Methods on RACH enhancement in systems with WTRU-oriented selection of configurations for RACH transmission

Abstract

A wireless transmit / receive unit (WTRU) may comprise a processor configured to receive configuration information that may indicate that WTRU-sided timing advance (TA) prediction is enabled. The processor may be configured to receive a first set of configurations for a random access channel (RACH) transmission and a second set of configurations for a RACH transmission, determine an accuracy of a predicted TA, determine whether to use the first set of configurations or the second set of configurations for a RACH transmission, wherein the first set of configurations is used for the RACH transmission when the accuracy of the predicted TA is below a threshold value, and wherein the second set of configurations is used for the RACH transmission when the accuracy of the predicted TA is above the threshold value, and send the RACH transmission using the first set of configurations or the second set of configurations.

Description

METHODS ON RACH ENHANCEMENT IN SYSTEMS WITH WTRU-ORIENTED SELECTION OF CONFIGURATIONS FOR RACH TRANSMISSIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States Provisional Application No. 63 / 601 ,371 filed on November 21 , 2023, the entire contents of which are incorporated herein by reference.BACKGROUND

[0002] In general, in 2-step RACH (Random Access Channel), the Message A’s (MsgA’s) physical uplink shared channel (PUSCH) occasions (PCs) take large loads of time and frequency resources by considering large guard times and guard bands to avoid ISI and ICI, respectively. The guard time is used for handling the potential inter-symbol interference (ISI), as the timing of different WTRUs may exceed the CP length in RACH UL transmission, especially for long Round-Trip Time (RTT), for example, if it is a relatively large cell. The guard band is used to handle the potential inter-subcarrier interference (ICI) between WTRUs due to the timing misalignments in RACH UL transmissions.

[0003] The random access (RA) procedure may be performed via different formats for physical random access channel (PRACH) preambles, where long guard times are generally considered at the end of each RA occasion (RO) to compensate for the effects of unknown timing advance (TA) values.SUMMARY

[0004] A wireless transmit / receive unit (WTRU) may comprise a processor. The processor may be configured to receive configuration information. The configuration information may indicate that WTRU- sided timing advance (TA) prediction is enabled. The processor may be configured to receive a first set of configurations for a random access channel (RACH) transmission and a second set of configurations for a RACH transmission. The processor may be configured to determine an accuracy of a predicted TA. The processor may be configured to determine whether to use the first set of configurations or the second set of configurations for a RACH transmission, wherein the first set of configurations is used for the RACH transmission when the accuracy of the predicted TA is below a threshold value, and wherein the second set of configurations is used for the RACH transmission when the accuracy of the predicted TA is above thethreshold value. The processor may be configured to send the RACH transmission using the first set of configurations or the second set of configurations.

[0005] The second set of RACH configurations may have, for example, shortened guard bands and guard times as compared to the first set of RACH configurations.

[0006] The processor may be configured to receive a random access response (RAR) message that indicates whether the WTRU should continue to use the predicted TA or use a network provided TA. The RAR message may include, for example, the network provided TA.

[0007] The processor may be configured to determine the accuracy of the predicted TA based on any combination of time stamps of one or more reference signals (RSs), medium access control-control elements (MAC-CEs), system information blocks (SIBs), a location or position of the WTRU within a cell, a mobility state of the WTRU, a predictive model, and / or a channel impulse response (CIR) based on one or more downlink (DL) RSs.

[0008] The processor may be configured to receive configuration information that indicates the location of the WTRU. The processor may be configured to determine the distance of the WTRU from a gNB based on the WTRU’s indicated location. The processor may be configured to determine that the accuracy of the TA prediction is valid if the distance between the WTRU and the gNB is lower than a preconfigured threshold.

[0009] The processor may be configured to use a two-step RACH procedure with the second set of configurations for a RACH transmission if the accuracy of the predicted TA is above the threshold value and a measured reference signal received power (RSRP) is above an RSRP threshold for 2-step RACH. The processor may be configured to use a four-step RACH procedure with the second set of configurations for a RACH transmission if the accuracy of the predicted TA is above the threshold value and the measured RSRP is below the RSRP threshold for 2-step RACH.

[0010] Each of the first and second set of configurations may include, for example, a set of RACH time and frequency resources, a set of preambles, a RACH configuration, a preamble format, a timeAlignmentTimer (TAT) value, and / or a RSRP threshold for 2-step RACH.

[0011] The configuration information may include, for example, a flag indication that enables TA prediction for capable WTRUs. The flag indication may be via one or more of SIB, radio resource control (RRC), MAC-CE, and / or downlink control information (DCI).

[0012] The processor may be configured to use the first set of configurations for the RACH transmission if the accuracy of the predicted TA is higher than the threshold or determined to be valid. The processor may be configured to send a preamble message in a message one (MSG1) using the predicted TA.

[0013] The processor may be configured to use the second set of configurations for the RACH transmission if the accuracy of the predicted TA is higher than the threshold or determined to be valid. The processor may be configured to send a preamble message and physical uplink shared channel (PUSCH) transmission in a message A (MSGA) using the predicted TA.

[0014] The processor may be configured to start or restart a TAT based on a configured second TAT. The processor may be configured to monitor to receive a RAR message within a configured RAR window.

[0015] A WTRU may be configured to perform a method that includes one or more of the following steps. The method may include receiving configuration information. The configuration information may indicate that WTRU-sided timing advance (TA) prediction is enabled. The method may include receiving a first set of configurations for a random access channel (RACH) transmission and a second set of configurations for a RACH transmission. The method may include determining an accuracy of a predicted TA. The method may include determining whether to use the first set of configurations or the second set of configurations for a RACH transmission, wherein the first set of configurations is used for the RACH transmission when the accuracy of the predicted TA is below a threshold value, and wherein the second set of configurations is used for the RACH transmission when the accuracy of the predicted TA is above the threshold value. The method may include sending the RACH transmission using the first set of configurations or the second set of configurations.

[0016] The second set of RACH configurations may have, for example, shortened guard bands and guard times as compared to the first set of RACH configurations.

[0017] The method may include receiving a random access response (RAR) message that indicates whether the WTRU should continue to use the predicted TA or use a network provided TA. The RAR message may include, for example, the network provided TA.

[0018] The method may include determining the accuracy of the predicted TA based on any combination of time stamps of one or more reference signals (RSs), medium access control-control elements (MAC- CEs), system information blocks (SIBs), a location or position of the WTRU within a cell, a mobility state of the WTRU, a predictive model, and / or a channel impulse response (CIR) based on one or more downlink (DL) RSs.

[0019] The method may include receiving configuration information that indicates the location of the WTRU. The method may include determining the distance of the WTRU from a gNB based on the WTRU’s indicated location. The method may include determining that the accuracy of the TA prediction is valid if the distance between the WTRU and the gNB is lower than a preconfigured threshold.

[0020] The method may include using a two-step RACH procedure with the second set of configurations for a RACH transmission if the accuracy of the predicted TA is above the threshold value and a measured reference signal received power (RSRP) is above an RSRP threshold for 2-step RACH. The method may include using a four-step RACH procedure with the second set of configurations for a RACH transmission if the accuracy of the predicted TA is above the threshold value and the measured RSRP is below the RSRP threshold for 2-step RACH.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0022] FIG. 1 B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0023] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0024] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0025] FIG. 2 is a system diagram illustrating an example of a timing advance prediction based on time stamps and AI / ML systems.

[0026] FIG. 3 is a system diagram illustrating an example of a timing advance prediction based on measured parameters and AI / ML systems.DETAILED DESCRIPTION

[0027] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-sOFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0028] As shown in FIG. 1 A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a CN 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and / or a “STA”, may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a WTRU.

[0029] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the I nternet 110, and / or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0030] The base station 114a may be part of the 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), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combinationof licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0031] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0032] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0033] I n an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0034] I n an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using New Radio (NR).

[0035] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multipletypes of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., a eNB and a gNB).

[0036] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0037] The base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0038] The RAN 104 / 113 may be in communication with the CN 106 / 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 the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may be utilizing a NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0039] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or the other networks 112. The PSTN 108 may include circuit- switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0040] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0041] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / recei ve element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0042] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0043] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0044] Although the transmit / receive element 122 is depicted in FIG. 1 B as a single element, 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 wireless signals over the air interface 116.

[0045] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0046] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0047] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 maybe any suitable device for powering the WTRL1 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0048] The processor 118 may also be coupled to the 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 in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable locationdetermination method while remaining consistent with an embodiment.

[0049] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0050] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0051] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate withthe WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0052] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0053] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0054] The CN 106 shown in FIG. 1 C 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 the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0055] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0056] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter- eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0057] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0058] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0059] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0060] In representative embodiments, the other network 112 may be a WLAN.

[0061] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11 e DLS or an 802.11 z tunneled DLS (TDLS). A WLAN using an Independent BSS (I BSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad- hoc” mode of communication.

[0062] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA)may be implemented, for example in in 802.11 systems. For CSMA / CA, the ST As (e.g., every ST A), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0063] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0064] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0065] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 n, and 802.11ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine- Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0066] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In theexample of 802.11 ah, the primary channel may be 1 MHz wide for ST As (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other ST As in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0067] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0068] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0069] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0070] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wirelesstransmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0071] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0072] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0073] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0074] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b,management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and / or the like. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0075] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating WTRU IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0076] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0077] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0078] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b,eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0079] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and / or may performing testing using over-the-air wireless communications.

[0080] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0081] One of the target use-cases for Artificial Intelligence (AI)ZMachine Learning (ML) for the air interface may be beam management. AL / ML may be used as a foundation to improve performance and / or complexity in conventional beam management aspects, including beam prediction in time, and / or spatial domain for overhead and latency reduction, beam selection accuracy improvement, and / or so forth.

[0082] The random access (RA) procedure may be required at a WTRU due to different RA scenarios for which the RA report entry may be triggered. In an embodiment, examples are random accesses associated to initial access from radio resource control- idle (RRCJDLE), transition from RRC-INACTIVE and the MSG3 based system information (SI) request, beam failure recovery failure in the primary cell of a master or secondary cell group (SpCell), WTRU executing a reconfiguration with sync, random access procedure initiated in a SpCell by DL or uplink (UL) data arrival during RRC_CONNECTED when the timeAlignmentTimer (TAT) may be not running in the primary timing advance group (PTAG), by a physicaldownlink control channel (PDCCH) order in the serving cell, scheduling request (SR) failures, no valid SR physical uplink control channel (PUCCH) resources configured, MSG1 based on demand SI request, etc.

[0083] The RA procedure may be performed via different formats for PRACH preambles, where long guard times may be generally considered at the end of each RA occasion (RO) to compensate for the effects of unknown timing advance (TA) values.

[0084] In some examples, a WTRU may use a WTRU-sided system to determine, estimate, and / or predict the timing advance for the UL transmissions. The benefits may be as follows. For example, shorter ROs and more preambles availability may be one benefit. Avoidance to use long ROs, results in increased PRACH capacity, as well as availability of a greater number of preamble indexes (e.g., Zadoff-Chu root index and cyclic shifts), results in less collisions and less collision handling procedures, all results in lower latency. For example, MsgA PUSCH capacity enhancement may be another benefit. The configurations may be considered for MsgA physical uplink shared channel (PUSCH) in 2-Step RACH may be different resulting in higher modulation and coding scheme (MCS), higher throughput PUSCH, more PUSCH occasions within a slot, etc. For example, Timing Advance Command (TAC) coverage enhancement e.g., via random access response (RAR), medium access control- control element (MAC-CE), etc.) may be a benefit. TAC may have a shorter format (e.g., as there’ll be no need for TA absolute value indication) and so the RAR physical downlink shared channel (PDSCH) or MAC-CE coverage may be enhanced.

[0085] Artificial intelligence may be broadly defined as the behavior exhibited by machines. Such behavior may e.g., mimic cognitive functions to sense, reason, adapt and act.

[0086] Machine learning may refer to the type of algorithms that solve a problem based on learning through experience (‘data’), without explicitly being programmed (‘configuring set of rules’). Machine learning can be considered as a subset of Al. Different machine learning paradigms may be envisioned based on the nature of data or feedback available to the learning algorithm. For example, a supervised learning approach may involve learning a function that maps input to an output based on labeled training example, wherein each training example may be a pair consisting of input and the corresponding output. For example, an unsupervised learning approach may involve detecting patterns in the data with no preexisting labels. For example, reinforcement learning approach may involve performing sequence of actions in an environment to maximize the cumulative reward. In some solutions, it is possible to apply machine learning algorithms using a combination or interpolation of the above-mentioned approaches. For example, semi-supervised learning approach may use a combination of a small amount of labeled data with a large amount of unlabeled data during training. In this regard semi-supervised learning falls betweenunsupervised learning (with no labeled training data) and supervised learning (with only labeled training data).

[0087] Deep learning refers to a class of machine learning algorithms that employ artificial neural networks (specifically DNNs) which were loosely inspired from biological systems. The Deep Neural Networks (DNNs) are a special class of machine learning models inspired by human brain wherein the input is linearly transformed and pass-through non-linear activation function multiple times. DNNs typically consists of multiple layers where each layer consists of linear transformation and a given non-linear activation function. The DNNs can be trained using the training data via back-propagation algorithm. Recently, DNNs have shown state-of-the-art performance in variety of domains, e.g., speech, vision, natural language etc. and for various machine learning settings supervised, un-supervised, and semisupervised. The term AI / ML based methods / processing may refer to realization of behaviors and / or conformance to requirements by learning based on data, without explicit configuration of sequence of steps of actions. Such methods may enable learning complex behaviors which might be difficult to specify and / or implement when using legacy methods.

[0088] An AI / ML model may refer to an implementation of an AI / ML based method which is made up of 1) model parameters and / or 2) the model structure. For example, a DNN-based AI / ML model may include the model parameters (e.g., weights and biases) and the model structure (e.g., the types and sizes of each layer of the deep neural network such as dense layers, convolutional layers, etc.)

[0089] A WTRU may transmit or 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.

[0090] The WTRU may transmit a physical channel or signal using the same spatial domain filter as the spatial domain filter used for receiving an reference signa (RS) (such as channel state information reference signal (CSI-RS)) or a synchronization signal (SS) block. The WTRU transmission may be referred to as “target”, and the received RS or SS block may be referred to as “reference” or “source”. In such case, the WTRU may be said to transmit the target physical channel or signal according to a spatial relation with a reference to such RS or SS block.

[0091] The WTRU may transmit a first physical channel or signal according to the same spatial domain filter as the spatial domain filter used for transmitting a second physical channel or signal. The first and second transmissions may be referred to as “target” and “reference” (or “source”), respectively. In such case, the WTRU may be said to transmit the first (target) physical channel or signal according to a spatial relation with a reference to the second (reference) physical channel or signal.

[0092] A spatial relation may be implicit, configured by RRC or signaled by MAC CE or download control information (DCI). For example, a WTRU may implicitly transmit PUSCH and demodulation reference signals (DM-RS) of PUSCH according to the same spatial domain filter as an sounding reference signal (SRS) indicated by an SRS resource indicator (SRI) indicated in DCI or configured by RRC. In another example, a spatial relation may be configured by RRC for an SRI or signaled by MAC CE for a PUCCH. Such spatial relation may also be referred to as a “beam indication”.

[0093] The WTRU may receive a first (target) downlink channel or signal according to the same spatial domain filter or spatial reception parameter as a second (reference) downlink channel or signal. For example, such an association may exist between a physical channel such as PDCCH or PDSCH and its respective DM-RS. At least when the first and second signals are reference signals, such association may exist when the WTRU is configured with a quasi-colocation (QCL) assumption type D between corresponding antenna ports. Such association may be configured as a transmission configuration indicator (TCI) state. A WTRU may be indicated an association between a CSI-RS or SS block and a DM-RS by an index to a set of TCI states configured by RRC and / or signaled by MAC CE. Such an indication may also be referred to as a “beam indication”.

[0094] A transmission and reception point (TRP) may be interchangeably used with one or more of transmission point (TP), reception point (RP), radio remote head (RRH), distributed antenna (DA), base station (BS), a sector (e.g., of a BS), and a cell (e.g., a geographical cell area served by a BS), but may be consistent with this embodiment. Hereafter, Multi-TRP may be interchangeably used with one or more of MTRP, M-TRP, and multiple TRPs, but still consistent with this embodiment.

[0095] A WTRU may report a subset of channel state information (CSI) components, where CSI components may correspond to at least a CSI-RS resource indicator (CRI), a synchronization signal block (SSB) resource indicator (SSBRI), an indication of a panel used for reception at the WTRU (e.g., a panel identity or group identity), measurements such as layer on reference signal received power (L1-RSRP), layer one signal to interference plus noise ration (L1-SINR) taken from SSB or CSI-RS (e.g. cri-RSRP, cri- SINR, ssb-lndex-RSRP, ssb-lndex-SINR), and other channel state information such as at least rank indicator (Rl), channel quality indicator (CQI), precoding matrix indicator (PMI), Layer Index (LI), and / or the like.

[0096] A WTRU may receive a synchronization signal / physical broadcast channel (SS / PBCH) block. The SS / PBCH block (SSB) may include a primary synchronization signal (PSS), secondary synchronization signal (SSS), and / or physical broadcast channel (PBCH). The WTRU may monitor, receive, or attempt todecode an SSB during initial access, initial synchronization, radio link monitoring (RLM), cell search, cell switching, and / or so forth.

[0097] A WTRU may measure and report the channel state information (CSI), wherein the CSI for each connection mode may include or be configured with one or more of following.

[0098] For example, a CSI Report configuration may include an indication of CSI report quantity, such as a channel quality indicator (CQI), a rank indicator (Rl), a precoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), and / or a layer indicator (LI). The CSI Report configuration may include a CSI report type, such as aperiodic, semi persistent, periodic CSI report types. The CSI report configuration may include a CSI report codebook configuration (e.g., Type I, Type II, and / or Type II port selection). The CSI report configuration may include an indication of CSI report frequency.

[0099] In some examples, a CSI-RS Resource Set may include one or more of the following. For example, a CSI-RS Resource Set may include CSI Resource settings, for instance non-zero power (NZP) CSI-RS Resource for channel measurement, NZP-CSI-RS Resource for interference measurement, and / or CSI interference measurement (IM) Resource for interference measurement.

[0100] NZP CSI-RS Resources may include one or more of the following. For example, NZP CSI-RS Resources may include NZP CSI-RS Resource ID, periodicity and offset, quasi co-location (QCL) Information and transmission configuration indicator (TCI) state, and / or resource mapping (e.g., number of ports, density, CDM type, etc).

[0101] A WTRU may indicate, determine, and / or be configured with one or more reference signals. The WTRU may monitor, receive, and measure one or more parameters based on the respective reference signals. For example, one or more of the following may apply. The following parameters are non-limiting examples of the parameters that may be included in reference signal(s) measurements. One or more of these parameters may be included. Other parameters may be included.

[0102] A WTRU may measure SS reference signal received power (SS-RSRP) based on the synchronization signals (e.g., demodulation reference signal (DM-RS) in PBCH or SSS). SS-RSRP may be defined as the linear average over the power contribution of the resource elements (RE) that carry the respective synchronization signal. In measuring the RSRP, power scaling for the reference signals may be required. In case SS-RSRP is used for L1-RSRP, the measurement may be accomplished based on CSI reference signals in addition to the synchronization signals.

[0103] The WTRU may measure CSI-RSRP based on the linear average over the power contribution of the resource elements (RE) that carry the respective CSI-RS. The CSI-RSRP measurement may be configured within measurement resources for the configured CSI-RS occasions.

[0104] The WTRU may measure SS signal-to-noise plus interference ratio (SS-SINR) based on the synchronization signals (e.g., DM-RS in PBCH or SSS). SS-SINR may be defined as the linear average over the power contribution of the resource elements (RE) that carry the respective synchronization signal divided by the linear average of the noise and interference power contribution. In case SS-SINR is used for L1 -SI NR, the noise and interference power measurement may be accomplished based on resources configured by higher layers.

[0105] The WTRU may measure CSI-SINR based on the linear average over the power contribution of the resource elements (RE) that carry the respective CSI-RS divided by the linear average of the noise and interference power contribution. In case CSI-SINR is used for L1 -SI NR, the noise and interference power measurement may be accomplished based on resources configured by higher layers. Otherwise, the noise and interference power may be measured based on the resources that carry the respective CSI-RS.

[0106] The WTRU may measure received signal strength indicator (RSSI) based on the average of the total power contribution in configured OFDM symbols and bandwidth. The power contribution may be received from different resources (e.g., co-channel serving and non-serving cells, adjacent channel interference, thermal noise, and / or so forth).

[0107] The WTRU may measure cross-Layer interference received signal strength indicator (CU-RSSI) based on the average of the total power contribution in configured OFDM symbols of the configured time and frequency resources. The power contribution may be received from different resources (e.g., crosslayer interference, co-channel serving and non-serving cells, adjacent channel interference, thermal noise, and / or so forth).

[0108] The WTRU may measure sounding reference signals RSRP (SRS-RSRP) based on the linear average over the power contribution of the resource elements (RE) that carry the respective SRS.

[0109] The WTRU may measure secondary synchronization signal reference signal received quality (SS- RSRQ) based on measurements on the reference signal received power (SS-RSRP) and received signal strength (RSSI). In an example, the SS-RSRQ may be calculated as the ratio of NxSS-RSRP / NR carrier RSSI, where N may be determined based on the number of resource blocks that are in the corresponding NR carrier RSSI measurement bandwidth. As such, the measurements to be used in the numerator and denominator may be over the same set of resource blocks.

[0110] The WTRU may measure CSI reference signal received quality (CSI-RSRQ) based on measurements on the reference signal received power (CSI-RSRP) and received signal strength (RSSI). In an example, the SS-RSRQ may be calculated as the ratio of NxCSI-RSRP I CSI-RSSI, where N may be determined based on the number of resource blocks that are in the corresponding CSI-RSSI measurement bandwidth. As such, the measurements to be used in the numerator and denominator may be over the same set of resource blocks.

[0111] A CSI report configuration (e.g., CSI-ReportConfigs) may be associated with a single bandwidth part (BWP) (e.g., indicated by BWP-ld). A CSI report configuration may configure one or more of the following parameters. The CSI report configuration may configure CSI-RS resources and / or CSI-RS resource sets for channel and interference measurement. The CSI report configuration may configure a CSI-RS report configuration type, such as the periodic, semi-persistent, and / or aperiodic. The CSI report configuration may configure a CSI-RS transmission periodicity for periodic and semi-persistent CSI reports. The CSI report configuration may configure a CSI-RS transmission slot offset for periodic, semi-persistent and / or aperiodic CSI reports. The CSI report configuration may configure a CSI-RS transmission slot offset list for semi-persistent and / or aperiodic CSI reports. The CSI report configuration may configure time restrictions for channel and / or interference measurements. The CSI report configuration may configure a report frequency band configuration (e.g., wideband / subband CQI, PMI, and / or so forth). The CSI report configuration may configure thresholds and / or modes of calculations for the reporting quantities (e.g., CQI, RSRP, SINR, LI, Rl, etc.). The CSI report configuration may configure a codebook configuration. The CSI report configuration may configure group based beam reporting. The CSI report configuration may configure a CQI table. The CSI report configuration may configure a subband size. The CSI report configuration may configure a non-PMI port indication. The CSI report configuration may configure a Port Index.

[0112] In CSI-RS resource configuration, a CSI-RS resource set (e.g., NZP-CSI-RS-ResourceSet) may include one or more of CSI-RS resources (e.g., NZP-CSI-RS-Resource and CSI-ResourceConfig), where a WTRU may be configured with one or more of the following in a CSI-RS Resource. For example, a WTRU may be configured with CSI-RS periodicity and slot offset for periodic and semi-persistent CSI-RS Resources. A WTRU may be configured with CSI-RS resource mapping to define the number of CSI-RS ports, density, CDM-type, OFDM symbol, and / or subcarrier occupancy. A WTRU may be configured with the bandwidth part to which the configured CSI-RS is allocated. A WTRU may be configured with the reference to the TCI-State including the QCL source RS(s) and the corresponding QCL type(s).

[0113] In RS resource set configuration, one or more of following configurations may be used for RS resource set. For example, a WTRU may be configured with one or more RS resource sets. The RS resource set configuration may include one or more of following. For instance, the RS resource set configuration may include RS resource set ID. The RS resource set configuration may include one or more RS resources for the RS resource set. The RS resource set configuration may include repetition (e.g., on or off). The RS resource set configuration may include aperiodic triggering offset (e.g., one of 0-6 slots). The RS resource set configuration may include tracking reference signal (TRS) information (e.g., true or not).

[0114] In RS resource configuration, one or more of the following configurations may be used for RS resource. A WTRU may be configured with one or more RS resources. The RS resource configuration may include one or more of following. For example, the RS resource configuration may include RS resource ID. The RS resource configuration may include resource mapping (e.g., REs in a physical resource block (PRB)). The RS resource configuration may include power control offset (e.g., one value of -8, ..., 15). The RS resource configuration may include power control offset with SS (e.g., -3 dB, 0 dB, 3 dB, 6 Db). The RS resource configuration may include scrambling ID. The RS resource configuration may include periodicity and offset. The RS resource configuration may include QCL information (e.g., based on a TCI state).

[0115] The WTRU may receive a grant or assignment. A property of a grant or assignment may include at least one of the following. For example, a property of a grant or assignment may include a frequency allocation. A property of a grant or assignment may include an aspect of time allocation (e.g., such as a duration). A property of a grant or assignment may include a priority. A property of a grant or assignment may include a modulation and coding scheme (MCS). A property of a grant or assignment may include a transport block size. A property of a grant or assignment may include a number of spatial layers. A property of a grant or assignment may include a number of transport blocks. A property of a grant or assignment may include a TCI state, an indication of CRI or SRI. A property of a grant or assignment may include a number of repetitions. A property of a grant or assignment may include an indication of whether the repetition scheme is Type A or Type B. A property of a grant or assignment may include an indication of whether the grant is a configured grant type 1 , type 2 or a dynamic grant. A property of a grant or assignment may include an indication of whether the assignment is a dynamic assignment or a semi- persistent scheduling e.g., configured) assignment. A property of a grant or assignment may include a configured grant index or a semi-persistent assignment index. A property of a grant or assignment may include a periodicity of a configured grant or assignment. A property of a grant or assignment may include achannel access priority class (CAPC). A property of a grant or assignment may include one or more parameters provided in a DCI, by MAC or by RRC for the scheduling the grant or assignment.

[0116] An indication by DCI may include an explicit indication by a DCI field or by RNTI used to mask or scramble the CRC of the DCI. The indication by DCI may include an implicit indication by a property, for example, such as DCI format, DCI size, control resource set (CORESET) or search space, aggregation Level, and / or first resource element of the received DCI (e.g., index of first control channel clement (CCE)). The mapping between the property and the value may be signaled by RRC or MAC.

[0117] In some examples, receiving or monitoring for a DCI with or using an RNTI may mean that the CRC of the DCI is masked or scrambled with the radio network temporary indentifier (RNTI).

[0118] A signal may be interchangeably used with one or more of following. For example, a signal may be interchangeably used with a sounding reference signal (SRS). A signal may be interchangeably used with a channel state information - reference signal (CSI-RS). A signal may be interchangeably used with a demodulation reference signal (DM-RS). A signal may be interchangeably used with a phase tracking reference signal (PT-RS). A signal may be interchangeably used with a synchronization signal block (SSB).

[0119] A channel may be interchangeably used with one or more of following. For example, a channel may be interchangeably used with a physical downlink control channel (PDCCH). A channel may be interchangeably used with a physical downlink shared channel (PDSCH). A channel may be interchangeably used with a physical uplink control channel (PUCCH). A channel may be interchangeably used with a physical uplink shared channel (PUSCH). A channel may be interchangeably used with a physical random access channel (PRACH).

[0120] The operational states of a WTRU may be categorized into one or more RRC states, where the states may include, for example, RRC Idle state, RRC Inactive state, and / or RRC Connected state, etc.

[0121] A signal, channel, and / or message (e.g., as in DL or UL signal, channel, and message) may be used interchangeably. RS may be interchangeably used with one or more of RS resource, RS resource set, RS port and / or RS port group. RS may be interchangeably used with one or more of SSB, CSI-RS, SRS, and DM-RS, TRS, positioning reference signal (PRS), and / or PTRS. Time instance, slot, symbol, and / or subframe may be used interchangeably. The terms SSB, SS / PBCH block, primary SS (PSS), secondary SS (SSS), PBCH, and / or master information block (MIB) may be used interchangeably. SSB, SSB beam, and / or SSB index may be used interchangeably. The proposed solutions estimation and / or prediction may be used for transmissions and / or receptions belonging to a single or multiple cells as well as single or multiple TRPs. CSI reporting may be interchangeably used with CSI measurement, beamreporting and / or beam measurement. A RS resource set may be interchangeably used with a beam group. The terms prediction, estimation, calculation, evaluation, and / or determination may be used interchangeably.

[0122] FIG. 2 is a system diagram illustrating an example of timing advance prediction based on time stamps and AI / ML systems. A timing advance (TA) prediction-capable WTRU may perform TA prediction based on one or more input values. In some examples, the TA-prediction-capable WRTU may perform TA prediction based on Time Delay. For example, the WTRU may consider a scenario where a WTRU-sided (e.g., AI / ML) model may be able to predict the timing advance and / or UL timing adjustments for the detected and / or predicted SSBs or one or more reference signal (RS) resources. The WTRU that has been triggered or has determined to perform initial access and / or random access may be able to estimate the timing advance for the received SSBs or RS signals (e.g., based on the AI / ML systems), where any combination of the following inputs may be considered.

[0123] The WTRU may consider a transmission time stamp along with the received SSBs (e.g., via SIB) or reference signals, indicated for example as SSBi TS in system diagram 200. The WTRU may consider measured SSB or RSs’ channel impulse responses (CIR) that may be used to estimate the propagation delay, indicated for example as SSBi CIR in system diagram 200. The WTRU may consider a reception time stamp corresponding to the received SSBs or RSs, indicated for example as SSBi reception time stamp (Rx TS) in system diagram 200. The reception time stamp may be calculated based on the global positioning system (GPS) or global navigation satellite system (GNSS) time stamps that have the accuracy of 2ns.

[0124] The TA-prediction-capable WRTU may perform TA prediction based on the reception of transmission time stamp of one or more SSBs, RSs, etc. and use that to perform TA prediction, for example, in addition to the measured SSBs’, RSs’ CIR, a determined reception time stamp for the received SSBs, DCI, RSs, etc., and / or configurations (e.g., TA prediction configurations). For example, the WTRU may determine or be configured to perform TA prediction based on received time stamps as part of the received DCIs (e.g., DCI indicating an (e.g., aperiodic) RS transmission, DCI including PDCCH order, DCI indicating a dynamic grant, DCI indicating a TCI-state, etc.), and / or any combination of SSB, CSI-RS, PDCCH, PDSCH, etc. The WTRU may determine or be configured to perform TA prediction periodically, aperiodically, or semi-persistently or event-based.

[0125] The TA-prediction-capable WRTU may perform TA prediction based on RS measurements. The network (NW) sided model may be trained and transferred to WTRUs based on measurements in the cell(e.g, serving cell, non-serving cell, etc.). As such, the measurements on RSs may be used as input and TA prediction may be achieved as output.

[0126] In some examples (e.g., AI / ML system), the NW may train the model based on fingerprinting according to the WTRUs’ measurements on SSBs and / or RSs throughout the cell and the corresponding measured TA values. The model may be transferred to be used at the WTRU side. The WTRU then may measure one or more parameters (e.g., RSRP, SINR, reference signal received quality (RSRQ), etc.) based on SSBs or other configured RSs from the cell and use the model (e.g., AI / ML) to predict the TA accordingly, for example, as shown in FIG. 3. FIG. 3 is a system diagram illustrating an example of timing advance prediction based on measured parameters and AI / ML systems.

[0127] A timing advance may be defined based on a, for example, cell-specific timing advance offset (e.g, ^TA offset) and / or for example a WTRU-specific timing advance (e.g., WTA). The timing advance may reflect into the time for which an uplink slot / frame transmission may take place before the start of the corresponding downlink slot / frame from the serving cell. The timing advance may be determined based on ( / VTA+ WTA offset) x Tc.) The timing advance offset may be a cell-specific time parameter that depends on the Duplex mode, the frequency range (FR), and / or so forth. A WTRU may receive one or more timing advance commands (TAC), for example from a gNB, for example e.g., via MAC CE, for initiating, increasing, or decreasing the timing advance (e.g., WTA). WTAand WTA offsetmay be provided as described below, for example, except for MsgA transmission on PUSCH where WTA= 0 may be used.

[0128] As an example, the WTRU may receive a TAC (e.g., via MAC CE) along with a random-access response and through an index value (e.g., TA- 0,1,2, ... ,3846), where the timing advance may be determined accordingly (e.g., / VTA= TA■ 16 ■ 64 / 2|U, for SCS of 2M■ 15 kHz). In another example, a WTRU may receive a TAC (e.g., via MAC CE) to adjust the existing timing advance (e.g., / VTA old) to a new value (e.g., WTA_new) through an index value (e.g., TA= 0,1,2, ... ,63), where the timing advance may be determined accordingly (e.g, / VTA new= / VTA old+ (TA- 31) ■ 16 ■ 64 / 2^, for SCS of 2A' ■ 15 kHz).

[0129] In an example, a WTRU may determine or be configured to perform UL timing adjustment and / or timing advance (TA) determination, prediction, and / or estimation based on one or more measured and / or configured parameters. The one of solutions for performing TA estimation and / or prediction at the WTRU may be provided as an embodiment. For example, the WTRU may perform TA prediction and / or estimation based on AI / ML systems, see FIG. 2 and FIG. 3. In an example, the WTRU may perform TA prediction and / or estimation based on the time delay between the transmission time at the gNB and the reception timeat the WTRU for one or more DL signals and / or channels (e.g., SSB, CSI-RS, PDCCH, PDSCH, etc.). In another example, the WTRU may perform TA prediction and / or estimation for a cell based on one or more received DL RSs and / or SSBs, the measured parameters, and / or a trained model.

[0130] For example, one or more of the following procedures may apply. The following procedures and / or parameters are non-limiting examples of the procedures that may be included in TA determination, prediction, and / or estimation. One or more of these procedures and / or parameters may be included. Other procedures and / or parameters may be included.

[0131] The WTRU may perform TA prediction and / or estimation based on a time delay. In an example, the WTRU may determine, estimate, and / or predict the timing advance for UL transmission based on calculating, measuring, determining, and / or estimating the time difference between transmission time stamp of a DL (e.g., from a gNB) and the reception time stamp at the WTRU. For example, the WTRU may use one or more of the following parameters.

[0132] The WTRU may use a parameter such as a transmission time stamp. For example, the WTRU may receive the transmission time stamp of one or more reference signals and / or channels. In an example, upon detection and / or reception of an SSB, the WTRU may monitor to receive one or more system information blocks (SIBs) (e.g., SIB1 , SIB2, etc.) that may include the time stamp that indicates the time at which the SSB was transmitted (e.g., from the gNB). In another example, upon reception of a PDCCH, that may for example include a DCI, the WTRU may receive the time stamp, for example as part of the DCI, that indicates the time at which the PDCCH was transmitted (e.g., from the gNB). In another example, upon reception of a PDSCH, that may for example include a MAC-CE, the WTRU may receive the time stamp, for example as part of the PDSCH or MAC-CE, that indicates the time at which the PDSCH was transmitted (e.g., from the gNB). In another example, upon reception of a reference signal (RS) (e.g., CSI-RS, PTRS, TRS, etc.), the WTRU may determine and / or receive the time stamp that is embedded as part of the sequence used in generating the reference signal. The determined time stamp may indicate the time at which the corresponding RS was transmitted (e.g., from the gNB).

[0133] The WTRU may use a parameter such as Channel Impulse Responses (CIR) to perform TA prediction and / or estimation. For example, the WTRU may measure, calculate, and / or determine the CIR based on one or more DL RSs, for example to estimate the propagation delay. In an example, the WTRU may determine, be configured, or receive configurations on the DL RS to be used for measuring the CIR. For example, the WTRU may receive configuration information or indications via RRC, MAC-CE, DCI, SIB, MIB, etc., for example including PDCCH order, indicating the resources to be used for CIR measurement.

[0134] In an example, the WTRU may determine, be configured, and / or be indicated to use one or more SSB indexes, RS indexes, and / or TCI states, etc. as DL reference signals for CIR measurement.

[0135] In another example, the WTRU may determine, be configured, and / or indicated to use one or more RSs received as part of PDCCH, PDSCH, and / or so forth as DL reference signals for CIR measurement. For example, one or more configured, indicated, and or received PDCCHs, PDSCHs, PBCHs, and / or so forth may include one or more reference signals, including for example a demodulation reference signal (DM-RS). In an example, the WTRU may determine or receive configuration and / or indication to use PDCCH DM-RS, PDSCH DM-RS, and / or PBCH DM-RS.

[0136] The WTRU may use a parameter such as reception time stamp to perform TA prediction and / or estimation. For example, the WTRU may calculate and / or determine the reception time stamp for a determined, configured, and / or indicated DL signal or channel. The reception time stamp may indicate the time at which the corresponding DL signal or channel was received. In an example, the DL signals and / or channels may indicate one or more received SSB, CSI-RS, TRS, PTRS, transmission configuration indicator (TCI) state, PDCCH, PDSCH, and / or so forth. For example, the WTRU may use Global Navigation Satellite System (GNSS), Global Positioning System (GPS), and / or so forth for acquiring the reception time stamp.

[0137] In an example, the WTRU may perform TA prediction and / or estimation based on AI / ML systems. An example of an AI / ML model is provided in FIG. 2, where the model provides the predicted TA as the output of the model based on the input values to the model. For example, the inputs to the model may include one or more of the following.

[0138] In some examples, the inputs to the model may include a transmission time stamp, for example, that is shown as SSBs’ transmission (Tx) time stamp for example in FIG. 2, indicated as “SSBi TS”. The inputs to the model may include a CIR, for example, as shown as SSBs’ CIR for example in FIG. 2, indicated as “SSBi CIR”. The inputs to the model may include a Reception time stamp, that is shown as SSBs’ reception (Rx) time stamp for example in FIG. 2, indicated as “SSBi Rx TS” in FIG. 2.

[0139] In an example, a WTRU in RRC-Connected and / or RRC-lnactive modes may be in-sync with the NW and / or cell (e.g., a gNB). The WTRU may be synchronized with the gNB’s timing and clock. The WTRU may be able to use the time stamps associated with a transmitted reference signal, for example SSB, CSI- RS, etc. In another example, a WTRU in RRC-ldle mode may acquire the time synchronization based on one or more sources or entities, for example, GPS, GNSS, etc.

[0140] The WTRU may perform TA prediction according to mappings based on fingerprintings. In an example, the WTRU may perform TA prediction and / or estimation based on trained models, for example in an AI / ML systems. An example AI / ML model is provided in FIG. 3, where the model provides the predicted TA as the output of the model based on the input values to the model. For example, the NW may train a model based on fingerprinting according to the WTRUs’ measurements on SSBs and / or RSs in addition to the corresponding measured TA values. The model may be transferred to be used at the WTRU side. As such, in an example, the WTRU may measure one or more parameters based on SSBs (“SSB measured param” in system diagram 300) and / or one or more RSs (“RS / measured param” in system diagram 300) and use the measurements as inputs to predict the TA accordingly. In an example, the measured parameters may include RSRP, RSRQ, SINR, etc. based on the received RSs (e.g., SSB).

[0141] In another example, the WTRU may be able to determine the TA based on other means or methods. For example, the WTRU may have a mapping table of one or more measured parameters and corresponding TAs. In an example, the mapping table may be sent to or configured for the WTRU after the network has made the fingerprinting. In another example, the mapping may be performed based on a neural network that has been trained at the network for the sake of the WTRU that may take measurements as an input and provides the TA as output.

[0142] In an example, a WTRU in RRC-Connected and / or RRC-lnactive modes may be (pre)configured and / or receive one or more configurations, for example from a gNB, on transferring the trained models. The WTRU may use the transferred trained model for TA prediction and / or determination. In another example, a WTRU in RRC-ldle mode may already be (pre)configured or equipped with one or more models for TA prediction and / or training. The WTRU may verify the model used at the cell and determine if the available model at the WTRU is valid or not. In an example, the WTRU may be configured with a model with a first model ID or model index. For example, the WTRU may receive an indication, for example from a gNB, for example via MIB, SIB, etc., on a second model index and / or model ID that may be valid to be used for WTRU-sided TA prediction. If the indicated second model ID is the same as the configured first model ID, the WTRU may determine to use the model for WTRU-sided TA prediction in RRC-ldle mode.

[0143] Training and / or updating TA prediction model may be described. In an example, a WTRU may do one or more of the following. A TA-prediction-capable WTRU may determine or receive indication from gNB to perform TA prediction AI / ML model training or model update (e.g., in RRC-Connected Mode). Based on the determination, the WTRU may send an indication to the gNB indicating the TA prediction model training.

[0144] The WTRU may be configured to, and / or may determine and / or receive configuration information on a time duration and / or window to perform verification for the TA prediction AI / ML model training (e.g., the WTRU may perform the verification even in RRC-IDLE-Mode).

[0145] During the configured and / or determined time window, the WTRU may perform TA prediction based on one or more input values and AI / ML models.

[0146] During the time window, the WTRU may send one or more UL signals or channels to gNB (e.g., PRACH, SRS, early PRACH in LTM, PUCCH, PUSCH, etc.) and receive the actual TA values.

[0147] The WTRU may use the difference between the actual time values and the predicted TAs for training the model. If the difference between the actual time values and the predicted TAs for training the model is higher than a threshold, the WTRU may initiate training / updating the models. If the difference between the actual time values and the predicted TAs for training the model is lower than the threshold, the WTRU may do not initiate training procedure. The WTRU may restart the timeAlignmentTimer (TAT) or start the TAT with a second (e.g., extended or increased) determined or (pre)configured TAT value.

[0148] The WTRU may report the difference and the decision on whether to perform training and / or updating to the gNB.

[0149] In an example, a WTRU may determine, receive, or be configured with one or more configuration information and / or indications indicating the WTRU to activate and / or perform training or updating and / or fine tuning for the system that may be used for TA prediction, estimation, calculation, and / or determination (e.g., AI / ML model). For example, the configuration and / or indications may be based on WTRU’s capability. In an example, the WTRU may receive the indication and / or configuration, for example from a gNB, via RRC, MAC-CE, DCI, etc.

[0150] For example, the WTRU that may be capable of TA prediction may determine and / or receive an indication to activate the system’s model updating and / or training. In an example, the WTRU that may have installed and / or implemented or may be configured with a model capable of TA prediction, may determine or receive an indication to activate model training and / or updating. In an example, the WTRU may activate model training if the model to be used for TA prediction does not exist in WTRU’s memory and / or storage.

[0151] In another example, the WTRU may receive an additional indication indicating the WTRU to either perform AI / ML model training, fine tuning, and / or updating. For example, the WTRU may receive a flag indication where a first value (e.g., value one) may indicate a first procedure (e.g., model training activation) and a second value (e.g., value zero) may indicate a second procedure (e.g., model fine tuning and / or updating).

[0152] In case the WTRLI may determine to perform TA prediction’s model training and / or updating, the WTRU may send an indication (e.g., to a gNB). The WTRU may send the indication to indicate that the WTRU has determined and may initiate model training and / or updating. The WTRU may send the indication as part of CSI reporting, PUCCH, PUSCH, and / or so forth, via uplink control information (UCI), MAC-CE, RRC, etc. The indication may include the start time and the time duration of the model training and / or updating. The indication may include WTRU’s determined procedure to be performed. In an example, the WTRU may send an indication (e.g., 2-bits indication), where a first value (e.g., 00) may indicate a first selection (e.g., model training), a second value (e.g., 01) may indicate a second selection (e.g., model updating), a third value (e.g., 10) may indicate a third selection (e.g., no model updating or training is required), and / or so forth.

[0153] In an example, a WTRU may determine, be configured, and / or receive one or more configuration information on one or more time window and / or time durations. For example, the WTRU may receive the configured time configurations as part of the received model’s training and / or updating activation indication. In an example, the time window and / or duration may be determined, configured, and / or indicated based on time instances, for example number of symbols, slots, subframes, and / or in absolute value time units (e.g., msec, micro-sec, etc.).

[0154] A procedure to verify and / or validate the model and determine if training and / or updating may be implemented. In an example, a WTRU may perform verification and / or validation of the TA prediction model within the determined and / or configured time window. The WTRU may perform the model’s validation in order to determine whether model training and / or updating is required. In an example, the WTRU may determine or be configured to perform the validation procedure in RRC-Connected mode, in both RRC- Connected and RRC-ldle mode, or in RRC-ldle mode. One or more of the following may apply.

[0155] For example, a TA prediction may apply. During the configured or determined time window, the WTRU may perform TA prediction based on one or more determined and / or configured DL RSs in addition to the other inputs to the model (e.g., RS’s transmission time stamp, RS’s channel impulse response, RS’s reception time, etc.).

[0156] UL transmission and reception of actual measured TA value may apply. For example, during the configured or determined time window, the WTRU may transmit one or more determined and / or configured UL signals and / or channels. In an example, the WTRU may be configured or receive one or more configuration information on one or more UL transmission occasions (e.g., PRACH, SRS, PUSCH, PUCCH, etc.) scheduled within the configured time window. As such, the WTRU may transmit one or moreof the configured UL signals and / or channels based on the configured UL resources. Based on the WTRU’s UL transmission, the WTRU may receive actual measured TA values (e.g., based on network-measured TA). The WTRU may receive the absolute measured TA values or TA adjustments based on the TA used for the transmission of the determined and / or configured UL occasions. In an example, the WTRU may receive the TA adjustments and / or absolute value via a timing advance command (TAC), for example via MAC-CE, DCI, etc.

[0157] Comparing the predicted TA with measured TA values may be implemented. Upon reception of the actual measured TA value, the WTRU calculates the difference between the predicted TA and the received measured TA.

[0158] Determining to perform model training or updating may be implemented. If the calculated difference is higher than a first configured threshold, the WTRU may determine that the TA prediction model may require model training. If the calculated difference is lower than the first threshold but higher than a second threshold, the WTRU may determine that the TA prediction model may require model updating. If the calculated difference is lower than the second threshold, the WTRU may determine that no model training and / or updating is required. If no model updating or training is required, the WTRU may start and / or restart the TAT, where the TAT may be based on a previously determined and / or configured first TAT. Additionally and / or alternatively, the WTRU may be configured or determine to use a second configured and / or determined TAT, that may be longer than the first TAT. The WTRU may receive the first and the second thresholds for the difference between the predicted and measured TA, for example via RRC, MAC-CE, DCI, etc. The WTRU may receive the first and second thresholds as part of the received activation indication and configuration.

[0159] The WTRU may determine or be configured to send an indication, for example to a gNB, indicating the WTRU’s determined action for the model based on the outcome of validation procedure. The WTRU may indicate whether model training or model updating is required. The WTRU may indicate if no model training and updating is required. The WTRU may send the indication, for example via UCI, MAC-CE, RRC, etc.

[0160] Evaluation of accuracy of the WTRU-sided TA determination may be implemented. In an example, a WTRU capable of performing TA prediction may determine or be configured to validate the accuracy of the predicted TA. For example, the WTRU may determine if the accuracy of the TA prediction model is valid or invalid. In an example, the WTRU may determine the validity of the accuracy based on one or more measurements in addition to one or more determined, received, and / or configured thresholds, and / or soforth. In an example, the WTRU may receive configurations and / or indications, for example from a gNB. The WTRU may determine and / or be configured to perform the validation of the model based on one or combination of the following examples are suggested.

[0161] In some examples, the WTRU may determine and / or be configured to perform the validation of the model based on position and time stamps. In an example, the WTRU may determine the accuracy of the TA prediction based on one or more determined and / or received positioning information. In an example, the WTRU may receive, determine, and / or estimate WTRU’s position in the cell. For example, the WTRU may use GPS assisted location and / or position determination tools, models, and / or systems. In an example, the WTRU may determine, be configured, and / or receive configuration information on the location of one or more Tx and / or Rx modules or entities within the cell, for example the location of the gNB. For example, the WTRU may receive the configuration information, for example via SIB, RRC, MAC-CE, and / or DCI signaling. In an example, the WTRU may determine the distance from the gNB based on WTRU’s determined location and / or position and the received location and / or position of the gNB.

[0162] In an example, the WTRU may determine that the accuracy of the TA prediction is valid, if the distance between the WTRU and gNB is lower than a determined and / or (pre)configured threshold. For example, the WTRU may receive the threshold, for example from the gNB, for example via SIB, RRC, MAC-CE, DCI, and / or so forth. In an example, the WTRU may determine that if the WTRU is close enough to the gNB, the determined and / or measured time stamps, time delays, propagation delays, and therefore the predicted TA is valid. For example, if the WTRU is located within less than 100m distance from the gNB, the WTRU may determine that the accuracy of the predicted TA is valid and therefore the WTRU may use the predicted TA for further configured and / or determined UL transmissions. In an example, if the distance between the WTRU and the gNB is longer than the determined and / or configured threshold, the WTRU may determine that the accuracy of the predicted TA may be invalid. In some examples, the TA may be based on a distance threshold value that may be configured and / or indicated from the gNB via SIB, RRC, MAC-CE and / or DCI, etc.

[0163] In an example, a WTRU may estimate the accuracy of a first predicted and / or determined timing advance based on the received, estimated, and / or determined position and / or location of the WTRU with regards to the cell. For example, the WTRU may receive and / or estimate its position and / or location within the cell (e.g., by using a GPS assisted location and / or position determination, etc.). In an example, the WTRU may receive and / or determine the location of the gNB, where the WTRU may receive theinformation, for example via SIB, RRC, MAC-Cem DCI, etc. The WTRU may determine the distance between WTRU and the gNB.

[0164] In an example, the WTRU may estimate and / or calculate a second TA value based on the determined distance between the WTRU and the gNB, where the WTRU may compare the second estimated TA value with the first predicted TA. For example, the WTRU may determine that the accuracy of TA prediction is valid if the difference between the first predicted TA and the second estimated TA is lower than a configured and / or determined threshold. In an example, the WTRU may determine the threshold based on the CP length, for example equal to or as a function of the CP length. In another example, the WTRU may receive configuration information on the threshold (e.g., from the gNB, via RRC, MAC-CE, and / or DCI, etc.).

[0165] The WTRU may determine and / or be configured to perform the validation of the model based on mobility status. In an example, the WTRU may determine the accuracy of TA predictions based on the mobility status of the WTRU.

[0166] For example, the WTRU may receive one or more thresholds on the level of mobility, for instance from the gNB. In an example, the WTRU may receive one or more thresholds, for example for the speed, for the number of times that the WTRU changes its direction of movement within a preconfigured time window, etc.

[0167] For example, the WTRU may be configured with a first state of mobility that is static and with very low speed movements (e.g., speed lower than a first threshold). The WTRU may be configured with a second state of mobility that is medium speed movements (e.g., speed higher than the first threshold and lower than a second threshold). The WTRU may be configured with a third state of mobility that is high speed movements (e.g., speed higher than the second threshold), etc.

[0168] In an example, the WTRU may determine that the accuracy of the TA prediction may be highest if the WTRU is in the first state of mobility. The WTRU may determine that the accuracy of the TA prediction may be lower if the WTRU is in the second state of mobility. The WTRU may determine that the accuracy of the predicted TA is lowest if the WTRU is in the third state of mobility, etc.

[0169] In an example, a WTRU may determine one or more accuracy thresholds based on WTRU’s state of mobility. In an example, the WTRU may determine that the granularity to predict TA may be a first granularity in case the WTRU is in the first state of mobility. The WTRU may determine the accuracy threshold that can be achieved if the WTRU is in the first state of mobility. In another example, the WTRU may determine the granularity to predict TA may be a second or third granularity in case the WTRU is in thesecond or third state of mobility, respectively. The WTRU may determine the accuracy threshold that can be achieved if the WTRU is in the second or third state of mobility, accordingly. In an example, the granularity may be based on one or more time units (e.g., ms, microsecond, etc.). In another example, the granularity may be based on one or more time instances (e.g., symbol, CP length, slot, etc.).

[0170] In an example, the WTRU may report the determined accuracy threshold and / or granularity (e.g., to the gNB, via UCI, MAC-CE, and / or RRC, etc.). As such, the gNB may use the received accuracy thresholds to determine whether to enable and / or disable the prediction, for example of the TA, at the WTRU, as part of the configuration information that is transmitted to the WTRU.

[0171] In another example, a WTRU may determine the periodicity to perform measurements and / or prediction based on WTRU’s state of mobility. In an example, the WTRU may determine that the time period or the time duration to predict TA may be a first, a second, a third, etc. time value in case the WTRU is in the first, second, or third state of mobility, respectively. In an example, the WTRU may report the determined time period and / or time duration (e.g., to the gNB, via UCI, MAC-CE, and / or RRC, etc.) The gNB may use the received time period and / or time duration to determine whether to enable and / or disable TA prediction at the WTRU, as part of the configuration information that is transmitted to the WTRU.

[0172] The WTRU may determine and / or be configured to perform the validation of the model based on SIB Information. In an example, a WTRU may determine the accuracy of TA predictions with the support of time stamps received (e.g., from a gNB, via SIB). In an example, the WTRU may use the time stamps received via GPS as input for the model to predict TA. The WTRU may also receive a high granularity time stamp from the gNB to determine the accuracy of the time stamps used for TA predictions. For example, the WTRU may receive a SIB dedicated for high accuracy time stamp transmission. The dedicated SIB may be transmitted periodically, aperiodically (e.g., as response to a request from the WTRU), or semi- persistently.

[0173] In an example, the WTRU may use the received time stamp via SIB and compare with the time stamps received from the GPS to determine if the accuracy of the received time stamp is valid. In an example, if the time stamps received from the GPS are determined to be valid, the WTRU may determine that the TA predictions may be valid. In an example, if the time stamps received from the GPS are determined to be invalid, the WTRU may determine that the TA predictions may be invalid.

[0174] The WTRU may perform one or more actions based on the validation results. In an example, based on the determined validity of the TA prediction, a WTRU may determine to use or not to use thepredicted TA. In an example, the WTRU may determine to enable or disable the TA prediction procedure. In another example, the WTRU may determine to perform model training and / or updating.

[0175] In an example, if the WTRU determines to use TA prediction, the WTRU may use a second determined and / or (pre)configured TAT value, where the second TAT may be extended or longer than the previously configured and / or determined first TAT. For example, the WTRU may determine or be configured to use the first configured TAT for operating without WTRU-sided TA prediction and / or determination.

[0176] In an example, the WTRU may report the determined status of the TA predication accuracy (e.g., to the gNB, via UCI, MAC-CE, and / or RRC, etc.). For example, the WTRU may indicate if the determined accuracy of the TA prediction is valid or invalid. The report may include the predicted TA value.

[0177] The WTRU may determine and / or be configured to perform the validation of the model based on the model. In an example, a WTRU may determine the accuracy of the prediction based on the received and / or (pre)configured trained model. In an example, the WTRU may be provided with a trained model, for example in an AI / ML systems, where the model may be trained by the NW.

[0178] For example, the NW may train a model based on fingerprinting according to the WTRUs’ measurements on SSBs and / or RSs in addition to the corresponding WTRU-sided predicted TAs and / or NW-sided measured TA values. For instance, the NW may collect the WTRUs’ data on the measurements in addition to the WTRU-sided predicted and / or determined TA values. Additionally and / or alternatively, the NW may associate the collected WTRUs’ data with the (actual) measured TA values at the NW side. The trained model may be in the form of a mapping that is based on fingerprinting data from WTRUs.

[0179] The model may be transferred to be used at the WTRU side. In an example, the WTRU may measure one or more parameters based on SSBs and / or one or more RSs and may use the measurements as inputs to the model. In an example, the output of the model may be the predicted TA in addition to the accuracy or the granularity of the predicted TA. In an example, the measured parameters may include RSRP, RSRQ, SINR, etc. based on the received RSs (e.g., SSB).

[0180] In another example, the WTRU may be able to determine the TA prediction accuracy based on other means (e.g., the WTRU may have a mapping table of one or more measured parameters and corresponding predicted TA accuracies). In an example, the mapping table may be sent to or configured for the WTRU after the network has made the fingerprinting. In another example, the mapping may be performed based on a neural network that has been trained at the network for the sake of the WTRU that takes measurements as an input and provides the TA and / or TA prediction accuracy as output.

[0181] In an embodiment, a WTRU may be configured with two sets of RACH resources. The WTRU may determine whether to use the first or second set of RACH resources based on whether the WTRU is incapable or capable of WTRU-sided timing alig nment / adj ustment for UL transmissions. The WTRU may detect and / or receive one or more SSB indexes during initial and / or random access. The WTRU may measure corresponding RSRP values. The WTRU may determine and / or receive triggers to perform a RACH procedure associated with one of the SSB indexes (e.g., with the highest RSRP, indicated via PDCCH order, based on beam failure recovery (BFR) configs., etc.).

[0182] The WTRU may receive configuration information regarding WTRU-sided Timing Advance (TA) determination, for example, including a flag indication (e.g., via SIB, RRC, MAC-CE, and / or DCI) that allows and / or enables TA prediction for capable WTRUs. If the WTRU is enabled for WTRU-sided TA determination, the WTRU may receive a first (e.g., legacy) set of configurations and a second set of configurations for RACH transmission (e.g., via MIB, SIB, RRC, MAC-CE, and / or DCI, etc.).

[0183] Each of the first and second set of configurations may include any of the following (e.g., where the values are unique to the first and second set of configurations): a set of RACH time and freq, resources, a set of preambles (e.g., such that the second set has more number of preambles than the first set), RACH configs (e.g., where the second RACH config has shortened guard bands and guard time), preamble formats (e.g., where the second preamble format has short preambles), and / or a timeAlignmentTimer (TAT) value (e.g., where the second TAT value may be longer than the first TAT value).

[0184] Each of the first and second sets of configurations may include MsgA configurations for 2-step RACH that may include any combination of the following: PUSCH time and freq, resources, PUSCH mapping type, PUSCH starting symbol S (e.g., non-zero S), PUSCH length L (e.g., second PUSCH length may be shorter than first PUSCH length), PUSCH MCS (e.g., second MCS may be higher than first MCS), a MsgA RSRP threshold (e.g., second RSRP threshold may be lower than first RSRP threshold). The MsgA configurations may be unique to the first and second set of configurations.

[0185] The WTRU may be configured for WTRU-oriented selection of RACH-types based on TA prediction capability. If the WTRU does not predict the timing advance, the WTRU may use the first set of configurations for RACH transmission, for example, with TA = 0. The WTRU may determine to use 2-step or 4-step RACH based on first (legacy) set of configurations.

[0186] If the WTRU can predict the timing advance, the WTRU may perform TA prediction. If the WTRU can predict the timing advance, the WTRU may determine the accuracy of the predicted TA based on one or more of: received time stamps, the WTRU’s location / position within the cell, the WTRU’s mobility state, apredictive model (e.g., where the model also provides prediction accuracy as an output), and / or one or more measurements. If the accuracy of the predicted TA is low (e.g., below a threshold value) or determined to be invalid, the WTRU may use the first set of configurations for RACH transmission (e.g., with TA=0). The WTRU may determine to use 2-step or 4-step RACH using first (legacy) set of configurations. For example, if the accuracy of the predicted TA is low (e.g., below a threshold value) or determined to be invalid, the WTRU may transmit the preamble in Msg1 using TA=0 and the configured first set of resources. If the accuracy of the predicted TA is low (e.g., below a threshold value) or determined to be invalid, the WTRU may report that the accuracy of the predicted TA is low and / or the predicted TA to gNB.

[0187] If the accuracy of the predicted TA is high (e.g., higher than a threshold value) or determined to be valid, and if the measured RSRP is higher than the configured second MsgA RSRP threshold, the WTRU may determine to use two-step RACH (e.g., using the second set of configuration information). For example, if the accuracy of the predicted TA is high (e.g., higher than a threshold value) or determined to be valid, and if the measured RSRP is higher than the configured second MsgA RSRP threshold, the WTRU may use the configured second set of resources that correspond to 2-step RACH. If the accuracy of the predicted TA is high (e.g., higher than a threshold value) or determined to be valid, and if the measured RSRP is higher than the configured second MsgA RSRP threshold, the WTRU may transmit the preamble and PUSCH in MsgA using the predicted TA and the second set of resources. If the accuracy of the predicted TA is high (e.g., higher than a threshold value) or determined to be valid, and if the measured RSRP is higher than the configured second MsgA RSRP threshold, the WTRU may start, or restart TAT based on the configured second TAT.

[0188] If the accuracy of the predicted TA is high (e.g., higher than a threshold value) or determined to be valid, and if the measured RSRP is lower than the configured second MsgA RSRP threshold, the WTRU may determine to use 4-step RACH. For example, if the accuracy of the predicted TA is high (e.g., higher than a threshold value) or determined to be valid, and if the measured RSRP is lower than the configured second MsgA RSRP threshold, the WTRU may transmit the preamble in Msg1 using the predicted TA and the configured second set of resources. If the accuracy of the predicted TA is high (e.g., higher than a threshold value) or determined to be valid, and if the measured RSRP is lower than the configured second MsgA RSRP threshold, the WTRU may report the measured RSRP and the reason that WTRU determined to select 4-Step RACH (e.g., as part of Msg3). If the accuracy of the predicted TA is high (e.g., higher thana threshold value) or determined to be valid, and if the measured RSRP is lower than the configured second MsgA RSRP threshold, the WTRU may start, or restart TAT based on the configured second TAT.

[0189] The WTRU may monitor to receive RAR within the configured RAR window.

[0190] One or more WTRU-oriented selection of configurations for RACH transmission may be implemented. A WTRU may receive and / or detect a physical broadcast channel (PBCH) from a cell (e.g., during initial access, random access, etc.). The PBCH may carry system information. The PBCH may include or carry a master information block (MIB). The term MIB may be used to represent the content, information, payload, and / or bits carried by the PBCH. PBCH and MIB may be used interchangeably herein. The PBCH may be part of an SS / PBCH block (SSB). The PBCH may include one or more information bits to detect the CORESET#0 and common search space (CSS) to (monitor to) find the first system information block (SIB) (e.g., SIB1). The SIB1 may include information content to monitor and detect other SIBs. The WTRU may receive one or more configuration information via SIBs. For example, the WTRU may receive configuration information to be used for RACH configuration.

[0191] In another example, the random-access procedure may be initiated by a PDCCH order, by the MAC entity itself, or by RRC, for example based on one or more events. For example, the WTRU may receive one or more configuration information regarding the RA procedure via RRC, MAC-CE, DCI, etc. signaling and / or indications.

[0192] In an example, the RACH configuration may include one or more of the following configurations. For example, the RACH configuration may include time and frequency resources to be used for RACH transmission. The RACH configuration may include number of preambles, preamble types, preambles’ root sequence index, etc. to be used for generating preambles for RACH transmission. The RACH configuration may include contention-based or contention-free RACH, for example configured via RACH- ConfigDedicated to indicate the dedicated random-access parameters. The RACH configuration may include random access type, for example the WTRU may determine or be configured to transmit PRACH based on Type-1 or Type-2 random access procedures, that is 4-step or 2-step RACH, respectively. The RACH configuration may include random-access response (RAR) configurations, for example, configured via ra-ResponseWindow or msgB-ResponseWindow, for 4-step or 2-step RACH procedures, respectively.

[0193] Four-Step RACH and / or 2-Step RACH may be implemented. In an example, a WTRU may receive one or more configuration information and / or conditions to use 4-step and / or 2-step RACH. In an example, in case the WTRU may determine or be configured to use the 4-step RA, the WTRU may transmit a configured, selected, and / or determined PRACH preamble to the cell. After sending the PRACH preamble,the WTRLI may monitor for a DL message (e.g., PDCCH). For example, the DL message may indicate an RAR message that may provide an UL grant. As such, the WTRU may send an UL message or indication (e.g., in a PUSCH) based on the UL grant.

[0194] In another example, in case the WTRU may determine or be configured to use the 2-step RA, the WTRU may transmit a MsgA that may include a configured, selected, and / or determined PRACH preamble, and a PUSCH carrying a message to the cell. After sending MsgA, the WTRU may monitor for a DL message (e.g., PDCCH). For example, the DL message may indicate a MsgB that may include, for example at least, an RAR and may include contention resolution information.

[0195] In an example, the WTRU may be configured to perform RA procedure based on 4-step RACH. In another example, the WTRU may be configured to perform RA procedure based on 2-step RACH. In another example, both 4-step and 2-step RACH may be configured for the active BWP. The WTRU may consider one or more conditions to select from 4-step and 2-step RACH. For example, the WTRU may be configured with one or more thresholds on one or more parameters to select performing between 4-step or 2-step RACH procedures. In an example, the WTRU may select the 2-step RACH, if the measured RSRP based on the selected SSB is higher than a configured threshold (e.g., MsgA-RSRP-Threshold).

[0196] If a WTRU is configured and / or determines to operate based on 2-step RACH, the WTRU may be configured or receive one or more configuration information (e.g., via RACH-ConfigCommonTwoStepRA, MsgA-PUSCH-Config, etc.) (e.g., via SIB, RRC, MAC-CE, and / or DCI, etc.). The configurations may include but not limited to one or more of the following.

[0197] MsgA PUSCH resource configurations are described. For example, the WTRU may be configured with one or more configuration information on the time and frequency resources to be used for transmission of the MsgA PUSCH. In an example, the WTRU may be configured with one or more of the following.

[0198] The WTRU may be configured with slot information. For example, the WTRU may be configured with the number of slots containing one or more of the PUSCH occasions (PC) (e.g., via nrofSIotsMsgA- PUSCH), where the slots may be in the active UL BWP numerology, and each slot may have the same time domain resources allocation. In addition, in an example, the WTRU may be configured with the number of time domain PCs in each slot (e.g., via nrofMsgA-PO-PerSlot), where the configured PCs including corresponding guard periods may be contiguous in time domain within a slot.

[0199] The WTRU may be configured with time domain configurations. In an example, the WTRU may be configured with a combination of start symbol, length, and PUSCH mapping type (e.g., via msgA-PUSCH- TimeDomainAllocation). In another example, the WTRU may be configured with an index indication thatmay indicate a combination of start symbol, length, and PUSCH mapping type (e.g., via stai SymbolAndLengthMsgA, mappingTypeMsgA, etc.). In another example, the WTRU may be configured with a time offset with respect to the start of an associated PRACH slot (e.g., with at least one valid RO), counted as the number of slots, that may be based on the numerology of active UL BWP (e.g., via msgA- PUSCH-TimeDomainOffset). Moreover, the WTRU may be configured with guard period between PUSCH occasions in the unit of symbols (e.g., via guardPeriodMsgA-PUSCH).

[0200] The WTRU may be configured with frequency domain configurations. In an example, the WTRU may be configured with the offset of lowest PUSCH occasion in frequency domain with respect to PRB 0 (e.g., via frequencyStartMsgA-PUSCH). In another example, the WTRU may be configured with number of msgA PUSCH occasions FDMed in one time instance (e.g., via nrofMsgA-PO-FDM), and / or the number of PRBs per PC (e.g., v / a nrofPRBs-PerMsgA-PO). Moreover, the WTRU may be configured with PRB-level guard band between FDMed PUSCH occasions (e.g., via guardBandMsgA-PUSCH).

[0201] The WTRU may be configured with other information. For example, the WTRU may be configured with Msg A PUSCH MCS (e.g., via msgA-MCS), Msg A PUSCH frequency hopping configuration (e.g., via msgA-lntraSlotFrequencyHopping, msgA-HoppingBits, etc.), MsgA PUSCH DMRS configuration (e.g., via msgA-DMRS-Config, nrofDMRS-Sequences, msgA-DMRS-AdditionalPosition, msgA-MaxLength, msgA- PUSCH-DMRS-CDM-Group, etc.).

[0202] RACH occasions configuration may be implemented. In an example, a WTRU may receive, identify, or be configured the time domain resource allocations for the consecutive RACH occasions (RO) based on the higher-layer parameter prach-Configurationlndex, or by msgA-PRACH-Configurationlndex if configured. These parameters denote the PRACH configuration index corresponding to tables that include random access parameters. One or more of the following parameters may be derived from the table: preamble format, frame number and slot number, starting symbol, number of PRACH slots, number of timedomain PRACH occasions, and / or PRACH duration.

[0203] Preamble format may refer to one of the possible formats (e.g., namely: A1, A2, A3, B1 , A1 / B1 , A2 / B2, A3 / B3, B4, CO, C2). The preamble format may identify the corresponding Cyclic Prefix (CP) duration, sequence part duration, and guard time duration (if applicable). Frame number and slot number may indicate the frames that may be used for the PRACH transmission and the PRACH slot within the corresponding frame. The starting symbol may determine the symbol-level index corresponding to the starting position of the first RO transmission within the PRACH slot. The number of PRACH slots within a 60 kHz slot may define the number of PRACH slots within the reference PRACH slot (e.g., for higher SCSsuch as 120kHz, 480kHz, 960kHz), considering the 60kHz PRACH slot as the reference slot. The number of time-domain PRACH occasions within a PRACH slot (j\iRA’slot)may define the number of consecutive ROs that are located within a PRACH slot in time domain. PRACH duration may correspond to the preamble format implying the number of sequence part within an RO.

[0204] The WTRU may receive the frequency domain resource allocations for the ROs based on msg1- FrequencyStart or msgA-RO-FrequencyStart and / or msg1-FDM or msgA-RO-FDM. msg1 -Frequencystart or msgA-RO-FrequencyStart if configured, indicates the offset of the lowest PRACH transmission occasion in frequency domain with respect to the PRB 0.

[0205] msg1-FDM or msgA-RO-FDM if configured, indicates the number of PRACH transmission occasions that are FDMed in one time-domain RO. The WTRU may receive, identify, and / or be configured the number of ROs in frequency domain (M) per each time-domain PRACH occasion based on the higher parameter msg1-FDM, msg1-FDM-16, or msgA-RO-FDM if configured, msg1-FDM={one, two, four, eight}. The WTRU may number the PRACH frequency resources nRA={0, 1,...,M-1}, starting from the lowest frequency, in increasing order in the initial uplink BWP during the initial access or the active uplink BWP otherwise.

[0206] The WTRU may receive the association and mapping between the SS / PBCH block indexes and PRACH transmission occasions based on higher layer parameter (e.g., ssb-perRACH-OccasionAndCB- PreamblesPerSSB = {1 / 8, 1 / 4, 1 / 2, 1,2, 4, 8, 16}). The parameter may indicate the number of SS / PBCH block indexes associated with a PRACH transmission occasion in addition to the number of preambles per SS / PBCH block index per PRACH occasion.

[0207] Configurations for RACH transmission for WTRUs with WTRU-sided TA determination may be implemented. A WTRU does one or more of the following. For example, the WTRU may detect and / or receive one or more SSB indexes during initial and / or random access and measures corresponding RSRP values. The WTRU may determine or receive triggers to perform RACH procedure associated with one of the SSB indexes (e.g., with the highest RSRP, indicated via PDCCH order, based on BFR configs., etc.).

[0208] In configurations of a WTRU, the WTRU may receive one or more configuration information regarding WTRU-sided Timing Advance (TA) determination, for example including a flag indication (e.g., via SIB, RRC, MAC-CE, DCI) that allows and / or enables TA prediction for capable WTRUs.

[0209] In configurations of a WTRU, if WTRU-sided TA determination is allowed and / or enabled, the WTRU may receive a first (e.g., legacy) and a second set of configurations for RACH transmission (e.g., via MIB, SIB, RRC, MAC-CE, DCI, etc.). If WTRU-sided TA determination is allowed and / or enabled, thefirst / second set of configurations may include any combination of: a first and / or second set of RACH time and frequency resources, first and / or second set of preambles (e.g., such that the second set has more number of preambles than the first set), first and / or second RACH configs (e.g., where the second RACH config has shortened guard bands and guard time), first and / or second preamble formats (e.g., where the second preamble format has short preambles), first and / or second timeAlignmentTimer (TAT) value (e.g., where the second TAT value is longer), etc. If WTRU-sided TA determination is allowed and / or enabled, the first and / or second set of configurations may include first and / or second MsgA configs for 2-step RACH, which may include any combination of: first and / or second PUSCH time and freq, resources, first and / or second PUSCH mapping type, first and / or second PUSCH starting symbol S (e.g., non-zero S), first and / or second PUSCH length L (e.g., second PUSCH length is shorter than first PUSCH length), first and / or second PUSCH MCS (e.g., second MCS is higher than first MCS), first and / or second MsgA RSRP threshold (e.g., second RSRP threshold is lower than first (e.g., legacy) RSRP threshold), etc.

[0210] In an embodiment, a WTRU may detect and / or receive one or more SSBs, where the WTRU may measure one or more parameters based on the received SSBs. For example, the WTRU may measure RSRP, RSRQ, SINR, etc. based on the received and / or detected SSBs. In an example, the WTRU may receive and / or determine one or more SSB indexes corresponding to the detected and / or received SSBs.

[0211] In an example, the WTRU may determine to perform a RACH procedure based on one or more of the received, detected, and / or measured SSBs. For example, the WTRU may determine to perform the RACH procedure based on the SSB with the highest measured RSRP during initial access, cell (re)selection, etc. In another example, the WTRU may determine to perform RACH procedure based on one or more of the received, detected, and / or measured SSBs based on one or more events and / or triggers. For example, the WTRU may receive the triggers via higher layers. In an example, the WTRU may determine to perform the RACH procedure due to beam failure detection event and as part of beam failure recovery. In another example, the WTRU may receive one or more indications (e.g., from a gNB) to perform the RACH procedure based on one or more received, detected, and / or measured SSBs. For example, the WTRU may receive a PDCCH ordered (e.g., via MAC-CE, DCI, etc.) to perform RACH procedure based on one or more indicated, configured, and / or determined SSBs.

[0212] In an embodiment, the WTRU may be configured and / or receive one or more configuration information and / or indication signaling from one or more cells, on whether the WTRU may operate based on a first or a second mode of operation. The WTRU may be configured with the first and the second modes of operation regarding UL transmission based on WTRU-sided determined and / or predicted TA.

[0213] In an example, the first mode of operation may indicate that the operation and / or UL transmission based on WTRU-sided determined and / or predicted TA is not allowed, disabled, and / or not supported in the corresponding cells. In another example, the second mode of operation may indicate that the operation and / or UL transmission based on WTRU-sided determined and / or predicted TA is allowed, enabled, and / or supported in the corresponding cells.

[0214] In an example, the WTRU may determine the mode of the operation in the cell based on an implicit indication and / or explicit indication. When an implicit indication applies, the WTRU may determine the mode of the operation in the cell based on that Sync Raster. For example, the WTRU may implicitly determine the mode of operation of the cell based on the sync raster corresponding to the received and / or detected SSB. In an example, one or more Sync raster sets may be used, defined, configured, or determined and each of Sync raster sets may be a subset of a channel raster. A sync raster set may be mutually exclusive to another sync raster set.

[0215] When implicit indication applies, the WTRU may determine the mode of the operation in the cell based on that the WTRU may determine that the cell operates in the first mode of operation (e.g., without WTRU-sided TA prediction), if the sync raster corresponding to the received and / or detected SSB is in a first sync raster set. The WTRU may determine that the cell operates in the second mode of operation (e.g., with WTRU-sided TA prediction), if the sync raster corresponding to the received and / or detected SSB is in a second sync raster set, etc.

[0216] When an explicit indication applies, the WTRU may determine the mode of the operation in the cell based on that MIB. In an example, the WTRU may receive an explicit indication in MIB indicating the mode of operation for the cell.

[0217] When an explicit indication applies, the WTRU may determine the mode of the operation in the cell based on that SIB. In an example, the WTRU may receive an explicit indication in SIB (e.g., SIB1 , SIB2, etc.) that indicates the mode of operation for the cell. In an example, the WTRU may blindly detect the CORESET#0 and TypeO-PDCCH CSS based on the different interpretation of the MIB parameters for different modes of operation, when explicit signaling of the mode of operation is not present or cannot be decoded from MIB. The WTRU may blindly determine the mode of operation to be without WTRU-sided TA prediction and attempt to detect the CORESET#0 and TypeO-PDCCH CSS based on the received MIB parameters (e.g., in a first set of time and frequency resources). Alternatively, the WTRU may blindly determine the mode of operation to be with WTRU-sided TA prediction and attempt to detect theCORESET#0 and TypeO-PDCCH CSS based on the received MIB parameters (e.g., in a second set of time and frequency resources).

[0218] When an explicit indication applies, the WTRU may determine the mode of the operation in the cell based on that flag indication. In an example, the WTRU may receive an indication via a flag indication, for example via RRC, MAC-CE, DCI, etc. For example, the flag indication with a first value (e.g., value one) may indicate the first mode of operation (e.g., without WTRU-sided TA prediction) and the flag indication with a second value (e.g., value zero) may indicate the second mode of operation (e.g., with WTRU-sided TA prediction).

[0219] Configurations sets based on configured modes of operation may be implemented. As an embodiment, a WTRU may determine, be (pre)configured, and / or receive one or more signalling on a first and a second set of configurations for performing RACH procedures, in case the WTRU may operate based on the first or second modes of operation, respectively. For example, the WTRU may receive the first and second sets of configuration information via MIB, SIB, RRC, MAC-CE, DCI, etc. In an example, the first and second sets of configuration information may include one or more configurations for RACH procedure, as described in foregoing WTRU-oriented selection of configs for RACH transmission.

[0220] In an example, the first and second sets of configurations may differ based on one or more of the following: time and frequency resources for RACH transmission, preambles resources, guard bands and guard time, preamble formats, timers, MsgA configuration for 2-step RACH.

[0221] For example, the second set of time and / or frequency resources may be overlapping, partially overlapping, or non-overlapping with the first set of time and frequency resources. For example, the second set of preamble resources may be different from the first set of preamble resources, where the second set of preamble resources may include higher number of preamble resources compared to the first set of preamble resources. For example, the second configured and / or determined guard bands and / or guard times may be shorter compared to the first configured guard bands and / or guard times, respectively. For example, the second configured preamble formats may indicate shorter preambles and / or shorter preamble formats, compared to the first configured preambles and / or preamble formats, respectively. For example, the WTRU may determine or be configured with one or more second timeAlignmentTimer values (TAT), where the second TATs may be longer than the first configured TATs.

[0222] For example, the second MsgA configuration may include, second PUSCH time and frequency resource configurations, second PUSCH mapping type, second PUSCH starting symbol that may be for example a non-zero value, second PUSCH length that may be for example shorter than the first configuredPUSCH length, second PUSCH MCS that may be for example higher than the first configured MCS, second MsgA RSRP threshold that may be lower than the first configured RSRP threshold), etc.

[0223] In an example, in case the WTRU may determines, is (pre)configured and / or receives configuration or indication to operate based on the first mode of operation, the WTRU may transmit the RACH messages based on the first configured set of configurations. In an example, in case the first mode of operation indicates operation without WTRU-sided TA prediction, the WTRU may send the RACH messages with TA equal to zero. For instance, the WTRU may not apply a TA for the transmission of the RACH messages. In another example, the WTRU may be configured with a non-zero TA, where the WTRU may use the configured TA for the transmission of the RACH messages. In an example, the WTRU may send RACH messages, including for example Msg1, Msg3, MsgA, etc.

[0224] In an example, in case a WTRU may determine, is (pre)configured, and / or receives configuration or indication to operate based on the second mode of operation, the WTRU may transmit the RACH messages based on the second configured set of configurations.

[0225] In an example, a WTRU may determine or be configured with WTRU-sided TA prediction and / or determination. In an example, the WTRU may perform the TA prediction and / or determination based on one or more of received and / or detected SSBs, DL RSs, etc. For example, the WTRU may perform the TA prediction based on one or more methodologies. Some examples are addressed in the common solution components: UL timing adjustment estimation / prediction section herein.

[0226] In an example, in case the second mode of operation indicates operation with WTRU-sided TA prediction, the WTRU may send the RACH messages based on the WTRU-sided determined and / or predicted TA. The WTRU may apply the predicted and / or determined TA for the transmission of the RACH messages. In an example, the WTRU may send RACH messages, including for example Msg1 , Msg3, MsgA, etc.

[0227] Examples of WTRU-oriented selection of RACH-types based on TA prediction capability may be implemented. For example, if WTRU cannot predict the timing advance, the WTRU may use the first set of configurations for RACH transmission, with TA = 0. The WTRU may determine to use 2-step or 4-step RACH based on first (e.g., legacy) set of configurations.

[0228] If WTRU can predict the timing advance, the WTRU may perform TA prediction. The WTRU may determine the accuracy of the predicted TA based on one or more of: received time stamps, WTRU’s location / position within the cell, WTRU’s mobility, predictive model (e.g., where the model also provides prediction accuracy as an output), or the measurements.

[0229] If the accuracy of the predicted TA is low (e.g., below a threshold value) or determined to be invalid, the WTRU may use the first set of configurations for RACH transmission, with TA=0. The WTRU may determine to use 2-step or 4-step RACH using first (legacy) set of configurations. The WTRU may transmit the preamble in Msg1 using TA=0 and the configured first set of resources. The WTRU may report that the accuracy of the predicted TA is low and / or the predicted TA to gNB.

[0230] If the accuracy of the predicted TA is high (e.g., higher than a threshold value) or determined to be valid, and if the measured RSRP is higher than the configured second MsgA RSRP threshold, the WTRU may determine to use two-step RACH. The WTRU may use the configured second set of resources that correspond to 2-step RACH. The WTRU may transmit the preamble and PUSCH in MsgA using the predicted TA and the second set of resources. The WTRU may start, or restart TAT based on the configured second TAT.

[0231] If the accuracy of the predicted TA is high (e.g., higher than a threshold value) and / or determined to be valid, and if the measured RSRP is lower than the configured second MsgA RSRP threshold, the WTRU determines to use 4-step RACH. The WTRU may transmit the preamble in Msg1 using the predicted TA and the configured second set of resources. The WTRU may report the measured RSRP and the reason that WTRU might determine to select 4-Step RACH (e.g., as part of Msg3). The WTRU may start, or restart TAT based on the configured second TAT.

[0232] In some examples, the WTRU may monitor to receive RAR within the configured RAR window.

[0233] Examples of legacy WTRUs and / or WTRUs incapable of WTRU-sided TA prediction and / or determination may be implemented. A WTRU that is not capable of predicting and / or determining WTRU- sided TA may use the first configured set of configurations for RACH transmission. In an example, a legacy WTRU that is not capable of WTRU-sided TA prediction and / or determination may use the legacy set of RACH configurations that may be based on first set of RACH configurations.

[0234] For example, if the WTRU is configured with both 2-step and 4-step RACH, the WTRU may determine to use 2-step RACH or 4-step RACH based on the first set of configurations for RACH transmission. In an example, the WTRU may measure RSRP of one or more selected and / or determined SSBs. For example, the WTRU may select and / or determine the SSBs based on a configuration, a received indication, and / or for example based on the SSB with the highest RSRP. The WTRU may determine to perform the RACH procedure based on 2-step RACH for the selected and / or determined SSBs if the measured RSRP is higher than the first configured MsgA RSRP threshold. The WTRU maydetermine to use 4-step RACH procedures if the measured RSRP is lower than the first configured MsgA RSRP threshold.

[0235] Examples of WTRUs capable of WTRU-sided TA prediction and / or determination may be implemented. A WTRU that is capable of predicting and / or determining WTRU-sided TA may perform WTRU-sided TA prediction and / or determination, where the WTRU may determine the accuracy of the predicted and / or determined TA.

[0236] The WTRU may determine the accuracy of the WTRU-sided TA prediction. For example, if the WTRU determines that the accuracy of the WTRU-sided TA prediction is not valid, the WTRU may determine to use the first set of configurations for RACH transmission. In an example, the WTRU that has determined that the accuracy of the predicted and / or determined TA is invalid may perform fall-back and use the legacy set of RACH configurations that may be based on the first set of RACH configurations, for example with zero TA. In an example, the WTRU that may be configured with both 2-step and 4-step RACH procedures may determine to use 2-step RACH or 4-step RACH based on the measured RSRP of the selected SSB and the first configured MsgA RSRP threshold, as described herein.

[0237] As an embodiment, for example, a WTRU may determine or be configured to report the invalid accuracy of the TA prediction, for example to a gNB. For example, the WTRU may indicate to the gNB that the WTRU may have the WTRU-capability to perform the TA prediction; however, the prediction accuracy is invalid. In an example, the WTRU may have already indicated the WTRU-capability to perform TA prediction and / or determination as part of WTRU-capability report. As such, the WTRU may indicate the invalid or unacceptable accuracy of the TA prediction via a separate indication, for example a flag indication. For example, the WTRU may indicate the valid or acceptable accuracy of TA prediction via a first value for the flag indication (e.g., value one), or the WTRU may indicate the invalid or inacceptable accuracy of the TA prediction via a second value for the flag indication (e.g., value zero). In another example, the WTRU may indicate WTRU-capability to perform TA prediction and / or determination, the accuracy of the TA prediction, and one or more other corresponding parameters via one or more indications as part of the report. In an example, the WTRU may send the report as part of RACH procedure, e.g., via MsgA, Msg3, etc. In another example, the WTRU may send the report after switching to RRC-Connected mode, for example as part of UCI, MAC-CE, etc. The WTRU may determine and / or be configured to report the determined and / or predicted TA as part of the transmitted report.

[0238] If a WTRU determines that the accuracy of the WTRU-sided TA prediction is valid and / or acceptable, the WTRU may determine to use the second set of configurations for RACH transmission. Inan example, the WTRU may use the second configured time and frequency resources for RACH transmission, where the WTRU may use the predicted and / or determined TA, that may be for example nonzero TA, for the transmission of UL RACH messages (e.g., PRACH preamble, Msg1 , MsgA, Msg3, etc.). In another example, the WTRU that is configured with both 2-step and 4-step RACH procedures may determine to use 2-step RACH or 4-step RACH based on the measured RSRP of the selected SSB and the second configured MsgA RSRP threshold, as described herein. In another example, the WTRU may transmit the PRACH preamble, based on the second configured set of preamble resources and second configured preamble formats.

[0239] In case the WTRU has determined to use 2-Step RACH, the WTRU may send the PUSCH in MsgA based on the predicted TA and the second MsgA configurations. In case the WTRU has determined to use 4-step RACH, the WTRU may determine or be configured to report the measured RSRP and / or indicate the reason for selecting 4-Step RACH. In an example, the WTRU may report the measured RSRP as part of Msg3. In another example, the WTRU may report the measured RSRP as part of an upcoming scheduled and / or configured CSI-RS report, PUCCH, PUSCH, etc.

[0240] In some examples, if a WTRU that is performing TA prediction and / or determination determines that the TA predictions accuracy is valid and / or acceptable, the WTRU may start, initiate, and / or restart TAT based on the second configured TAT. In an example, the WTRU may start, initiate, and / or restart TAT based on the second configured TAT after predicting TA, determining TA, and / or reporting the TA. In an example, the second configured TAT may be extended or longer than the first determined and / or (pre)configured TAT value. Otherwise, if the WTRU determines that the TA prediction accuracy is not valid or is unacceptable, the WTRU may use the first configured TAT.

[0241] In some examples, the WTRU that has transmitted RACH may monitor to receive RAR within a determined and / or configured time period.

[0242] The WTRU may be configured with various RAR configurations in systems with WTRU-sided TA determination. A WTRU with TA-prediction capabilities may be configured with a first set of Random Access configurations and a second set of Random Access configurations (e.g., configured only for WTRUs with TA-prediction capabilities). The WTRU with TA prediction capabilities may determine predicted TA during RA based on a determined (e.g., best) SSB.

[0243] The WTRU may send the RACH messages (e.g., Msg1 or Msg A) based on the predicted TA and a second set of resources and / or based on a second set of configurations that are configured for WTRUs with TA-prediction capabilities. The WTRU may be configured to report the predicted TA in MsgA PUSCHin case of 2-Step RACH. The WTRLI may monitor to receive RAR within the configured RAR window. The WTRU may monitor to receive RAR in a second set of resources that is configured for WTRUs with TA- prediction capabilities. The WTRU may monitor to receive RAR based on a second RA_RNTI that is configured for WTRUs with TA-prediction capabilities.

[0244] In case RAR is received, the WTRU may receive one or more indications that are configured for WTRUs with TA-prediction capabilities. The WTRU may receive an indication to enable and / or disable TA prediction and / or an indication on a Timing Advance Command (TAC) Type. The WTRU may receive indication to deactivate TA prediction, or to perform model updating and / or training (e.g., the gNB may detect the PRACH / MsgA and determine that the used TA is not valid and / or is not acceptable). The WTRU may receive indication of whether the TAC is short, indicating that the TAC includes TA adjustment and not the absolute TA. Or, that the TAC is long, indicating that the TAC includes absolute value TA. For example, in case the received RAR is a short format the WTRU uses the received TA adjustment to update the predicted TA for determining a second UL TA. For example, in case the received RAR is a long format, the WTRU may be configured (e.g., preconfigured or as part of RAR PDSCH) with one or more configurations. For example, in one configuration, the WTRU may use the indicated absolute value TAC for determining a second UL TA. For instance, this may implicitly indicate to deactivate the WTRU-sided TA determination. In another example, the WTRU may use the indicated absolute value TAC in addition to the predicted TA for determining a second UL TA.

[0245] In some examples, if RAR is received, in case of 2-step RACH and reception of fall back RAR, or in case of 4-step RACH, the WTRU may use the determined second UL TA for Msg3 (e.g., configured PUSCH) transmission. Where 2-step RACH fallback RAR may be received by the WTRU for cases where the gNB received PRACH but not Msg A PUSCH. A fallback RAR includes resources for PUSCH retransmission, for which transmission the WTRU may use the determined second UL TA.

[0246] In some examples, if RAR is received, the WTRU may be configured to report the predicted TA and / or the determined second UL TA as part of Msg3.

[0247] In an embodiment, a WTRU may determine and / or be configured to operate based on a first and / or second modes of operation with regards to timing advance and / or timing adjustments for one or more UL transmissions. In an example, the WTRU may operate based on the first mode of operation that is without WTRU-sided TA prediction and / or determination. In another example, the WTRU may operate based on the second mode of operation that is with WTRU-sided TA prediction and / or determination.

[0248] For example, the WTRLI may determine and / or be configured to perform WTRU-sided TA prediction and / or determination. For example, the WTRU may perform the TA prediction and / or determination based on one or more received, detected, and / or measured SSBs, DL RSs, etc. The WTRU may perform the TA prediction based on one or more methodologies.

[0249] In an example, the WTRU may receive, determine, and / or be configured with a first and a second set of configurations for operation in the first or second modes of operation, respectively. For example, the WTRU may receive, determine, and / or be configured with a first and a second set of configurations for one or more UL transmissions, including for example RACH transmissions.

[0250] In an example, a WTRU may determine and / or be configured to operate based on second mode of operation, where the WTRU may receive and / or be (pre)configured with one or more second configuration information and / or indications. For example, the WTRU may use the second set of configurations for UL transmissions based on predicted and / or determined TA values. For example, the WTRU may transmit one or more RACH messages based on predicted and / or determined TA values using the second set of configurations. In another example, the WTRU may transmit PRACH preamble in Msg1 (e.g., for 4-step RACH), MsgA PRACH, MsgA PUSCH (e.g., for 2-step RACH), and / or so forth, based on second set of configurations. For example, the second set of configurations may include second set of time and frequency resources for RACH transmission, second type of preambles, etc.

[0251] In some examples, a WTRU may determine, be configured, and / or receive configuration to report the predicted and / or determined TA. For example, the WTRU may receive the configuration, for example via MIB, SIB, RRC, MAC-CE, DCI, etc. In an example, the WTRU may determine or be configured to report the predicted and / or determined TA as part of the MsgA PUSCH, in case the WTRU performs 2-step RACH.

[0252] In some examples, a WTRU may select and / or transmit PRACH preamble based on a first or a second set of preambles based on the selected mode of operation. In an example, the WTRU may select and transmit PRACH preamble based on the first configured set of preambles if the selected and / or active mode of operation is based on the first mode of operation (e.g., without WTRU-sided TA prediction and / or determination). In another example, the WTRU may select and transmit PRACH preamble based on the second configured set of preambles if the selected and / or active mode of operation is based on the second mode of operation (e.g., with WTRU-sided TA prediction and / or determination).

[0253] Examples of random-access response (RAR) reception based on active mode of operation may be implemented. After transmission of an RO (e.g., Msg1 in 2-step RACH) and / or a PO (e.g., MsgA in 4-stepRACH), the WTRU may monitor and attempt to detect the random-access response (RAR) message within the period of an RAR-window or limit. In an example, in 4-step RACH, the WTRU may monitor and attempt to detect and / or receive one or more DL signaling (e.g., via DCI) with CRC scrambled with RA-RNTI. In another example, in 2-step RACH, the WTRU may monitor and attempt to detect and / or receive MsgB that includes RAR in addition to contention resolution identity. For example, in 2-step RACH, the WTRU may attempt to detect a DL signaling (e.g., via DCI) with CRC scrambled with MsgB-RNTI or C-RNTI.

[0254] In some examples, a WTRU may monitor and attempt to detect and / or receive a RAR based on a first or second set configurations based on the selected and / or active mode of operation. In an example, the WTRU may attempt to detect RAR based on the first set of configurations if the WTRU has selected the first mode of operation (e.g., without WTRU-sided TA prediction and / or determination) as active mode of operation. In another example, the WTRU may attempt to detect RAR based on the second set of configurations if the WTRU has selected the second mode of operation (e.g., with WTRU-sided TA prediction and / or determination) as active mode of operation. In an example, the WTRU may receive one or more configuration information on the first and second sets of configurations, for example, via MIB, SIB, RRC, MAC-CE, and / or DCI, etc. For example, one or more of the following may be included in the first and / or second RAR configuration sets.

[0255] For example, time and frequency resources may be included in the first and / or second RAR configuration sets. For example, the WTRU may monitor and attempt to receive RAR based on a first set of time and frequency resources (e.g., first CORESET resources) if the WTRU operates based on the first mode of operation (e.g., without WTRU-sided TA prediction and / or determination). In another example, the WTRU may monitor and / or attempt to receive RAR based on a second set of time and frequency resources (e.g., second CORESET resources) if the WTRU operates based on the second mode of operation (e.g., with WTRU-sided TA prediction and / or determination).

[0256] RNTI may be included in the first and / or second RAR configuration sets. For example, the WTRU may monitor and attempt to receive RAR via DCI with CRC scrambled with a first RNTI value (e.g., first RA- RNTI for 4-step RACH, first MsgB-RNTI for 2-step RACH, etc.) if the selected and / or active mode of operation is based on the first mode of operation (e.g., without WTRU-sided TA prediction and / or determination). In another example, the WTRU may monitor and / or attempt to receive RAR via DCI with CRC scrambled with a second RNTI value (e.g., second RA-RNTI for 4-step RACH, second MsgB-RNTI for 2-step RACH, etc.) if the selected and / or active mode of operation is based on the second mode of operation (e.g., with WTRU-sided TA prediction and / or determination).

[0257] RAR time window may be included in the first and / or second RAR configuration sets. For example, the WTRU may monitor and attempt to receive RAR based on a first time limit and / or first time window if the selected and / or active mode of operation is based on the first mode of operation (e.g., without WTRU- sided TA prediction and / or determination). In another example, the WTRU may monitor and / or attempt to receive RAR based on a second time limit and / or second time window if the selected and / or active mode of operation is based on the second mode of operation (e.g., with WTRU-sided TA prediction and / or determination).

[0258] The WTRU may determine the mode of operation based on the received RAR. In some examples, a WTRU may determine the mode of operation e.g., operation with and / or without WTRU-sided TA prediction) based on the received random-access response (RAR). One or more of the following may apply. For example, the WTRU may determine the mode of operation (e.g., operation with or without WTRU-sided TA prediction) based on the received random-access response (RAR) that RAR may indicate accepting, enabling, and / or allowing the second mode of operation.

[0259] For example, the WTRU may determine that the received RAR (e.g., received within the RAR reception time window or limit) may indicate that the NW and / or the cell, for example the gNB, has accepted the WTRU to perform WTRU-sided TA prediction and / or determination. The WTRU may transmit the determined and / or configured UL transmissions based on the WTRU-sided predicted and / or determined TA values.

[0260] In an example, the WTRU may determine that the received RAR message contains a Random- Access Preamble Identifier (RAPID) that matches the RAPID or preamble transmitted by the WTRU. The WTRU may receive the indication via RAR based on one or more of the following. For example, the WTRU may receive the indication via RAR based on implicit indication. Implicit indication may include, for example, reception of the RAR itself may indicate that the NW and / or cell (e.g., gNB) has accepted the WTRU to connect and / or camp on the cell, and that the active mode of operation may be the second mode of operation (e.g., with WTRU-sided TA prediction and / or determination).

[0261] Implicit indication may include, for example, reception of RAR in time and frequency resources corresponding to second mode of operation (e.g., second configured RAR time and frequency resources) may implicitly indicate that the NW and / or the cell, for example the gNB, has accepted the WTRU to camp on the cell, and that the active mode of operation may be second mode of operation (e.g., with WTRU- sided TA prediction and / or determination).

[0262] Implicit indication may include, for example, the WTRU may receive a RAR including an indication on whether the timing-advance command (TAC) in the RAR is a short or a long format. For example, if the TAC indicated via RAR is a short format, this means that TAC is only the adjustment value for TA (e.g., 6 bits). In another example, if the TAC indicated via RAR is a long format, the WTRU determines that the TAC may include absolute value of TA (e.g., 12 bits). As such, in case the RAR indication indicates that the RAR includes a short TAC, this may implicitly indicate that NW and / or cell, for example the g N B, has accepted the WTRU to camp on the cell, and that the active mode of operation may be second mode of operation (e.g., with WTRU-sided TA prediction and / or determination).

[0263] The WTRU may receive the indication via RAR based on an explicit indication. For example, the WTRU may receive an explicit indication (e.g., a flag indication) included in the RAR (message) or for example included in the DCI scheduling the PDSCH carrying the RAR. Using the explicit indication, the WTRU may determine that the gNB has accepted the WTRU to camp on the cell, and that the active mode of operation may be second mode of operation (e.g., with WTRU-sided TA prediction and / or determination).

[0264] The WTRU may determine the mode of operation (e.g., operation with or without WTRU-sided TA prediction) based on the received random-access response (RAR). For example, the WTRU may determine to fallback to the first mode of operation (e.g., legacy). For example, the WTRU may determine that the received RAR may indicate rejecting, disabling, and / or not allowing the second mode of operation. The WTRU may connect to the cell based on the first mode of operation. For example, the WTRU may transmit the configured and / or determined UL transmission without using the WTRU-sided TA prediction and / or determination.

[0265] For example, the WTRU may determine that the received RAR may indicate that the NW and / or cell, for example the gNB, has not accepted that the WTRU may operate with the second mode of operation. In an example, this may be due to inaccurate WTRU-sided TA determination and / or prediction, or due to a load-balancing purpose at the network side. The WTRU may receive the rejection signaling via one or more of the following.

[0266] In some examples, the WTRU may receive the rejection signaling via cell common rejection signaling. For example, the WTRU may determine that the received RAR includes one or more (pre)configured information content that may indicate the rejection signaling for the second mode of operation. The rejection signaling may be group-based rejection signaling or cell-common rejection indication. For example, the WTRU may receive a RAR based on a DCI, for which the CRC in the DCI is scrambled with a first RNTI, where for example the first RNTI may WTRU’s computed RA-RNTI that is forexample based on where and / or when the PRACH was transmitted. In some examples, the WTRU may receive a RAR based on a DCI, for which the CRC in the DCI is scrambled with a second RNTI, where the second RNTI may be a (pre)configured RNTI that may be associated with acceptance or rejection of the second mode of operation. For example, the WTRU may determine that the RAPID (e.g., the preamble index) included in the received RAR is based on a (pre)defined or (pre)configured value (e.g., value for index 0 or FFFF) and that the RAPID does not match the index of the preamble transmitted by the WTRU. The WTRU may determine that the received RAPID matches a (pre)configured preamble index and that it indicates a rejection signaling for the second mode of operation.

[0267] In some examples, the WTRU may receive the rejection signaling via WTRU-specific rejection signaling. For example, the WTRU may determine that the received RAR includes one or more (pre)configured information content that may indicate the rejection signaling for the second mode of operation. The rejection signaling may be a WTRU-specific rejection indication. For instance, the WTRU may receive a RAR, or another message based on a DCI, where the DCI is scrambled with a rejection RNTI (e.g., RJ-RNTI), that may be for example, a (pre)configured or pre-defined RNTI. The DCI, RAR, and / or another message may indicate the index of the preamble (e.g., RAPID) transmitted by the WTRU. The WTRU may determine that the message was intended for the WTRU, for example based on matching the received RAPID with the preamble index transmitted by the WTRU. As such, the WTRU may determine that the received signaling indicates a rejection signaling for the second mode of operation.

[0268] In some examples, the WTRU may receive rejection signaling and / or rejection indication based on an implicit indication and / or an explicit indication.

[0269] The WTRU may receive a rejection indication based on an implicit indication. In an example, reception of RAR in time and frequency resources corresponding to the first mode of operation (e.g., first configured RAR time and frequency resources) may implicitly indicate that the NW and / or the cell, for example the gNB, has not accepted the WTRU to operate based on the second mode of operation. For instance, the reception of RAR in the first set of time and frequency resources may implicitly indicate that the WTRU is only allowed to camp on and / or connect to the cell based on the first mode of operation (e.g., without WTRU-sided TA prediction and / or determination).

[0270] In some examples, the WTRU may receive a RAR including an indication on whether the timingadvance command (TAC) in the RAR is a short or a long format. For example, if the TAC indicated via RAR is a short format, this means that TAC is only the adjustment value for TA (e.g., 6 bits). In another example, if the TAC indicated via RAR is a long format, the WTRU determines that the TAC may include absolutevalue of TA (e.g., 12 bits). If the RAR indication indicates that the RAR includes a long TAC, this may implicitly indicate that NW and / or cell, for example the gNB, has not accepted the WTRU to operate based on the second mode of operation. For instance, the reception of RAR with long TAC format may implicitly indicate that the WTRU is only allowed to camp on and / or connect to the cell based on the first mode of operation (e.g., without WTRU-sided TA prediction and / or determination).

[0271] The WTRU may receive a rejection indication based on an explicit indication. For example, the WTRU may receive an indicator (e.g., a flag indication) that may be included in the RAR or included in the DCI scheduling the PDSCH carrying the RAR, when for example the received RAR includes a RAPID that matches the index of the preamble transmitted by the WTRU. For instance, the WTRU may determine that the received indication indicates a rejection signaling for the second mode of operation.

[0272] The WTRU may determine the mode of operation (e.g., operation with or without WTRU-sided TA prediction) based on the received random-access response (RAR) that indicates a short or long TAC. In an example, a WTRU may receive a confirmation, acceptance, and / or an enabling command, for example as part of the received RAR, to operate based on the second mode of operation. For example, the second mode of operation may be based on WTRU-sided TA prediction and / or determination, and UL transmission based on the WTRU-sided predicted and / or determined TA. In an example, the WTRU may receive an indication, for example as part of the received RAR, indicating on whether the timing advance command (TAC) is short, which implies the TAC includes TA adjustment and not the absolute TA. Or, that the TAC is long, which implies the TAC includes absolute value TA.

[0273] In an example, if the received RAR includes the indication on the short format TAC, the WTRU may use the received TA adjustment to update the predicted TA for determining the UL TA. If the received RAR includes the indication on the long format TAC, the WTRU may be configured with one or more options. For example, the WTRU may be (pre)configured or receive configurations as part of RAR PDSCH. In an example, the WTRU may be configured to use the indicated absolute TA value for determining the UL TA. In another example, the WTRU may be configured to use the indicated absolute TA value in addition to the predicted TA for determining the UL TA value.

[0274] The WTRU may determine the mode of operation (e.g., operation with or without WTRU-sided TA prediction) based on the received random-access response (RAR) using the determined UL TA for UL transmissions. After a WTRU receives a confirmation, acceptance, and / or an enabling command to operate based on the second mode of operation and determining the UL TA value, the WTRU may use the determined UL TA value for one or more UL transmissions. In an example, in case of 4-Step RACH, theWTRU may use the determined UL TA value for Msg3 transmission. In another example, in case of 2-Step RACH and in case the received RAR is the corresponding MsgB is a fall back RAR, the WTRU may use the determined UL TA value for configured PUSCH transmission. In an example, in 2-Step RACH, gNB may have received PRACH based on second resources but may have not received Msg A PUSCH. So, MsgB may be a fall back RAR, including the resources for PUSCH transmission, where WTRU may use the determined UL TA value for corresponding PUSCH transmission.

[0275] In some examples, the WTRU may determine and / or be configured to report the predicted TA and / or the determined UL TA as part of Msg3 and / or as part of the RAR configured PUSCH.

[0276] Procedures for situations where no RAR is received may be implemented. If no RAR is received, retransmission may be considered. If the WTRU does not receive RAR within the configured RAR time window, the WTRU may perform RACH retransmissions based on configured TA adjustment values (e.g., hysteresis values, or ±TA step values) (e.g., configured via second set of configurations) in addition to configured power ramping values.

[0277] In case no RAR is received, the WTRU may perform a retransmission in the first resources (e.g., indicated by the first configuration information). For example, if the WTRU does not receive RAR within the configured RAR time window (e.g., despite retransmissions based on power ramping and TA adjustments), the WTRU may determine to transmit Msgl / MsgA using resources configured in the first RA configurations, using the predicted TA (TA > 0).

[0278] The WTRU may monitor to receive RAR, where RAR may include TA command based on one or more configurations. In some examples (e.g., for 2-step RACH), since the WTRU reports the predicted TA in the transmitted MsgA PUSCH, the RAR may include an indication that WTRU can use the predicted TA in addition to TA adjustment command included in RAR to determine a second TA applicable for a subsequent transmission.

[0279] In some examples, the WTRU may add the received absolute TA command value to the predicted TA to determine the second UL TA. For example, if 4-step RACH and / or if the TA is not reported in the MsgA, and since the RACH was transmitted in first resources, the gNB may have no idea that predicted TA is used at the WTRU for RACH transmission. So, RAR may include absolute TA command. The WTRU may report the determined second TA in Msg3, or as part of next PUCCH and / or PUSCH transmission to gNB.

[0280] In case no RAR is received, the WTRU may check for an updated SIB. The WTRLI may monitor and receive SIB1 again for the determined SSB, within a configured time window (e.g., configured based on the TA-P-RACH set of configurations).

[0281] In some examples, the WTRU may receive a new second set of resources and determine if the new second set of resources is different from the old received second set. For instance, the WTRU may determine if any updates to the second set of resources or configurations have been indicated via gNB. The second set of configurations may include, for example, a set of RACH time and freq, resources, RACH configs with shorted gaps and guard time, preamble formats, and / or MsgA configs, etc.

[0282] If the WTRU determines that the second set of resources is updated, the WTRU may use the new second set of resources for RACH transmission based on the predicted TA.

[0283] In case no RAR is received, the WTRU may fall back. For example, if the WTRU does not receive RAR, the WTRU may fall back to send RACH with TA=0 using the first set of resources. The WTRU may send an indication that RACH based on predicted TA was not successful (e.g., No RAR received). The WTRU may report the predicted TA.

[0284] In some examples, if WTRU does not receive RAR within the configured time limit and / or time window, the WTRU may determine one or more procedures to be supported by the WTRU. The WTRU may determine the procedures based on one or more conditions that are satisfied. For example, one or more of the following example conditions may apply.

[0285] For example, if the WTRU does not receive random access response (RAR) within an associated and / or configured RAR time window (e.g., configured and / or indicated based on milliseconds (ms), microseconds, nanoseconds (ns), number of symbols, slots, subframes, etc., and / or expiration of a counter) after a first type of transmission (e.g., initial RACH transmission without UL time adjustment), the WTRU may determine one or more procedures to be supported by the WTRU.

[0286] For example, if the WTRU does not receive RAR within an associated and / or configured RAR time window (and / or expiration of a counter) after a second type of transmission (e.g., retransmission with determined, predicted, and / or configured TA adjustment values), the WTRU may determine one or more procedures to be supported by the WTRU.

[0287] For example, if the WTRU does not receive RAR within an associated and / or configured RAR time window (and / or expiration of a counter) after a third type of transmission (e.g., retransmission with determined, predicted, and / or configured TA adjustment values and power ramping), the WTRU may determine one or more procedures to be supported by the WTRU.

[0288] For example, if the WTRU does not receive RAR within an associated and / or configured RAR time window (and / or expiration of a counter) after a fourth type of transmission (e.g., transmission based on new configurations by receiving updated SIB (e.g., SIB1), the WTRU may determine one or more procedures to be supported by the WTRU.

[0289] The WTRU may determine one or more of the following procedures. In some examples, the WTRU may perform RACH retransmissions based on determined, predicted, and / or configured TA adjustment values. For example, the WTRU may determine the adjustment values based on configured and / or determined values. In an example, the WTRU may determine or be configured with hysteresis values to be used for adjusting the TA. In another example, the WTRU may determine or be configured with one or more step values for adjusting the predicted, determined, and / or configured TA values. For example, the WTRU may receive one or more configuration information on the adjustment values as part of a second set of configurations that is used for RACH transmission, for example based on WTRU-sided determined and / or predicted TA. In an example, the WTRU may apply the TA adjustments in addition to one or more determined and / or configured power ramping values. The WTRU may perform RACH retransmissions based on determined, predicted, and / or configured TA adjustment values, if the WTRU does not receive random access response (RAR) within an associated and / or configured RAR time window (e.g., configured and / or indicated based on ms, microseconds, ns, number of symbols, slots, subframes, etc.) (and / or expiration of a counter) after a first type of transmission (e.g., initial RACH transmission without UL time adjustment).

[0290] In some examples, the WTRU may perform retransmission in one or more first resources. For example, the WTRU may transmit Msg1 or MsgA in a first set of time and frequency resources based on the predicted TA (e.g., for TA > 0). Based on the transmission, the WTRU may monitor to receive a RAR, where the RAR may include TA command based on one or more of the following. For instance, the WTRU may report the predicted TA in the transmitted MsgA PUSCH and / or the RAR may include an indication that the WTRU may use the predicted TA (e.g., in addition to TA adjustment command included in RAR). For instance, the RAR may include an absolute TA command. In this case, the WTRU may use a different method for determining a new TA. For example, the WTRU may add the received absolute TA command to the predicted TA to determine the new TA. The WTRU may report the newly determined TA in one or more of Msg3, PUCCH, and / or PUSCH (e.g., as part of next PUCCH and / or PUSCH transmission to gNB). The WTRU may perform retransmission in one or more first resources, for example, if the WTRU does not receive RAR within an associated and / or configured RAR time window (and / or expiration of a counter) aftera second type of transmission (e.g., retransmission with determined, predicted, and / or configured TA adjustment values). Further, the WTRU may perform retransmission in one or more first resources, for example, if the WTRU does not receive RAR within an associated and / or configured RAR time window (and / or expiration of a counter) after a third type of transmission (e.g., retransmission with determined, predicted, and / or configured TA adjustment values and power ramping).

[0291] In some examples, the WTRU may perform a RACH transmission based on new indication, for example via SIB. The WTRU may receive a new second set of resources. Based on the reception, the WTRU may determine if the new second set of resources is different from the old received second set. For instance, the WTRU may determine if any updates to the second set of resources or configurations have been indicated (e.g., from gNB). The second set of configurations may include one or more of set of RACH time and frequency resources, RACH configs with shorted gaps and guard time, preamble formats, MsgA configs, etc. If the WTRU determines that the second set of resources is updated, the WTRU may use the new second set of resources for RACH transmission based on the predicted TA. The WTRU may perform a RACH transmission based on new indication (e.g., via SIB), for example, if the WTRU does not receive RAR within an associated and / or configured RAR time window (and / or expiration of a counter) after a second type of transmission (e.g., retransmission with determined, predicted, and / or configured TA adjustment values). Further, The WTRU may perform a RACH transmission based on new indication (e.g., via SIB), for example, if the WTRU does not receive RAR within an associated and / or configured RAR time window (and / or expiration of a counter) after a third type of transmission (e.g., retransmission with determined, predicted, and / or configured TA adjustment values and power ramping).

[0292] In some examples, the WTRU may fall back for RACH configuration. For example, the WTRU may transmit RACH with TA=0 in the first set of configured time and frequency resources. For instance, the WTRU may send an indication reflecting the situation. For example, the WTRU may indicate that RACH based on predicted TA was not successful (e.g., due to no RAR reception at the WTRU). In another example, the WTRU may indicate the predicted TA (e.g., to the gNB). The WTRU may fall back for RACH configuration, for example, if the WTRU does not receive RAR within an associated and / or configured RAR time window (and / or expiration of a counter) after a fourth type of transmission (e.g., transmission based on new configurations by receiving updated SIB (e.g., SIB1).

Claims

CLAIMS:1 . A wireless transmit / receive unit (WTRU) comprising: a processor configured to: receive configuration information that indicates that WTRU-sided timing advance (TA) prediction is enabled; receive a first set of configurations for a random access channel (RACH) transmission and a second set of configurations for a RACH transmission; determine an accuracy of a predicted TA; determine whether to use the first set of configurations or the second set of configurations for a RACH transmission, wherein the first set of configurations is used for the RACH transmission when the accuracy of the predicted TA is below a threshold value, and wherein the second set of configurations is used for the RACH transmission when the accuracy of the predicted TA is above the threshold value; and send the RACH transmission using the first set of configurations or the second set of configurations.

2. The WTRU of claim 1 , wherein the second set of configurations has shortened guard bands and guard times as compared to the first set of configurations.

3. The WTRU of claim 1 or 2, wherein the processor is configured to receive a random access response (RAR) message that indicates whether the WTRU should continue to use the predicted TA or use a network provided TA.

4. The WTRU of claim 3, wherein the RAR message comprises the network provided TA.

5. The WTRU of any of claims 1 to 4, wherein the processor is configured to determine the accuracy of the predicted TA based on any combination of time stamps of one or more reference signals (RSs), medium access control-control elements (MAC-CEs), system information blocks (SIBs), a location or position of the WTRU within a cell, a mobility state of the WTRU, a predictive model, or a channel impulse response (CIR) based on one or more downlink (DL) RSs.

6. The WTRU of any of claims 1 to 5, wherein the processor is configured to:receive configuration information that indicates the location of the WTRLI; determine the distance of the WTRU from a gNB based on the WTRU’s indicated location; and determine that the accuracy of the TA prediction is valid if the distance between the WTRU and the gNB is lower than a preconfigured threshold.

7. The WTRU of any of claims 1 to 6, wherein the processor is configured to: use a two-step RACH procedure with the second set of configurations for a RACH transmission if the accuracy of the predicted TA is above the threshold value and a measured reference signal received power (RSRP) is above an RSRP threshold for 2-step RACH; and use a four-step RACH procedure with the second set of configurations for a RACH transmission if the accuracy of the predicted TA is above the threshold value and the measured RSRP is below the RSRP threshold for 2-step RACH.

8. The WTRU of any of claims 1 to 7, wherein each of the first and second set of configurations comprises a set of RACH time and frequency resources, a set of preambles, a RACH configuration, a preamble format, a time alignment timer (TAT) value, or an RSRP threshold for 2-step RACH.

9. The WTRU of any of claims 1 to 8, wherein the configuration information comprises a flag indication that enables TA prediction for capable WTRUs, and wherein the flag indication is via one or more of SIB, radio resource control (RRC), MAC-CE, or downlink control information (DCI).

10. The WTRU of any of claims 1 to 9, wherein the processor is configured to: use the second set of configurations for the RACH transmission if the accuracy of the predicted TA is higher than the threshold or determined to be valid; and send a preamble message in a message one (MSG1) using the predicted TA.11 . The WTRU of any of claims 1 to 9, wherein the processor is configured to: use the second set of configurations for the RACH transmission if the accuracy of the predicted TA is higher than the threshold or determined to be valid; and send a preamble message and physical uplink shared channel (PUSCH) transmission in a message A (MSGA) using the predicted TA.

12. The WTRU of any of claims 1 to 11 , wherein the processor is configured to start or restart a TAT based on a configured second TAT.

13. The WTRU of any of claims 1 to 12, wherein the processor is configured to monitor to receive a RAR message within a configured RAR window.

14. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving configuration information that indicates that WTRU-sided timing advance (TA) prediction is enabled; receiving a first set of configurations for a random access channel (RACH) transmission and a second set of configurations for a RACH transmission; determining an accuracy of a predicted TA; determining whether to use the first set of configurations or the second set of configurations for a RACH transmission, wherein the first set of configurations is used for the RACH transmission when the accuracy of the predicted TA is below a threshold value, and wherein the second set of configurations is used for the RACH transmission when the accuracy of the predicted TA is above the threshold value; and sending the RACH transmission using the first set of configurations or the second set of configurations.

15. The method of claim 14, wherein the second set of configurations has shortened guard bands and guard times as compared to the first set of configurations.

16. The method of claim 14 or 15, wherein the method further comprises receiving a random access response (RAR) message that indicates whether the WTRU should continue to use the predicted TA or use a network provided TA.

17. The method of claim 16, wherein the RAR message comprises the network provided TA.

18. The method of any of claims 14 to 17, wherein the method further comprises determining the accuracy of the predicted TA based on any combination of time stamps of one or more reference signals(RSs), medium access control-control elements (MAC-CEs), system information blocks (SIBs), a location or position of the WTRU within a cell, a mobility state of the WTRU, a predictive model, or a channel impulse response (CIR) based on one or more downlink (DL) RSs.

19. The method of any of claims 14 to 18, wherein the method further comprises: receiving configuration information that indicates the location of the WTRU; determining the distance of the WTRU from a gNB based on the WTRU’s indicated location; and determining that the accuracy of the TA prediction is valid if the distance between the WTRU and the gNB is lower than a preconfigured threshold.

20. The method of any of claims 14 to 19, wherein the method further comprises: using a two-step RACH procedure with the second set of configurations for a RACH transmission if the accuracy of the predicted TA is above the threshold value and a measured reference signal received power (RSRP) is above an RSRP threshold for 2-step RACH; and using a four-step RACH procedure with the second set of configurations for a RACH transmission if the accuracy of the predicted TA is above the threshold value and the measured RSRP is below the RSRP threshold for 2-step RACH.

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