources to indicate that a predicted SSB (e.g., the one with the highest measured and / or predicted RSRP) is preferred over a detected SSB. For PRACH transmission, the WTRU may use spatial filters and / or beam directions corresponding to the detected SSB and / or QCL'd. For example, the WTRU may use a first (combined) PRACH resource set to indicate that a detected SSB beam and a first predicted (and / or skipped) SSB beam are preferred beams, a second (combined) PRACH resource set to indicate that a detected SSB beam and a second predicted (and / or skipped) SSB beam are preferred beams, and so on.

[0162] The network may determine the optimal SSB beam to use for the WTRU to grant initial access, based on factors such as loading and beam quality (e.g., RSRP). The network may indicate the selected beam using its corresponding preamble ID (RAPID) (e.g., within a RAR message). After sending a PRACH preamble over a PRACH resource, the WTRU may monitor the downlink control channel (e.g., CORESET, PDCCH, etc.) corresponding to each corresponding preferred SSB (e.g., detected SSB and first predicted SSB, detected SSB and second predicted SSB, etc.). In one example, the WTRU may detect one or more RAR messages (e.g., RAR PDCCH), and the WTRU may determine the corresponding SSB based on the RAPID received within the RAR message. One or more of the solutions described above for initial access based on detected or predicted beams may also apply to this case.

[0163] After transmitting a PRACH preamble on a detected, skipped, and / or predicted beam, the WTRU may monitor the PDCCH scrambled with RA-RNTI to detect the RAR within the RAR-Window period corresponding to the transmitted PRACH and / or associated detected and / or predicted SSB beam. If the WTRU receives the RAR (in Msg2 / MsgB), it may also receive the UL grant contained in the RAR, which it may use to send an RRC setup request (e.g., Msg3). The network may estimate the timing (e.g., propagation delay) based on the received preamble (e.g., Msg1 / MsgA) and send the TA value to the WTRU within the RAR message. In response to Msg3, the WTRU may receive an RRC setup complete message (e.g., Msg4), which, if successful, may transition to a connected state. In one embodiment, if the PRACH preamble transmission based on the predicted SSB beam fails (for example, if no RAR is received within the RAR window period), the WTRU may determine a fallback procedure.

[0164] The WTRU may exhibit specific behaviors if a PRACH transmission fails. In one embodiment, the WTRU may perform one or more of the following: The WTRU may consist of a set of transmitted SSB beams and a set of predicted SSB beams. The WTRU may select a predicted beam (e.g., based on a predicted RSRP) to perform an initial access (e.g., a PRACH preamble transmission). The WTRU may monitor the PDCCH scrambled with RA-RNTI within a period RAR-Window corresponding to the transmitted PRACH and / or associated detected and / or predicted SSB beams, and detect RARs. If the WTRU receives an RAR, it may continue with an initial access (e.g., sending Msg3). If no RAR is received within a set time frame or based on a counter, the WTRU may perform one or more of the following exemplary methods: In one example, the WTRU may switch to another SSB beam from the predicted SSB beam list, sequentially up to a maximum of k beams (e.g., selected in descending order of RSRP). The predicted set of SSBs is sorted in descending order of reference signal received power (RSRP), and a predicted SSB may be selected from the sorted list. In one exemplary method, the WTRU may transmit a PRACH for the detected beam. In one exemplary method, the WTRU may wait for a legacy SSB burst with each SSB beam transmission. For example, the gNB transmits an SSB burst with each intended SSB beam (ssb-SetA) transmission, but the intervals between them may be longer. For example, after M SSB bursts, including skipped SSB beams, the gNB may transmit an SSB burst with each intended beam transmission. After waiting for up to M SSB bursts (e.g., M is set in MIB or SIB1), the WTRU may find the optimal SSB beam accordingly. In one exemplary method, the WTRU may reject this cell and attempt to find a different SSB block in a different synchronous raster or another cell.

[0165] A WTRU may consist of a set of transmitted SSB beams and a set of predicted SSB beams. In one or more exemplary embodiments of this specification, the transmitted SSB beams may be associated with SetB or its configuration. In one exemplary embodiment, a WTRU may be configured to predict the RSRP of a first beam (e.g., a predicted beam) based on the measured RSRP of a second beam (e.g., a transmitted beam). The terms predicted beam and skipped beam may be used interchangeably. The terms transmitted beam, SetB beam and measured beam may be used interchangeably. The term beam may refer to an SSB beam, a CSI-RS beam, or both.

[0166] In one exemplary embodiment, the WTRU may consist of parameters for a random access procedure corresponding to a skipped beam, and one or more parameters may be configured specifically for preamble transmissions associated with a predicted beam. For example, the WTRU may consist of the maximum number of random access preamble transmissions associated with each predicted beam and / or set for each predicted beam. Different values ​​may be set for the maximum number of retransmissions for predicted beams and detected beams. Different values ​​may be set for the ra-ResponseWindow for predicted beams and detected beams.

[0167] In one embodiment, an RA preamble transmission associated with a skipped SSB may be performed. The WTRU may be configured to predict one or more parameters (e.g., RSRP) of one or more SSB beams (e.g., predicted SSB beams) based on one or more parameters (e.g., RSRP) of one or more measured SSB beams (e.g., transmitted SSB beams). The WTRU may be configured to select the optimal beam for preamble transmission, which may be the predicted beam or the detected beam. In the first solution, if the difference between one or more predicted parameters and one or more measured parameters (e.g., RSRP) is greater than a (pre-set) threshold, the WTRU may select the detected beam for PRACH preamble transmission. Otherwise, the WTRU may select the predicted beam for PRACH preamble transmission. The WTRU may determine the parameters to apply to the random access procedure based on the beam type, where the beam type may refer to the transmitted SSB beam, the predicted SSB beam, etc.

[0168] In one exemplary embodiment, the WTRU may consist of a first ra-ResponseWindow (e.g., Random Access Response Time Window) value and a second ra-ResponseWindow value. The WTRU may apply the first ra-ResponseWindow value if the preamble transmission is associated with a detected SSB beam. The WTRU may apply the second ra-ResponseWindow value if the preamble transmission is associated with a predicted SSB beam. The WTRU may consist of different retransmission count sets and power ramping parameters based on the type of beam selected for the random access procedure. After the preamble transmission, the WTRU may monitor the PDCCH scrambled with RA-RNTI within the ra-ResponseWindow corresponding to the transmitted PRACH and / or associated detected and / or predicted SSB beams to detect a RAR. If the WTRU receives a RAR, it may continue with the initial access (e.g., transmission of Msg3).

[0169] If preamble transmission in a predicted beam fails, the WTRU may exhibit specific behavior. In one exemplary embodiment, the WTRU may be configured to handle preamble transmission failures depending on the type of beam associated with the preamble transmission. Hereinafter, the beam type may refer to the transmission state of the beam (e.g., transmitted and / or measured beam, untransmitted (e.g., predicted beam)). For example, in the transmission of a preamble associated with a predicted beam, if the WTRU does not receive a Random Access Response (RAR) before the ra-ResponseWindow expires, the WTRU may consider the RAR reception to have been unsuccessful (e.g., a failure of the RAR associated with the predicted beam). In one exemplary embodiment, the WTRU may be configured to maintain a preamble transmission counter dedicated to preamble transmissions associated with a predicted beam or predicted SSB. In one exemplary embodiment, the WTRU may be configured to increment a counter associated with a predicted beam if the RAR reception fails.

[0170] The WTRU may exhibit specific behaviors based on the predicted beam-specific maximum transmit power. Upon a RAR failure associated with a predicted beam, the WTRU may be configured to perform a preamble retransmission on that predicted beam. The WTRU may be configured to perform retransmissions on the same predicted beam up to a maximum number of retransmissions. In one exemplary embodiment, the maximum number of retransmissions may be set individually for each predicted beam. In one example, the maximum number of retransmissions may be set to be greater than or equal to 1. If the maximum number of retransmissions is reached for a particular predicted beam, the WTRU may be configured to switch to the next best predicted beam. For example, the next best predicted beam may be determined based on descending RSRP. A set of predicted SSBs may be sorted in descending order of Reference Signal Received Power (RSRP), and a predicted SSB may be selected from the sorted list. In one exemplary embodiment, if the maximum number of retransmissions is reached for a particular predicted beam, the WTRU may be configured to switch to the next best detected beam. In one exemplary embodiment, when the maximum number of retransmissions for a particular predicted beam is reached, the WTRU may be configured to switch to the next optimal beam, regardless of whether that beam is a predicted beam or a measured beam.

[0171] The WTRU may exhibit specific behavior based on the cumulative maximum number of retransmissions across all predicted beams. In one exemplary embodiment, the WTRU may consist of a first maximum number of retransmissions and a second maximum number of retransmissions, the first maximum number of retransmissions may be associated with each predicted beam, and the second maximum number of retransmissions may be associated with the cumulative number of retransmission attempts across each predicted beam. The first maximum retransmission value may be less than or equal to the second maximum retransmission value. In one exemplary embodiment, when the second maximum retransmission value is reached, the WTRU may be configured to switch to the next best detected beam. In one exemplary embodiment, the WTRU may be configured to switch the maximum number of predicted beams during a random access procedure. The maximum number of predicted beams may be preset as specified herein. When the maximum number of predicted beams is reached, the WTRU may be configured to switch to the next detected beam. In one exemplary embodiment, the WTRU may consist of a maximum number of retransmissions across a plurality of (e.g., each) predicted beams.

[0172] In one embodiment, the WTRU may determine beam-specific retransmissions based on confidence levels. The WTRU may be configured with (pre-set) rules for determining the maximum number of retransmissions for each predicted beam. For example, given the maximum number of retransmissions across each predicted beam, the WTRU may determine the maximum number of retransmission attempts for each predicted beam based on the confidence level of the prediction. For example, the WTRU may retransmit N1 times for a first predicted beam with confidence level C1 and N2 times for a second beam with confidence level C2, where N1 > N2 if C1 > C2.

[0173] The WTRU may wait for a legacy SSB burst in which all SSB beams are transmitted. In one exemplary embodiment, if the number of RAR failures associated with a predicted beam exceeds a preset number, the WTRU may be configured to perform a random access procedure based on a legacy SSB burst in which each SSB beam is transmitted. Here, a RAR failure may be triggered based on one or more conditions, such as exceeding the maximum number of retransmissions associated with a predicted beam, exceeding the maximum cumulative retransmission value associated with each predicted beam, or exceeding the maximum number of retransmissions for a predicted beam. The WTRU may be configured to interrupt the ongoing random access procedure and wait for a legacy SSB burst transmission. For example, the WTRU may be configured for legacy SSB beams via the ssb-PositionsInBurst setting (e.g., within SIB1). The WTRU may be configured with a longer periodicity for legacy SSB beams and a shorter periodicity for SSB bursts with SetB beams. For example, after M SSB bursts with skipped SSB beams, the WTRU may be configured to receive SSB bursts using the legacy SSB beam. The WTRU may be configured with a value of M based on MIB or SIB1, and for example, in the event of a RAR failure related to a predicted beam, the WTRU may be configured to perform a random access procedure based on the reception of the legacy SSB beam.

[0174] The WTRU may reject a cell and trigger initial access to another cell. In one exemplary embodiment, if the number of RAR failures associated with a predicted beam exceeds a preset number, the WTRU may be configured to perform one or more of the following actions: For example, the WTRU may abort an ongoing random access procedure. The WTRU may notify higher layers of the random access problem. Based on the determination that the RAR was not successfully received during the random access response window and that the number of retransmissions for the first or second predicted SSB has exceeded the maximum number of retransmissions, the WTRU may be configured to further notify higher layers of the random access problem. The WTRU may prohibit initial access to this cell for a preset time (e.g., until a preset timer has elapsed). The WTRU may trigger initial access to a different cell (e.g., the WTRU may attempt to detect an SSB block in a cell such as the same frequency (within the frequency) or a different frequency (between frequencies), or a different synchronous raster).

[0175] In an embodiment, correction and verification procedures may be performed on the predicted beam based on the received RAR. In this embodiment, the terms “skipped SSB” and “beam not actually transmitted” are used interchangeably. In an exemplary embodiment, the WTRU may perform one or more of the following: The WTRU may determine or select the predicted SSB beam as the optimal beam (e.g., based on the predicted RSRP) based on the detected and / or received SSB beam and the AIML model. The detected SSB beam is the actually transmitted SSB, and the predicted SSB beam is the SSB not currently transmitted by the base station. The WTRU has received instructions for both the actually transmitted SSB and the predicted SSB. The WTRU may initiate an initial access procedure by transmitting a PRACH preamble for the predicted SSB beam (e.g., within the time and frequency resource associated with the predicted SSB beam) or by transmitting a random access preamble using a random access resource. The random access preamble or random access resource is associated with the predicted SSB. The WTRU may monitor to receive RAR within the RAR window. After receiving the RAR (e.g., RAR PDCCH and / or RAR PDSCH on the predicted SSB beam and the QCL beam), the WTRU may measure the RSRP (e.g., based on the reference signal in the RAR message (e.g., DMRS)). The RAR may be received via the beam associated with the predicted SSB. The measured RSRP may be associated with the received RAR. The WTRU may compare the measured RSRP based on the received RAR with the predicted RSRP of the predicted SSB, or calculate the difference between the predicted RSRP of the predicted SSB and the measured RSRP of the predicted SSB. The predicted SSB is based on the predicted RSRP of the predicted SSB.The WTRU may be configured or received (e.g., via MIB, SIB1, and / or RAR) one or more parameters relating to an offset and / or threshold for comparing the RSRP measured based on RAR (e.g., PDCCH DMRS or PDSCH DMRS) with the RSRP predicted for SSB. For example, the RSRP measured from SSB and DMRS may differ. Also, there may be a (e.g., large) difference in the transmit power between SSB and DMRS. Therefore, the gNB may provide an offset / threshold (e.g., 10 dB) for comparing the values. Based on the comparison result and one or more offsets or thresholds, the WTRU may verify the accuracy of the prediction (e.g., determine whether the difference between the predicted RSRP and the measured RSRP is less than the threshold (e.g., 10 dB)). If the difference between the predicted RSRP and the measured RSRP is below a (pre-set) threshold, the WTRU may determine that the predicted beam is sufficiently accurate and continue using the predicted beam for the transmission of further signals (e.g., Msg3) by sending an instruction requesting that the beam associated with the predicted SSB continue to be used in subsequent communications. If the difference between the predicted RSRP and the measured RSRP is greater than a (pre-set) threshold, the WTRU may determine that the predicted beam is not sufficiently accurate. The WTRU may reject the predicted beam and continue selecting another beam, or, following the procedures considered for failed PRACH transmissions, select a new predicted SSB and perform a new initial access procedure associated with the beam corresponding to the new predicted SSB. In one example (e.g., alternatively), if the WTRU transmits a PRACH based on multiple (e.g., two) combinations of detected and / or predicted SSB beams, the WTRU may receive multiple (e.g., two) RAR messages for the corresponding beams. The WTRU may measure the RSRP of each received RAR message and determine the optimal beam (e.g., the one with the higher RSRP). The WTRU may transmit additional signals (e.g., Msg3) based on the selected optimal beam.

[0176] The WTRU may detect one or more SS / PBCH blocks (SSBs) from one or more cells (e.g., during initial access, cell search, and / or cell (re)selection), where the cells may be candidate cells used for initial access and / or cell (re)selection. From at least one of the detected cells and / or candidate cells, the WTRU may determine, indicate, and / or select at least one of the detected SSBs as the optimal SSB (e.g., the one with the highest measured and / or calculated received power (e.g., RSRP) and the lowest measured and / or calculated interference). In one example, the WTRU may detect, decode, and receive one or more informational parameters (e.g., via MIB or SIB1) regarding whether skipped SSBs are valid in the detected cells. In one example, the WTRU may receive one or more informational parameters regarding a list of SetA of planned SSBs (e.g., ssb-SetA), a list of transmitted SSBs (e.g., ssb-SetA), and / or a list of skipped or not transmitted SSBs.

[0177] In one example, a WTRU may configure or determine a first type of SSB beam (e.g., a transmitted SSB beam), a second type of SSB beam (e.g., a predicted SSB beam), and so on. A WTRU may detect one or more transmitted SSB beams and measure their beam quality (e.g., RSRP). Using the measured beam quality of the detected transmitted SSB beams, a WTRU may predict the beam quality of a predicted SSB beam (e.g., predicted RSRP) (e.g., using an AI / ML model). A WTRU may use different types of SSB beams (transmitted, predicted, etc.) to perform initial access, cell (re)selection, etc. For example, a WTRU may select one or more SSB beams in initial access based on beam quality (e.g., the beam with the highest RSRP). A WTRU may utilize the measured beam quality (e.g., RSRP) of the received SSB beams and / or the predicted beam quality (e.g., predicted RSRP) of the predicted SSB beams.

[0178] In one example, the WTRU may decide to send a PRACH preamble to a detected cell, in which case the WTRU may determine the time and frequency resources for sending the PRACH in relation to the predicted SSB beam. After sending the PRACH preamble, the WTRU may monitor and attempt to detect Random Access Response (RAR) messages (e.g., DCI with CRC scrambled in RA-RNTI) within the RAR window or time limit. In one example, if the WTRU decides to use a four-step Random Access (RA) procedure, the WTRU may send configured, selected, and / or determined PRACH preambles to the cell. After sending the PRACH preamble, the WTRU may monitor DL ​​messages (e.g., PDCCH and / or PDSCH) that provide UL grants (e.g., those indicating RAR messages). The WTRU may send UL messages or instructions (e.g., within PUSCH) based on the UL grants. In one example, if the WTRU decides to use a two-stage RA, the WTRU may send a MsgA containing the configured, selected, and / or determined PRACH preambles, and a PUSCH to transmit the message to the cell. After sending the MsgA, the WTRU may monitor for a DL message (e.g., PDCCH) (e.g., indicating a MsgB), which may contain (e.g., at least) RAR and may contain conflict resolution information.

[0179] A WTRU (e.g., an AIML-enabled UE) may select a cell to camp (e.g., as a suitable cell) (e.g., during initial access and / or cell (re)selection procedures). In one example, a WTRU may select a cell based on one or more measurement parameters (e.g., measured, evaluated, and / or predicted RSRP, RSRQ), cell ranking configuration, measured and / or evaluated interference, etc. A WTRU may select an SSB (e.g., an SSB beam) predicted as the optimal SSB within the cell. A WTRU may transmit a PRACH preamble to the selected cell associated with the selected predicted SSB. A WTRU may indicate a determined or selected active operating mode (e.g., AIML operation) through, for example, a PRACH transmission (e.g., AIML RO time, PRACH transmission over frequency resources, and / or use of a PRACH preamble selected from a first set indicating that the WTRU supports AIML, e.g., as described herein).

[0180] Beam quality parameters may be measured based on the received RAR message. In one exemplary embodiment, a WTRU (e.g., a WTRU that has transmitted a PRACH preamble based on a predicted SSB) may measure one or more beam quality parameters (e.g., RSRP, RSRQ, SINR, LOS probability, etc.) based on one or more reference signals received in the RAR message (e.g., the RAR is received via a QCL-enhanced beam with a selected predicted SSB beam). In one example, the WTRU may decide or set to compare the measured parameters with the corresponding predicted parameters. The WTRU may need to (re)evaluate the measured parameters for the purpose of scaling the parameters to make them comparable to the predicted parameters. The WTRU may receive, decide, provide, or (pre)set (e.g., via MIB, SIB, etc.) one or more scaling rules and / or parameters (e.g., offset values, scaling values, thresholds, etc.).

[0181] (Re)evaluation and / or scaling of measured parameters may be useful, for example, RSRP measured from SSB and DMRS may be expressed on different scales due to different frequency BWP and / or RS ranges in SSB and DMRS, different transmit powers in SSB and DMRS, etc. The WTRU may determine or use one or more scaling rules (e.g., adding, subtracting, multiplying, or dividing one or more scaling values) to make the values ​​comparable. One or more of RSRP, RSSI, RSRQ, SINR, LOS probability, and similar may be applied. For example, if RSRP, RSSI, or RSRQ is applied, the WTRU may receive one or more scaling rules and scaling parameters and perform addition, subtraction, multiplication, division, etc. on the corresponding measured parameters (e.g., received signal power, received signal strength, etc.). For example, when SINR is applied, the WTRU may receive one or more scaling rules and scaling parameters to perform addition, subtraction, multiplication, division, etc., on the measured SINR parameters (e.g., received signal power, received interference power, received signal strength, received interference strength, etc.). For example, when LOS probability is applied, the WTRU may receive one or more scaling rules to apply (e.g., addition, subtraction, multiplication, division) to the measured LOS probability for the received RS and RAR PDCCH and / or PDSCH signals.

[0182] Additional parameters may exist, including an offset between the beam quality (e.g., RSRP) estimated using the RAR-related RS and the SSB beam. For example, after receiving a RAR (e.g., a RAR PDCCH and / or RAR PDSCH on a QCL-covered beam with a selected predicted SSB beam), the WTRU may estimate the RSRP of the selected predicted SSB beam by measuring the beam RSRP of one or more RSs in the RAR message (e.g., DMRS of a RAR PDCCH and / or RSR PDSCH) and adding the offset configured or indicated by the gNB.

[0183] Verification of the accuracy of the prediction may be performed based on the RAR message. In one embodiment, the WTRU may determine and / or verify whether the prediction was accurate by comparing the measured parameters from the RAR with the predicted parameters for the predicted SSB, along with one or more offset values ​​and / or thresholds. The WTRU may receive, determine, provide, and / or (pre-)set one or more threshold values ​​(e.g., via MIB, SIB, etc.) to compare the measured parameters with the corresponding predicted parameters. In one example, the WTRU may determine that the difference between one or more of the predicted parameters and the corresponding (re)evaluated and / or scaled parameters based on the measured parameters from the RAR message (e.g., PDCC and / or PDSCH) is smaller than the corresponding threshold. The WTRU may determine that the accuracy level of the predicted SSB is acceptable and decide to proceed with the initial access procedure (e.g., sending Msg3).

[0184] For example (in other cases), the WTRU may determine that the difference between one or more predicted parameters and the corresponding (re)evaluated and / or scaled parameters based on measured parameters from RAR messages (e.g., PDCCH and / or PDSCH) is greater than the corresponding threshold. The WTRU may determine that the accuracy level of the predicted SSB is unacceptable. One or more of the following may apply: If the WTRU determines that the first predicted SSB beam may not meet the required accuracy, it may choose to use the second predicted SSB beam for the initial access procedure, the WTRU may perform the same procedure as in the case of a PRACH transmission failure, and / or the WTRU may continue the initial access procedure (e.g., by sending Msg3), and / or connect to the cell based on a beam that has the same spatial relationship as the predicted beam (e.g., the predicted beam and the QCL-connected beam).

[0185] In one example, if a WTRU determines that the first predicted SSB beam may not meet the required accuracy, it may choose to use the second predicted SSB beam for the initial access procedure. The WTRU may halt and / or reject any ongoing initial access based on the first predicted beam. The WTRU may initiate a new initial access procedure based on the second predicted beam. The WTRU may select the second predicted beam based on a list of k optimal predicted SSB beams (e.g., sorted in descending order of quality, such as RSRP, RSRQ, hypothetical BLER, etc.). Based on the determined second predicted SSB beam, the WTRU may initiate initial access on the PRACH resource corresponding to the second predicted SSB (e.g., PRACH preamble transmission). In one example, the WTRU may follow procedures considered in the event of a PRACH transmission failure. For example, the WTRU may follow procedures such as transmitting a PRACH preamble based on the detected beam, waiting for legacy SSB bursts when each SSB beam is transmitted, rejecting the current cell, attempting to detect another SSB block in a different synchronous raster or another cell, and / or similar procedures.

[0186] For example, a WTRU may perform conditional connections. For instance, a WTRU may continue the initial access procedure (e.g., via the transmission of Msg3) and / or connect to a cell based on a beam having the same spatial relationship as the predicted beam (e.g., the predicted beam and the QCLed beam). A WTRU may connect to a cell based on a beam having the same spatial relationship as the first predicted SSB in order to perform a new initial access procedure. A WTRU may indicate (e.g., via a flag indication) that the predicted beam (e.g., the one in use) is not the preferred beam (e.g., via a flag indication). A WTRU may indicate a preferred (e.g., predicted) beam via an indication (e.g., a beam index). A WTRU may indicate the first predicted SSB via a beam index in order to perform a new initial access procedure. A WTRU may transmit these indications as part of the initial access signal (e.g., Msg3) or as part of an indication signal (e.g., via UCI, MAC-CE, etc.) after connecting to a cell and switching from the initial access procedure to connected mode. After switching to connected mode, the WTRU may send a request to switch to the preferred beam or the first predicted SSB, or the WTRU may receive a request to switch to another beam (from a gNB, for example).

[0187] A comparison of prediction accuracy can be performed based on at least two RAR messages. In one embodiment, a WTRU may receive one or more RAR messages, and the WTRU may compare one or more measurement parameters for the received RAR messages to determine the accuracy of the predicted beam, and / or determine, select, and / or indicate the optimal beam accordingly. In one example, a WTRU indicating multiple preferred SSB beams (including, for example, SSB beams detected and / or predicted via a set of (combined) PRACH resources described herein (see Section 4.4 or Solution #1)) may receive multiple RAR messages within the RAR reception window. In one example, the WTRU may receive a first RAR signaling (e.g., RAR PDCCH and / or RAR PDSCH) corresponding to a first detected SSB, the WTRU may receive a second RAR signaling (e.g., RAR PDCCH and / or RAR PDSCH) corresponding to a first predicted SSB, and so on. In one example, the WTRU may determine the corresponding SSB based on the Random Access Preamble ID (RAPID) detected from the received RAR message.

[0188] The WTRU may measure a first set of one or more beam quality parameters (e.g., RSRP, RSRQ, SINR, LOS probability, etc.) based on one or more reference signals received in a first RAR signaling (e.g., a first detected SSB and RAR received via beam QCLed RAR) (e.g., via RAR PDCCH DMRS, RAR PDSCH DMRS, etc.), and the WTRU may measure a second set of one or more beam quality parameters (e.g., RSRP, RSRQ, SINR, LOS probability, etc.) based on one or more reference signals received in a second RAR signaling (e.g., a first predicted SSB and RAR received via beam QCLed RAR) (e.g., via RAR PDCCH DMRS, RAR PDSCH DMRS, etc.), and so on.

[0189] In one embodiment, the WTRU may compare one or more measured sets of parameters (e.g., a first set, a second set, etc.). The WTRU may determine the optimal beam based on a beam having optimal beam quality parameters (e.g., RSRP, RSRQ, LOS probability above a corresponding threshold, and / or theoretical BLER below a corresponding threshold, etc.). The WTRU may use the selected optimal beam for further initial access procedures (e.g., Msg3 transmission). In one embodiment (e.g., alternatively), the WTRU may compare one or more measured sets of parameters (e.g., a first set, a second set, etc.) with predicted parameters for a predicted beam (e.g., RSRP, RSRQ, LOS probability, etc.) or one or more predicted SSBs. To make a comparison, the WTRU may receive, determine, provide, or (pre-)set (e.g., via MIB, SIB, etc.) one or more parameters or configuration parameters, offset values, scaling rules, and / or scaling values, and may (re)evaluate and / or scale the one or more measured sets of parameters.

[0190] In one example, the WTRU may determine whether the accuracy of the prediction is acceptable, for example, whether the difference between the measured and predicted parameters is within an acceptable range (e.g., below the corresponding threshold). If the accuracy is acceptable, the WTRU may continue with the initial access procedure (e.g., Msg3 transmission) and / or connect to the detected cell. In another example, the WTRU may determine that the difference between one or more of the predicted parameters and the corresponding measured, (re)evaluated, and / or scaled parameters exceeds the corresponding threshold. The WTRU may determine that the accuracy level of the predicted SSB is not within an acceptable range. The WTRU may perform one or more steps, including following the procedures considered for selecting a second predicted SSB beam, failed PRACH transmission, conditional connection, and / or similar processing, as described herein.

Claims

1. A wireless transceiver unit (WTRU), The system comprises a processor and memory, and the processor and memory are The system receives instructions for one or more sets of transmit synchronization signal blocks (SSBs) provided in an SSB burst, and instructions for one or more sets of skipped SSBs provided in the SSB burst, and each of the one or more skipped SSBs is not transmitted by the base station in the SSB burst. The WTRU decides to send an instruction to use the first of the one or more skipped SSBs, Send a random access preamble using one or more random access resources, and one or more of the random access preambles or the one or more random access resources indicate the first skipped SSB, Using the beam associated with the first skipped SSB, receive at least one downlink transmission. WTRU is configured in such a way.

2. The aforementioned processor and memory are The system receives configuration information associated with one or more transmitted SSBs, the configuration information comprises a list of candidate beams, and the list of candidate beams comprises the beams associated with the first skipped SSB. The WTRU according to claim 1, configured as described above.

3. The WTRU according to claim 2, wherein the configuration information comprises a beam index, azimuth angle, elevation angle, or aiming angle.

4. The WTRU according to claim 1, wherein the random access preamble is transmitted using a beam associated with a first transmitted SSB of the set of one or more transmitted SSBs, and the one or more random access resources associated with the random access preamble or the first transmitted SSB indicate the first skipped SSB.

5. The WTRU according to claim 1, wherein the one or more random access resources comprises a first random access resource and a second random access resource, the first random access resource being associated with a first transmitted SSB and the second random access resource being associated with the first skipped SSB.

6. The WTRU according to claim 1, wherein the processor and memory are configured to receive a configuration indicating whether SSB skipping is possible.

7. The WTRU according to claim 1, wherein the processor and memory are configured to use an artificial intelligence (AI) / machine learning (ML) model to predict a preferred list of SSBs from the set of one or more skipped SSBs.

8. The WTRU according to claim 1, wherein the one or more random access resources are based on the one or more transmitted SSBs, the one or more skipped SSBs, or a combination of the one or more transmitted SSBs and the one or more skipped SSBs.

9. The WTRU according to claim 1, wherein the first skipped SSB of the one or more skipped SSBs is used for the initial access procedure or later.

10. The WTRU according to claim 1, wherein the instruction transmitted in the random access message 3 using the one or more random access resources indicates the first skipped SSB.

11. A method implemented by a wireless transceiver unit (WTRU), Receiving instructions for one or more sets of transmit synchronization signal blocks (SSBs) provided in an SSB burst, and instructions for one or more sets of skipped SSBs provided in the SSB burst, wherein each of the one or more skipped SSBs is not transmitted by the base station in the SSB burst. The WTRU decides to send an instruction to use the first of the one or more skipped SSBs, Sending a random access preamble using one or more random access resources, wherein one or more of the random access preambles or the one or more random access resources indicate the first skipped SSB, Using the beam associated with the first skipped SSB, to receive at least one downlink transmission, A method that includes [a certain feature].

12. Receiving configuration information associated with one or more transmitted SSBs, wherein the configuration information comprises a list of candidate beams, and the list of candidate beams comprises the beams associated with the first skipped SSB. The method according to claim 11, further comprising:

13. The method according to claim 12, wherein the configuration information comprises a beam index, azimuth angle, elevation angle, or aiming angle.

14. The method according to claim 1, wherein the random access preamble is transmitted using a beam associated with a first transmitted SSB of the set of one or more transmitted SSBs, and the one or more random access resources associated with the random access preamble or the first transmitted SSB indicate the first skipped SSB.

15. The method according to claim 1, wherein the one or more random access resources comprise a first random access resource and a second random access resource, the first random access resource being associated with a first transmitted SSB and the second random access resource being associated with the first skipped SSB.

16. It further includes receiving a configuration to determine whether SSB skipping is possible. The method according to claim 11.

17. The method according to claim 11, further comprising using an artificial intelligence (AI) / machine learning (ML) model to predict a preferred list of SSBs from the set of one or more skipped SSBs.

18. The method according to claim 11, wherein the one or more random access resources are based on the one or more transmitted SSBs, the one or more skipped SSBs, or a combination of the one or more transmitted SSBs and the one or more skipped SSBs.

19. The method according to claim 11, wherein the first skipped SSB of the one or more skipped SSBs is used for or after the initial access procedure.

20. The method according to claim 11, wherein the instruction transmitted in the random access message 3 using the one or more random access resources indicates the first skipped SSB.

Images