Methods, apparatuses and systems directed to network access for non-terrestrial networks

Abstract

To provide methods, apparatuses, systems, etc. for, and / or for use in connection with, performing network access and / or other procedures in a non-terrestrial network (NTN) of a communication system.SOLUTION: Among methods, there are methods that may be implemented in a wireless transmit / receive unit (WTRU) and may include any of receiving, from the NTN, differential delay information and physical random access channel (PRACH) configuration information indicating a set of preambles and a PRACH occasion configuration; determining a set of candidate PRACH occasions, from among a plurality of PRACH occasions of the PRACH occasion configuration, on the basis of the differential delay information; selecting a preamble from a group of the preambles allocated to one candidate PRACH occasion of the set of candidate PRACH occasions; and transmitting the selected preamble using a PRACH resource corresponding to the one candidate PRACH occasion.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a method, apparatus, and system directed to network access to non-terrestrial networks. [Background technology]

[0002] TECHNICAL FIELD This disclosure relates to network communications, including, but not limited to, methods, apparatus, systems, etc., directed to network access to non-terrestrial networks. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS38.811, “Study on New Radio (NR) to support non-terrestrial networks”, V15.0.0 Summary of the Invention [Problem to be solved by the invention]

[0004] A method, apparatus, and system for network access to non-terrestrial networks are provided. [Means for solving the problem]

[0005] A method, apparatus, system, etc. for performing and / or use in connection with a non-terrestrial network (NTN) of a communication system, the method may include receiving, from a wireless transmit / receive unit (WTRU), differential delay information and physical random access channel (PRACH) configuration information indicating a set of preambles and a PRACH occasion configuration from the NTN, determining a set of candidate PRACH opportunities from among a plurality of PRACH opportunities of the PRACH occasion configuration based on the differential delay information, selecting a preamble from a group of preambles assigned to a candidate PRACH opportunity of the set of candidate PRACH opportunities, and transmitting the selected preamble using a PRACH resource corresponding to the one candidate PRACH opportunity.

[0006] A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawings, in which: Figures in such drawings, such as the detailed description, are examples; thus, the figures and detailed description should not be considered as limiting, and other equally valid examples are possible and may be appropriate. Moreover, like reference numerals in the figures indicate like elements. Effect of the Invention

[0007] A method, apparatus, and system for network access to non-terrestrial networks are provided. [Brief description of the drawings]

[0008] [Figure 1A] FIG. 1 illustrates an exemplary communication system in which one or more embodiments may be implemented. [Figure 1B] FIG. 1B illustrates an example wireless transmit / receive unit (WTRU) that may be used in the communications system of FIG. 1A in accordance with an embodiment. [Figure 1C]FIG. 1B illustrates an exemplary radio access network (RAN) and core network (CN) for use in the communication system of FIG. 1A in accordance with an embodiment. [Figure 1D] FIG. 1B illustrates a further exemplary RAN and CN for use in the communication system of FIG. 1A according to an embodiment. [Diagram 2] FIG. 1 illustrates an example of a four-step initial access procedure. [Diagram 3] FIG. 1 is a system resource diagram illustrating an example preamble group allocation for synchronization signal blocks (SSBs). [Figure 4] A system resource diagram showing an example preamble group allocation to an SSB set. [Diagram 5] FIG. 1 is a system resource diagram illustrating an example of preamble group allocation. [Figure 6] A system resource diagram showing an example preamble group allocation to an SSB set. [Figure 7] FIG. 1 is a system resource diagram illustrating an example preamble group allocation. [Figure 8] FIG. 11 is a flow diagram illustrating an example preamble group allocation procedure. [Figure 9] FIG. 11 is a flow diagram illustrating an example preamble group allocation procedure. [Figure 10] FIG. 13 is a system resource diagram of an example of time indexing of PRACH opportunities. [Figure 11] FIG. 1 is a system resource diagram illustrating an example of multiple Msg1 transmissions before a random access response (RAR). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Although various embodiments are described and / or claimed herein in which apparatus, systems, devices, etc., and / or any elements thereof perform operations, processes, algorithms, functions, etc., and / or any portions thereof, it is to be understood that any embodiment described and / or claimed herein may be construed as any apparatus, system, device, etc., and / or any elements thereof being configured to perform any operation, process, algorithm, function, etc., and / or any portion thereof.

[0010] Exemplary Communication Network FIG. 1A is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communication system 100 may utilize 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-tailed Unique Word DFT Spread OFDM (ZT UW DTS-s OFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, and Filter Bank Multi-Carrier (FBMC).

[0011] 1A, 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, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and / or “STA,” may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearables, head mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain situations), consumer electronics devices, and devices operating on commercial and / or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, 102d may be referred to interchangeably as UEs.

[0012] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B (eNB), a Home Node B (HNB), a Home eNode B (HeNB), a gNB, a NR Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0013] 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 a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for wireless services in a particular geographic area, which may be relatively constant or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, e.g., one for each sector of the cell. In an embodiment, the base station 114a may utilize multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell, e.g., beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0014] 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).

[0015] More specifically, as mentioned above, the communication system 100 may be a multiple access system and may utilize one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA. 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 116 using Wideband CDMA (WCDMA). WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0016] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE), and / or LTE Advanced (LTE-A), and / or LTE Advanced Pro (LTE-A Pro).

[0017] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as New Radio (NR) radio access, which may establish the air interface 116 using NR.

[0018] 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, e.g., using a dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0019] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (e.g., Wireless Fidelity (WiFi)), IEEE 802.16 (e.g., Global 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), and GSM EDGE (GERAN).

[0020] 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a localized area, such as an office, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., used by drones), and a roadway. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a wireless 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 wireless 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 establish a picocell or a femtocell using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). 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 need to access the Internet 110 via the CN 106 / 115.

[0021] The RAN 104 / 113 may communicate with the CN 106 / 115, which may be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various Quality of Service (QoS) requirements, such as different throughput requirements, delay requirements, error resilience requirements, reliability requirements, data throughput requirements, and mobility requirements. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, 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 communicate directly or indirectly with other RANs that utilize 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 utilize NR radio technology, the CN 106 / 115 may also communicate with another RAN (not shown) that utilizes GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0022] 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 other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communications protocols, such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) in the TCP / IP Internet protocol suite. The network 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs that may utilize the same RAT as the RAN 104 / 113 or a different RAT.

[0023] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may utilize a cellular-based wireless technology and with a base station 114b that may utilize an IEEE 802 wireless technology.

[0024] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a Global Positioning System (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any subcombination of the above elements while remaining consistent with an embodiment.

[0025] The processor 118 can be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors in conjunction with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 can 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 can be coupled to the transceiver 120, which can be coupled to the transmit / receive element 122. Although FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0026] The transmit / receive element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0027] 1B, the transmit / receive element 122 is depicted as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may utilize 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.

[0028] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0029] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may obtain information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a 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 located on a server or home computer (not shown).

[0030] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components within the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0031] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or may determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information using any suitable location determination method while remaining consistent with an embodiment.

[0032] 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 photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, 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.

[0033] The WTRU 102 may include a full-duplex radio where the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and the downlink (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit to reduce and / or substantially eliminate self-interference via hardware (e.g., a choke) or via signal processing via a processor (e.g., a separate processor (not shown) or the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or the downlink (e.g., for reception).

[0034] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to an embodiment. As mentioned above, the RAN 104 can communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using E-UTRA radio technology. The RAN 104 can also communicate with the CN 106.

[0035] The RAN 104 may include eNodeBs 160a, 160b, 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, 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 eNodeBs 160a, 160b, 160c may implement MIMO technology. Thus, the eNodeB 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0036] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG 1C, the eNodeBs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0037] 1C may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (or PGW) 166. Although each of the above elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity different from the CN operator.

[0038] The MME 162 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0039] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-eNodeB handover, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, as well as managing and storing the context of the WTRUs 102a, 102b, 102c.

[0040] The SGW 164 may be connected to a PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0041] 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 landline communications devices. For example, the CN 106 may include or 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 other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0042] Although in Figures 1A-1D the WTRU is described as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may use a wired communications interface (e.g., temporarily or permanently) with the communications network.

[0043] In an exemplary embodiment, the other network 112 may be a WLAN.

[0044] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic within and / or outside the BSS. Traffic to a STA originating from outside the BSS may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP for delivery to the respective destination. Traffic between STAs in the BSS may be sent through the AP, e.g., a source STA may send traffic to the AP, which may deliver the traffic to the destination STA. Traffic between STAs in the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent (e.g., directly) between a source STA and a destination STA using a direct link setup (DLS). In one representative embodiment, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs (e.g., all of the STAs) in or using an IBSS may communicate directly with each other. IBSS mode communication is sometimes referred to herein as an "ad-hoc" mode of communication.

[0045] When using 802.11ac infrastructure mode of operation or a similar mode of operation, the AP may transmit beacons 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 width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by STAs to establish a connection with the AP. In one representative embodiment, for example, in an 802.11 system, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented. With CSMA / CA, STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected by a particular STA and / or determined to be busy, the particular STA may back off. Within a given BSS, one STA (e.g., only one station) may transmit at any given time.

[0046] High-throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0047] A Very High Throughput (VHT) STA can support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz and / or 80 MHz channels can be formed by combining contiguous 20 MHz channels. The 160 MHz channel can be formed by combining eight 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, can pass through a segment parser that can split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time domain processing can be performed separately for each stream. The streams can be mapped onto two 80 MHz channels and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration can be reversed and the combined data can be transmitted to the Medium Access Control (MAC).

[0048] Sub-1 GHz mode operation is supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. In accordance with a representative embodiment, 802.11ah can support meter-type control / machine-type communication, such as MTC devices in macro coverage areas. MTC devices can have limited functionality, including, for example, support of (e.g., only) a certain bandwidth and / or limited bandwidth. MTC devices can include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0049] A WLAN system, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, that may support multiple channels and channel bandwidths, includes a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA that supports a minimum bandwidth operating mode among all STAs operating in the BSS. In an 802.11ah example, for a STA (e.g., an MTC type device) that supports (e.g., only supports) the 1 MHz mode, the primary channel may be 1 MHz wide, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) setting may depend on the status of the primary channel. For example, if the primary channel is busy because a STA (that only supports a 1 MHz mode of operation) is transmitting to the AP, the entire available frequency band may be considered busy, even though most of the available frequency band may remain idle and available.

[0050] In the United States, the available frequency bands that can be used by 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total available bandwidth for 802.11ah is 6MHz to 26MHz, depending on country regulations.

[0051] 1D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As mentioned above, the RAN 113 may communicate with the WTRUs 102a, 102b, 102c over the air interface 116 utilizing NR radio technology. The RAN 113 may also communicate with the CN 115.

[0052] The RAN 113 may include gNBs 180a, 180b, 180c, although it will be understood 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, the gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may transmit wireless signals to and / or receive wireless signals from the WTRU 102a using multiple antennas, for example. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multipoint (CoMP) techniques. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or gNB 180c).

[0053] The WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing can be varied for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., including different numbers of OFDM symbols and / or lasting for different lengths of absolute time).

[0054] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing other RANs (e.g., eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect to a gNB 180a, 180b, 180c while also communicating / connecting to another RAN, such as the eNodeBs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeBs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0055] Each of the gNBs 180a, 180b, 180c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, and routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, the gNBs 180a, 180b, 180c can communicate with each other over the Xn interface.

[0056] The CN 115 shown in Figure 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although each of the above elements is depicted as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity different from the CN operator.

[0057] 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 act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating non-access stratum (NAS) signaling, and mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service utilized by the WTRUs 102a, 102b, 102c. Different network slices may be established for different use cases, such as, for example, services relying on ultra-reliable low latency communications (URLLC) access, services relying on high speed mobile (e.g., large capacity mobile) broadband (eMBB) access, and / or services for machine type communications (MTC) access, etc. 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.

[0058] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also be connected to the UPFs 184a, 184b in the CN 115 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as managing and assigning WTRU / UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notification. The PDU session types may be IP-based, non-IP-based, Ethernet-based, etc.

[0059] The UPFs 184a, 184b may connect 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 UPFs 184a, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homing PDU sessions, handling user plane QoS, buffering downlink packets, as well as providing mobility anchoring.

[0060] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or 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 other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may connect to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0061] In view of Figures 1A-1D and the corresponding description thereof, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNodeBs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices 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.

[0062] The emulation device may be designed to perform one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, the one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. The one or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for testing purposes and / or may perform the tests using over-the-air wireless communication.

[0063] The one or more emulation devices can perform one or more functions, including all functions, without being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices can be utilized in a test lab and / or in a test scenario in a non-deployed (e.g., test) wired and / or wireless communication network to perform testing of one or more components. The one or more emulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, for example, one or more antennas) can be used by the emulation devices to transmit and / or receive data.

[0064] Next-generation air interfaces include further evolution of Long Term Evolution (LTE) Advanced Pro, and New Radio (NR). They support a wide range of use cases including various service requirements (e.g., low overhead low data rate power efficient services, (High Capacity Machine Type Communications (mMTC)), Ultra Reliable Low Latency Communications (URLLC) services, and high data rate mobile broadband services (Enhanced Mobile Broadband (eMBB))) for various radio transmit / receive unit (WTRU) capabilities (low power low bandwidth WTRU, WTRU capable of very wide bandwidth, e.g., 80 MHz, WTRU support for high frequencies, e.g., above 6 GHz) under various mobility scenarios (e.g., stationary / fixed, high speed train, etc.). They use architectures flexible enough to fit various deployment scenarios (e.g., standalone, non-standalone with assistance from different air interfaces, centralized, virtualized, distributed over ideal / non-ideal backhaul, etc.).

[0065] Beamforming may be used to compensate for increased path loss at higher frequencies (e.g., above 6 GHz). Multiple antenna elements may be used to achieve high beamforming gain. Analog and / or hybrid beamforming may be used to lower implementation costs (e.g., reduce the number of radio front-end (RF) chains, etc.). In NR, analog / hybrid beams are multiplexed in time and may also use beam sweeping (e.g., to cover a wide area). During the initial access procedure, the WTRU may (and may need to) monitor multiple downlink reference signals to identify an appropriate beam to access the network.

[0066] Non-terrestrial networks (NTNs) are discussed in Non-Patent Document 1. They can facilitate the deployment of 5G services in unserved areas (e.g., isolated remote areas, rural areas, ships at sea, etc.). NTNs can be used to improve the performance of terrestrial networks in unserved areas in a cost-effective manner. NTNs can be used to enhance the reliability of 5G services, ensure service availability, and provide scalability for 5G deployment.

[0067] Disclosed herein are methods, apparatus, systems, etc. directed to either initial and other network access in a combined terrestrial and non-terrestrial network (NTN) (collectively, "network").

[0068] Among such methods are methods directed to disambiguation of PRACH occasions / resources during network access procedures, including disambiguation between PRACH occasions / resources used by a wireless transmit / receive unit (WTRU) and network determination of such PRACH occasions / resources. For example, such methods may handle (or address) uncertainties that may otherwise arise during network access.

[0069] In various embodiments, methods for performing initial or other network access to an NTN and / or methods used in connection therewith may be implemented in a WTRU and may include any of the following:

[0070] In various embodiments, a method for performing initial or other network access to an NTN and / or methods used in connection therewith may be performed in a WTRU and may include any of generating a preamble message ("Msg1"), sending Msg1 to the NTN, receiving a response message ("Msg2") from the NTN, generating a connection request message ("Msg3"), sending Msg3 to the NTN, and receiving a contention resolution message ("Msg4") from the NTN. In various embodiments, Msg1 and Msg3 may be sent together (e.g., sent in combination) in a message (MsgA). In various embodiments, Msg2 and Msg4 (e.g., a combination thereof) may be received together in a message ("MsgB").

[0071] In various embodiments, the method can include receiving a timing offset of the NTN. In various embodiments, the method can include determining a downlink (DL) transmission timing of the network based on the timing offset. In various embodiments, the method can include sending Time Advance (TA) information in Msg1.

[0072] In various embodiments, the method may include selecting a physical random access channel (PRACH) configuration for transmitting Msg1. In various embodiments, the method may include selecting a PRACH preamble group from a set of PRACH preamble groups corresponding to different ranges of TAs between the WTRU and the network. In various embodiments, the method may include determining a number of preamble groups based on a number of PRACH resources included in a delay difference period. In various embodiments, the method may include selecting a PRACH preamble group based on a delay difference period and an SSB. In various embodiments, the method may include selecting at least one frequency resource for transmitting Msg1 based on a PRACH transmission time included in the delay difference period. In various embodiments, the method may include determining a delay difference period. In various embodiments, the method may include selecting a PRACH preamble group based on a position of the PRACH resource and an associated synchronization signal block (SSB). In various embodiments, the method may include performing Doppler compensation. In various embodiments, the method may include performing Doppler compensation based on a velocity vector. In various embodiments, the method may include determining a Random Access-Radio Network Temporary Identifier (RA-RNTI) based on the (e.g., selected) PRACH configuration.

[0073] In various embodiments, the method may include determining an initial frame for time indexing and / or for determining the RA-RNTI. In various embodiments, the method may include determining a time index for a PRACH time instance. In various embodiments, the method may include adjusting a transmit power of Msg1. In various embodiments, the method may include decoding Msg2 by using one or more RA-RNTIs determined within a delay difference period.

[0074] In various embodiments, the method may include any of determining a RACH configuration for transmitting any of Msg1, Msg3, and MsgA. In various embodiments, the method may include determining a RACH configuration for transmitting any of Msg1, Msg3, and MsgA based on one or more factors. In various embodiments, the one or more factors may include any of (i) a type of WTRU, (ii) a class of WTRU, (iii) whether the WTRU is GNSS capable, (iv) a capability to estimate timing advance (TA), (v) a capability to estimate position, (vi) a Doppler compensation capability, (vii) a size of Msg1, Msg2, and / or MsgA, (viii) an estimated TA, and (ix) a predicted TA.

[0075] In various embodiments, the method may include selecting one or more parameters for the RACH configuration. In various embodiments, the one or more parameters may include any of: (i) a preamble index, (ii) a resource for the preamble transmission, (iii) a number of preamble transmissions, (iv) a resource for the PUSCH, (v) a number of PUSCH transmissions, (vi) a redundancy version (RV) sequence, (vii) an association between the preamble and the PUSCH, (viii) a transmit power for the PUSCH, and (ix) a modulation and coding scheme (MCS) for the PUSCH. In various embodiments, the method may include configuring the WTRU with the one or more parameters. In various embodiments, the method may include receiving the one or more parameters from the NTN.

[0076] In various embodiments, determining a RACH configuration for transmitting any of Msg1, Msg3, and MsgA may include determining the number of PUSCH and / or preamble transmissions based on the estimated TA. In various embodiments, determining a RACH configuration for transmitting any of Msg1, Msg3, and MsgA may include determining to use one preamble and one or more PUSCH transmissions based on the ability to accurately estimate TA. In various embodiments, determining a RACH configuration for transmitting any of Msg1, Msg3, and MsgA may include determining to use one preamble with multiple PUSCH transmissions based on not having the ability to accurately estimate TA. In various embodiments, the method may include determining a RACH configuration for transmitting any of Msg1, Msg3, and MsgA may include determining to use multiple transmissions of both preambles and PUSCH based on not having the ability to accurately estimate TA.

[0077] In various embodiments, the method can include informing the NTN (e.g., a network entity) of the estimated TA. In various embodiments, informing the NTN of the estimated TA can include informing the NTN of the estimated TA with MsgA. In various embodiments, informing the NTN of the estimated TA can include sending the estimated TA and / or an index corresponding to a table of estimated TAs with MsgA. In various embodiments, informing the NTN of the estimated TA can include implicitly informing the NTN of the estimated TA by using a particular parameter or combination of parameters for MsgA.

[0078] In various embodiments, the method may include determining one or a combination of various transmission characteristics to use for transmission and / or retransmission of MsgA. In various embodiments, the method may include determining one or a combination of various transmission characteristics to use for transmission and / or retransmission of MsgA based on a reception status of MsgB. In various embodiments, the reception status of MsgB may include any of the following: no MsgB, MsgB decoding failure, MsgB indicates ACK for preamble and NACK for PUSCH, MsgB indicates NACK for preamble and ACK for PUSCH, and MsgB indicates ACK for both preamble and PUSCH.

[0079] In various embodiments, the various transmission characteristics may include (i) performing a power boost for the preamble, (ii) adjusting the transmit power, (iii) adjusting the modulation and coding scheme (MCS) for the PUSCH, (iv) switching from a 2-step RACH to a 4-step RACH, (v) adjusting the number of PUSCH transmissions, (vi) adjusting the number of preamble transmissions, (vii) adjusting the estimated TA value, (viii) using a different resource configuration for MsgA, (ix) selecting a particular preamble format, and (x) using or switching to a different (e.g., different) preamble format.

[0080] In various embodiments, the method may include determining a transmit power, TxP, for Msg1 based at least in part on various satellite information received from the network, for example. In various embodiments, the satellite information may include any of the following: a target power at which the preamble is received, a power increase step, a satellite transmit power, a satellite type, an altitude, a speed, and ephemeris data. In various embodiments, the method may include receiving the satellite information in any of the L1, L2, and / or L3 signaling.

[0081] In various embodiments, the method may include determining a received power based on a reference signal. In various embodiments, the determined received power may include a reference signal received power (RSRP).

[0082] In various embodiments, the method may include estimating a path loss (PL) at time t1 based on a satellite transmit power and a receive power based on a reference signal. In various embodiments, the method may include predicting a PL at time t2 based on any of a calculated distance to an associated satellite at time t1, an estimated PL at time t1, and a predicted distance to the satellite at time t2. In various embodiments, the method may include calculating a distance from the satellite at time t1 based on satellite information. In various embodiments, the satellite information may include satellite altitude and ephemeris data. In various embodiments, the method may include predicting a distance from the satellite at time t2 based on information including any of the WTRU, satellite altitude, velocity, and ephemeris data.

[0083] In various embodiments, the method may include calculating two transmit powers, TxP1, TxP2. In various embodiments, the first and second transmit powers TxP1, TxP2 may be based on an estimated PL and a predicted PL, respectively. In various embodiments, the first transmit power TxP1 may be calculated as a combination of a target power at which the preamble is received and the estimated PL, and the second transmit power TxP2 may be calculated as a combination of a target power at which the preamble is received and the predicted PL. In various embodiments, the target power at which the preamble is received may be obtained from satellite information.

[0084] In various embodiments, the method may include determining a transmit power TxP for Msg1 based on the first and second transmit powers TxP1, TxP2. In various embodiments, determining the transmit power TxP for Msg1 may include determining the transmit power TxP for Msg1 as a maximum, average, or other function of the first and second transmit powers TxP1, TxP2.

[0085] In various embodiments, the method may include setting and / or applying a transmit power TxP for Msg1 according to TxP=min(max power, f(TxP1, TxP2)), where max power may be a maximum transmit power and f(TxP1, TxP2) is a function applied to either the first and second transmit powers TxP1, TxP2.

[0086] In various embodiments, the method can include adjusting a first transmit power TxP1 according to a power increase step for the retransmission of Msg1. In various embodiments, the method can include determining a transmit power TxP for the retransmission of Msg1 based at least in part on various satellite information received from the network, for example.

[0087] In various embodiments, the method may include determining a third transmit power, TxP3, for retransmitting Msg1 based on a second predicted PL between the WTRU and the satellite at time t3 when Msg1 is intended and / or predicted to reach the satellite after retransmission. In various embodiments, the method may include predicting the second predicted PL at time t3 based on (e.g., using) any of a calculated distance to the associated satellite at time t1, an estimated PL at time t1, and a predicted distance to the satellite at time t3. In various embodiments, the method may include setting and / or applying a transmit power TxP to retransmit Msg1 according to TxP=min(max power, f(TxP1+power increase step, TxP3)), where max power may be the maximum transmit power and f(TxP1(t1)+power increase step, TxP2(t2)) is a function applied to TxP1(t1)+power increase step and / or TxP2(t2).

[0088] In various embodiments, a method for and / or used in connection with performing network access to an NTN and / or performing other procedures in the NTN may be performed in a WTRU and may include either receiving Doppler shift compensation information from a network entity or performing Doppler pre-compensation after receiving the Doppler shift compensation. In various embodiments, the Doppler shift compensation information may be a Doppler shift compensation command.

[0089] In various embodiments, the network entity may be a base station. In various embodiments, the Doppler shift compensation information may be received in any of Layer 1 (L1), Layer 2 (L2), and Layer 3 (L3) signaling. In various embodiments, the method may include the Doppler shift compensation information may be received in (or by) any of a Media Access Control (MAC) Control Element (CE) and a Radio Resource Control (RRC) message.

[0090] In various embodiments, performing Doppler pre-compensation can include adjusting the Doppler shift pre-compensation with a previously pre-compensated Doppler shift. In various embodiments, the method can include the previously pre-compensated Doppler shift being based on (e.g., by) information received from a network (e.g., a base station). In various embodiments, the previously pre-compensated Doppler shift can be based on (e.g., by) a last UL transmission.

[0091] In various embodiments, a method for and / or used in connection with performing network access to an NTN and / or performing other procedures in an NTN may be performed in a WTRU and may include determining which of one or more synchronization rasters to use based on a type of satellite ("satellite type"). In various embodiments, each (or any) of the synchronization rasters may be associated with one or more satellite types. In various embodiments, the method may include that determining which of the synchronization rasters to use may include determining which synchronization raster to use based on the satellite type being targeted and / or accessed. In various embodiments, a large synchronization raster is used for LEO satellites. In various embodiments, a small synchronization raster is used for GEO satellites.

[0092] In various embodiments, a method for and / or used in connection with performing network access to an NTN and / or performing other procedures in an NTN may be performed in a WTRU and may include determining SSB timing of multiple beams transmitted by a satellite based on the timing of one SSB and a timing pattern between the beams. In various embodiments, the timing pattern may be a (pre-)defined timing pattern. In various embodiments, determining the SSB timing may include determining times to monitor different frequencies to detect SSBs from beams transmitted by the satellite based on the SSB timing of the different beams.

[0093] In various embodiments, a method for and / or used in connection with performing network access to an NTN and / or performing other procedures in the NTN may be performed in a WTRU and may include either monitoring a group-common PDCCH (GC-PDCCH) and receiving an indication of a TA command (TAC) for one or more WTRUs. In various embodiments, the method may include adjusting the TA to that of the group of WTRUs indicated in / by the TAC. In various embodiments, monitoring the GC-PDCCH may include using the GC-RNTI and / or CORSET to monitor the TAC for the group of WTRUs.

[0094] In various embodiments, a method for and / or used in connection with performing network access to an NTN and / or performing other procedures in the NTN may be performed in a WTRU and may include autonomously adjusting a TA in the WTRU based on any of satellite ephemeris, network-sent control timing and data, and GNSS information. In various embodiments, the method may include the WTRU indicating its TA estimation capability to the network. In various embodiments, the method may include the WTRU indicating its capability to adjust the TA to the network. In various embodiments, a WTRU (e.g., UE) capability message may be used to indicate the WTRU's TA estimation capability to the network. In various embodiments, a WTRU (e.g., UE) capability message may be used to indicate the WTRU's capability to adjust the TA to the network.

[0095] In various embodiments, a method for and / or used in connection with performing network access to an NTN and / or performing other procedures in an NTN may be performed in a WTRU and may include indicating to the network either the WTRU's TA estimation capability or the WTRU's capability to adjust the TA. In various embodiments, a WTRU (e.g., UE) capability message may be used to indicate to the network the WTRU's TA estimation capability. In various embodiments, a WTRU (e.g., UE) capability message may be used to indicate to the network the WTRU's capability to adjust the TA.

[0096] In various embodiments, a method for and / or used in connection with performing network access to an NTN and / or performing other procedures in the NTN may be performed in a WTRU and may include determining a TAC mode to use based on information from the network. In various embodiments, the TAC mode may indicate a reference timing for the TAC.

[0097] In various embodiments, the TAC mode may be an autonomous mode or a non-autonomous mode. In various embodiments, in an autonomous TAC mode, the method may include the WTRU adjusting the TA based on a reference timing from either a previous UL transmission or a previous successful transmission. In various embodiments, in a non-autonomous TAC mode, the method may include the WTRU adjusting the TA based on a reference timing from a previous TAC. In various embodiments, the method may include receiving the TAC mode in any of L1, L2, and L3 signaling. In various embodiments, the WTRU may be dynamically informed of the TAC mode in each TAC message. In various embodiments, the WTRU may receive the TAC mode through any of MAC CE and RRC messages.

[0098] In various embodiments, a method for and / or used in conjunction with performing network access to the NTN and / or performing other procedures in the NTN may include a method for reducing an initial access time of a WTRU to the NTN. In various embodiments, the method may be performed in a WTRU and may include transmitting any of a number of preambles (Msg1) before receiving a random access response (Msg2) from the network. In various embodiments, the method may be performed in a WTRU and may include determining whether to perform a two-step random access channel (RACH) procedure or a four-step RACH procedure, and based on the determination, either performing a two-step RACH or a four-step RACH procedure. In various embodiments, the method may be performed in a WTRU and may include performing both a two-step and a four-step RACH procedure before monitoring for a random access response (RAR).

[0099] FIG. 2 illustrates an example four-step initial access procedure 200. The four-step initial access procedure 200 may be applicable to NR and NTN, for example. According to the four-step initial access procedure 200, the WTRU 102 may receive and read a Master Information Block (MIB) (not shown) and / or a System Information Block-1 (SIB1) (201). The WTRU 102 may perform DL synchronization using information obtained from and / or indicated by the MIB and / or SIB1 ("M / SIB information"). The WTRU 102 may determine, for example, via the SIB information, resources to be used to transmit a RACH preamble (Msg1) to the network to indicate its intent to access the network. The WTRU 102 may transmit Msg1 using such resources (203). The WTRU 102 may monitor a random access response (RAR) from the network in an RAR window.

[0100] If the network receives Msg1 correctly, it (e.g., a gNB) may send an RAR ("Msg2") to the WTRU (205). Msg2 may be scrambled with the RA-RNTI. The WTRU 102 may calculate the RA-RNTI as a function of the time and frequency of the resources used to transmit Msg1.

[0101] The WTRU 102 may receive Msg2 (205) from the gNB and descramble the message with the RA-RNTI. Msg2 may include any of the following: a timing advance (TA), a power adjustment / correction, a temporary cell radio network temporary identifier (TC-RNTI), and resources (grant) for the WTRU 102 to be used by the WTRU 102 to send a radio resource control (RRC) connection request ("Msg3").

[0102] The WTRU 102 may send its identification and initial access establishment (Msg3) to the network using the resources scheduled and granted in Msg2 (207). The network may inform the WTRU 102 of the completion of the initial access procedure with a contention resolution message ("Msg4") (209). Alternatively, the WTRU 102 may determine that the initial access procedure has failed if the WTRU 102 does not receive Msg4.

[0103] Although the four-step initial access procedure 200 is applicable to NR and NTN, such procedure 200 can be adapted to the differences between NR and NTN. Alternatively, modifying the procedure 200 adapted for NR for NTN (or vice versa) is not straightforward due to various differences between NTN and NR, including the long round trip time (RTT) between the WTRU 102 and the network, and the possibility of supporting large cell sizes (e.g., cell radii up to 1000 km) with the integration of NTN.

[0104] The transmission delay in NR may be very small and negligible compared to other delays due to processing times. The result of the slight transmission delay in NR is that when the WTRU 102 receives MIB and / or SIB1, it can determine the transmission slot of the DL signal and then identify the resources used to transmit Msg1 and the time (RAR window) to monitor Msg2 at / during, which are indicated in / by SIB1.

[0105] Due to long RTTs in the NTN, performing the NR-adapted initial access procedure 200 as an initial access procedure for an integrated NTN may result in ambiguity in the resources used for such a procedure. For example, the WTRU 102 may not be able to accurately identify the resources used to transmit Msg1 and / or the time for monitoring Msg2 (RAR window) because the timing for Msg1 and Msg2 may vary based on the RTT experienced by the WTRU. Similarly, due to RTTs and Doppler shifts, the network may determine that Msg1 was received on a different resource than the resource actually used by the WTRU 102, and may therefore miscalculate or otherwise determine the RA-RNTI for scrambling Msg2, potentially transmitting an incorrectly scrambled Msg2 and / or failing to transmit Msg2 in the expected time frame (RAR window). If the network uses one value for the RA-RNTI to scramble Msg2 and the WTRU 102 uses a different value for the RA-RNTI to descramble Msg2, the WTRU 102 may not receive and / or be unable to decode Msg2, which may result in a failure of the initial access procedure.

[0106] NTN satellites can move at up to 7 km / s (e.g., in low earth orbit (LEO)). Depending on the relative positions of the WTRU and the satellites, signals sent between the WTRU and the gNB may have significantly shifted receive / transmit frequencies, which may not be beneficial to the WTRU and gNB for the decoding process. Doppler shift pre-compensation may be implemented in various embodiments. To help the WTRU implement Doppler pre-compensation, information such as satellite velocity and position may be exchanged between the WTRU and the network.

[0107] In an NTN, the WTRU may need to wait a very long time between Msg1 and Msg2. In an NTN, it may be beneficial to apply a two-step RACH procedure. A two-step RACH procedure is considered, in which Msg1 and Msg3 are combined as MsgA, and Msg2 and Msg4 are combined as MsgB.

[0108] Various four-step RACH procedures for NTNs are similarly contemplated and may be beneficial in various ways, including, for example, maximizing access probability and / or minimizing delay (e.g., latency).

[0109] In an embodiment, the WTRU may determine the system frame number (SFN) of the NTN based on various information, which may include any of Global Navigation Satellite System (GNSS) timing, M / SIB1 information, and an offset.

[0110] In an embodiment, the WTRU may determine the DL transmission timing according to any of the following information received from the NTN: (i) the time offset T between the GNSS time and the DL SFN0; offset ,(ii) The timing offset between GNSS time and the time information indicated by the SIB1 information.

[0111] In an embodiment, the network determines the time offset T between its SFN and the GNSS time. offset It can be shown that T offset The value of can be sent by the MIB and / or SIB1 to assist the WTRU in the initial access procedure. The WTRU can determine the DL transmission time and RTT by the network by comparing the time it received the SIBI with the time information indicated in / by the SIBI information. For example, the WTRU can use the WTRU GNSS time (e.g., locally determined) and the T indicated in the M / SIB information to determine the DL transmission time and RTT by the network. offsetBy using the value, the time frame of the network can be determined. After decoding the timing information in the M / SIB information, the WTRU can determine the exact time when the network transmitted SIB1 and the time delay for transmitting SIB1.

[0112] In an embodiment, the WTRU may send its estimated timing based on the PRACH preamble and / or resource selection to the network.

[0113] In an embodiment, the WTRU may send TA information to the network to support the network in the scheduling of Msg3 and / or in further scheduling. The WTRU may send the TA information implicitly. The WTRU may send, for example, the RTT, the transmission delay, and an offset between the RTT or the transmission delay and a predefined value.

[0114] The predefined values ​​may be sent to the WTRU via the MIB and / or SIB, or may be preconfigured based on the satellite type.

[0115] The WTRU may send TA information to the network implicitly in Msg1. For example, the WTRU may send the TA information by selecting any of the PRACH resource, PRACH group, PRACH format, and PRACH configuration.

[0116] In an embodiment, the WTRU may be configured with multiple PRACH resources (eg, time and frequency) for transmitting Msg1. Each PRACH resource may be associated with a range of TA.

[0117] In an embodiment, the WTRU may be configured with multiple PRACH preamble groups. Each PRACH preamble group may correspond to a range of TA. Based on the estimated TA value, the WTRU may select an appropriate PRACH resource and / or PRACH preamble group. The WTRU may also select a default preamble group and / or resource, e.g., if TA information is not carried in Msg1. Using this approach may support non-GNSS WTRUs that may not have information about TA between the network and itself.

[0118] In an embodiment, a WTRU may be configured (e.g., statically, semi-statically, and / or dynamically) with one or more PRACH configurations. Any of the PRACH configurations may define, indicate, and / or include a preamble format and / or a period of PRACH opportunity ("PRACH-opportunity period"). The preamble format may define, indicate, and / or include any of the length of the preamble sequence, the number of repetitions, the cyclic prefix, the guard period, etc. The PRACH-opportunity period may define, indicate, and / or include the time between two consecutive PRACH opportunities.

[0119] In an embodiment, the WTRU may select a PRACH configuration based on its capabilities and information provided in / by the M / SIB information. In an embodiment, the WTRU may select a PRACH configuration to transmit Msg1 based on any of the following: whether the WTRU is a GNSS-based WTRU, the satellite type, the minimum delay of transmission, the maximum delay of transmission, the priority level of the WTRU, the QoS of the data in the buffer of the medium access control (MAC) layer, the Doppler compensation capability, and the TA of the WTRU (e.g., an estimate of the TA).

[0120] In an embodiment, the WTRU may select one or more of the PRACH configurations depending on its ability to estimate the transmission delay. For example, if it is not equipped with a GNSS receiver and / or may not (e.g., cannot) accurately estimate the transmission delay, the WTRU may select a PRACH configuration with a longer sequence length and / or a higher number of repetitions. Alternatively, for example, if it is equipped with GNSS and can accurately estimate the transmission delay, the WTRU may select a PRACH configuration with a shorter sequence length and / or a lower number of sequence repetitions.

[0121] In an embodiment, the WTRU may select a preamble group based on the location of the PRACH resource. In an embodiment, the WTRU may select different preamble groups based on the location of the PRACH resource within a delay difference period. The delay difference period may be defined as the maximum delay difference within a beam, may be based on the maximum delay difference within a beam, may be a function of the maximum delay difference within a beam, etc. This approach may help the network determine the PRACH resource used by the WTRU to transmit Msg1 because the WTRU may not have the exact timing of the uplink frame. By selecting PRACH resources in the same group for different PRACH time resources, the network and the WTRU may interpret the PRACH time resources differently. As a result, the WTRU may fail to decode the control resource set (CORESET) for Msg2.

[0122] In an embodiment, a WTRU may select a PRACH configuration with a longer sequence length and / or a higher number of repetitions if it is a high priority WTRU and / or if it has high QoS requirements for data in the MAC layer buffer. In an embodiment, if a WTRU is a low priority WTRU, it may select a PRACH configuration with a shorter sequence length and / or a lower number of sequence repetitions.

[0123] In an embodiment, the WTRU may determine the differential delay period based on (such as as a function of) any of the following preconfigured values ​​based on the maximum differential delay in a beam, a PRACH configuration period, a synchronization signal block (SSB) period, and a satellite type.

[0124] In an embodiment, the maximum differential delay within a beam may be conveyed by the network to the WTRU via the MIB and / or SIB1. In an embodiment, the PRACH configuration period may be signaled to the WTRU via SIB1. In an embodiment, the synchronization signal block (SSB) period may be pre-configured or signaled to the WTRU via SIB1. In an embodiment, the start of the differential delay period may be determined based on the time the WTRU receives SIB1 or the first opportunity for PRACH resources.

[0125] In an embodiment, the WTRU may determine the number of preamble groups N_pg based on any of the number of PRACH resources within the delay difference period, the number of PRACH times within the delay difference period, and the number of PRACH frequencies within the delay difference period.

[0126] The number of preambles in a preamble group can be equal for different preamble loops. The mapping between the PRACH resources and the preamble groups can follow a predefined rule of indexing the preamble groups and indexing the PRACH resources. The indexing of the PRACH resources can follow a time and frequency order consecutively or can follow a frequency and time order.

[0127] 3 is a system resource (time and frequency) diagram 300 illustrating an example allocation of preamble groups to SSBs ("Preamble Group Allocation"). As shown, the resource diagram 300 includes a first (in time) SSB 301 nfollowed by a second (in time) SSB301 n+1 3, and SSB 301n is followed by a first preamble group 305-1, a second preamble group 305-2, a first differential delay period 307-1, and a second differential delay period 307-2. n , SSB301 n+1 A PRACH selection window may be included after each of the

[0128] Referring to FIG. 3, the WTRU 102 includes an SSB 301 n It can also detect SSB301 n 1. Based on reading the information from SIB1, the WTRU 102 can obtain the PRACH configuration indicated by SIB1. The WTRU 102 can divide the PRACH selection window into one or more differential delay periods. The WTRU can determine two possible times for transmitting Msg1 within the differential delay period. The WTRU can determine the number of preamble groups based on the number of possible PRACH times within the differential delay period. Because there are two possible times for transmitting Msg1 within the differential delay period, the WTRU can divide the set of preambles into two equal sized preamble groups, i.e., first and second preamble groups 305-1, 305-2. As shown, the first preamble group 305-1 can be assigned to a first possible time for PRACH transmission, and the second preamble group 305-2 can be assigned to a second possible time for PRACH transmission. If the number of PRACH preambles assigned to an SSB is N_preambles, then the size of each PRACH group is N_preambles / N_pg. When applied to the example of FIG. 3, where N_pg=2, and N_preambles=64, 32 of the 64 (i.e., 64 / 2=32) preambles are assigned to each of the first and second PRACH preamble groups.

[0129] In an embodiment, the WTRU may be configured to select one or more preamble groups based on the location of the PRACH resource within the differential delay period and its associated SSB. This approach allows the WTRU to signal to the network with its intended SSB if multiple SSBs are supported.

[0130] In an embodiment, the WTRU may be configured to have access to all possible PRACH opportunities. The WTRU may be configured to determine the total number of PRACH preambles assigned to itself by dividing the total number of preambles assigned to each PRACH opportunity by the total number of SSBs. The first index associated with the SSB and PRACH opportunity may be calculated based on the index of the intended SSB and the position of the PRACH opportunity. The WTRU may be configured to inform the network of the intended SSB.

[0131] In an embodiment, the WTRU may select its PRACH opportunity and PRACH group based on its associated SSB and its selected PRACH opportunity in the differential delay period, respectively. As an example, the WTRU may be configured to sequentially associate PRACH opportunities with SSBs. And for every PRACH opportunity, the WTRU may be configured to select a different preamble group based on the time of the PRACH resource within the differential delay period.

[0132] 4 is a system resource (time and frequency) diagram 400 illustrating an example preamble group allocation for an SSB set. As shown, the resource diagram 400 may include an SSB set 401, a first preamble group 405-1, a second preamble group 405-2, a first differential delay period 407-1, and a second differential delay period 407-2. Although not shown, the resource diagram 400 may include a third differential delay period after the second differential delay period, a PRACH selection window after each of the instances of the SSB set 401.

[0133] Referring to FIG. 4, the SSB set 401 may include a first and a second SSB 401-1, 401-2. The total number of PRACH time instances associated with the two SSBs may be equal to six (e.g., as shown). The WTRU may associate the first SSB 401-1 with three PRACH time instances and the second SSB 401-2 with three PRACH time instances. The WTRU may divide the PRACH selection window into one or more differential delay periods. The WTRU may select any of the possible PRACH time instances associated with the selected one SSB 401-1, 401-2. The WTRU may select one PRACH opportunity in one PRACH time instance to transmit Msg1. Based on the time instance of the selected PRACH opportunity that falls within one of the differential delay periods 407-1, 407-2, the WTRU may select either the first preamble group 405-1 or the second preamble group 405-2.

[0134] In an embodiment, the WTRU 102 may select a preamble group and a preamble within the group based on the selected differential delay period. In an embodiment, the WTRU 102 may be configured with a set of preambles. The WTRU 102 may divide its PRACH selection window into one or more differential delay periods, where each period may be associated with one preamble group. When the WTRU 102 selects a PRACH position for transmitting Msg1, depending on the selected differential delay period, the WTRU may select an appropriate preamble.

[0135] 5 is a system resource (time and frequency) diagram 500 illustrating an example preamble group allocation for a PRACH selection window. As shown, the resource diagram 500 includes a second (in time) SSB 501 n+1 The first (in time) SSB501 followed byn , SSB501 n The PRACH selection window 503 after the SSB 501, the first preamble group 505-1, the second preamble group 505-2, the first differential delay period 507-1, the second differential delay period 507-2, and the third differential delay period 507-3. n+1 A PRACH selection window may be included after the

[0136] 5, the WTRU 102 may divide the PRACH selection window into three differential delay periods: If the WTRU transmits Msg1 in differential delay period 507-1 and differential delay period 507-3, the WTRU 102 may select the first preamble group 505-1; if the WTRU 102 selects differential delay period 507-2 instead, it may select preamble group 505-2.

[0137] In an embodiment, the WTRU 105 may select a preamble group based on the selected SSB and differential delay period. For example, the WTRU 102 may sequentially associate PRACH opportunities with SSBs, and for every PRACH opportunity, the WTRU may select a different preamble group based on its selected differential delay period.

[0138] 6 is a system resource (time and frequency) diagram 600 illustrating an example preamble group allocation for an SSB set. As shown, the resource diagram 600 may include an SSB set 601, a first preamble group 605-1, a second preamble group 605-2, a first differential delay period 607-1, and a second differential delay period 607-2. Although not shown, the resource diagram 600 may include a third differential delay period after the second differential delay period, and a PRACH selection window after each instance of the SSB set 601.

[0139] Referring to FIG. 6, the SSB set 601 may include a first and a second SSB 601-1, 601-2. The number of PRACH time instances associated with the two SSBs 601-1, 601-2 is equal to six (e.g., as shown). The WTRU 102 may associate the first SSB 601-1 with three PRACH time instances and the second SSB 601-2 with three PRACH time instances. The WTRU 102 may divide the PRACH selection window into one or more differential delay periods. The WTRU 102 may select any of the PRACH time instances associated with the selected one SSB 601-1, 601-2. The WTRU 102 may select one PRACH opportunity to send Msg1. Based on which of the differential delay periods 607-1, 607-2 includes the selected PRACH opportunity, the WTRU 102 may select the first preamble group 605-1 or the second preamble group 605-2.

[0140] In an embodiment, the WTRU may be configured to select a different frequency for transmitting Msg1 based on its PRACH transmission time within the differential delay period. This approach may avoid misunderstandings between the network and the WTRU in the calculation of the RA-RNTI. The initial frequency for the PRACH may be conveyed to the WTRU via SIB1. Based on the time index of the PRACH opportunity within the differential delay period, the WTRU may determine the frequency for transmitting Msg1. This frequency may be determined as f=finit+PRACHindex*Δf, where finit is the initial frequency of the PRACH indicated by / in SIB1, and Δf is the frequency resource for each PRACH.

[0141] 7 is a system resource (time and frequency) diagram 700 illustrating an example preamble group allocation. As shown, the resource diagram 700 includes a first (in time) SSB 701 n followed by a second (in time) SSB701 n+1followed by six PRAH resources 711-1 to 711-6, a first differential delay period 707-1, and a second differential delay period 707-2.

[0142] 7, the WTRU 102 may be configured to have three PRACH transmission times within at least a first differential delay period 707-1. Based on a time index within the differential delay period 707-1, the WTRU 102 may select an appropriate frequency for transmitting Msg1. Selecting a different frequency for each PRACH transmission time within the differential delay period allows the gNB to identify the time resource that the WTRU uses for the PRACH transmission.

[0143] 8 is a flow diagram illustrating an example procedure for performing preamble group assignment ("preamble group assignment procedure") 800. For ease of explanation and simplicity, the preamble group assignment procedure 800 is from the perspective of the WTRU 102. Those skilled in the art will appreciate that the preamble group assignment procedure 800 may be performed with other or different system resources than those disclosed herein and / or with other or different perspectives and architectures.

[0144] The WTRU 102 may receive differential delay information and PRACH configuration information (801). The differential delay information and PRACH configuration information may be received from a network element of the NTN. The PRACH configuration information may indicate a set of preambles and a PRACH opportunity configuration. The differential delay information may be and / or may include a maximum delay difference.

[0145] The WTRU 102 may determine a set of candidate PRACH opportunities from among the multiple PRACH opportunities of the PRACH opportunity configuration based on the differential delay information (803). The WTRU 102 may select a preamble from a preamble group assigned to a candidate PRACH opportunity of the set of candidate PRACH opportunities (805). The WTRU 102 may transmit the selected preamble using a RACH resource corresponding to the one candidate PRACH opportunity (807).

[0146] In various embodiments, the WTRU 102 may determine the set of candidate PRACH opportunities, at least in part, by determining a set of candidate PRACH opportunities that are within a differential delay period from among multiple PRACH opportunities of the PRACH opportunity configuration. In various embodiments, the WTRU 102 may determine the number of preamble groups based on the number of PRACH resources included in the differential delay period.

[0147] In various embodiments, the WTRU 102 may assign a preamble group (e.g., one of a plurality of preamble groups) to a candidate PRACH opportunity. In various embodiments, the WTRU 102 may assign a preamble group to a candidate PRACH opportunity based on a rule. In various embodiments, the rule may specify that a partition of a set of preambles is to be assigned. In various embodiments, the preamble group may be assigned to a candidate PRACH opportunity based on a configured mapping. In various embodiments, the preamble group may be a subset of the set of preambles. In various embodiments, the WTRU 102 may assign each group of preambles to a candidate PRACH opportunity.

[0148] In various embodiments, the WTRU 102 may randomly select one candidate PRACH opportunity from among the set of candidate PRACH opportunities. In various embodiments, the WTRU 102 may determine one candidate PRACH opportunity from among the set of candidate PRACH opportunities based on a preamble group assigned to one candidate PRACH opportunity that includes a preamble having a particular characteristic. In various embodiments, the WTRU 102 may determine one candidate PRACH opportunity from among the set of candidate PRACH opportunities based on a second group of preambles assigned to another candidate PRACH opportunity that lacks a preamble lacking a particular characteristic.

[0149] 9 is a flow diagram illustrating an example preamble group allocation procedure 900. For ease of explanation and simplicity, the preamble group allocation procedure 900 is from the perspective of the WTRU 102. Those skilled in the art will appreciate that the preamble group allocation procedure 900 may be performed with other or different system resources than those disclosed herein and / or with other or different perspectives and architectures.

[0150] The WTRU 102 may receive differential delay information and PRACH configuration information (901). The differential delay information and PRACH configuration information may be received from a network element of the NTN. The PRACH configuration information may indicate a set of preambles and a PRACH opportunity configuration. The differential delay information may be and / or include a maximum delay difference.

[0151] The WTRU 102 may determine a delay difference period based on the differential delay information (903). The WTRU 102 may determine a set of candidate PRACH opportunities for the PRACH opportunity configuration based on the delay difference period (905). The WTRU 102 may assign a preamble group to each candidate PRACH opportunity in the set of candidate PRACH opportunities (907). The WTRU 102 may select a preamble from the preamble group assigned to a candidate PRACH opportunity in the set of candidate PRACH opportunities (909). The WTRU 102 may transmit the selected preamble using a PRACH resource corresponding to one candidate PRACH opportunity (911).

[0152] The preamble group allocation procedure 900 of Figure 9 is similar to the preamble group allocation procedure 800 of Figure 8. Those skilled in the art will appreciate that the various embodiments disclosed in relation to the preamble group allocation procedure 800 of Figure 8 are equally applicable as various embodiments of the preamble group allocation procedure 900 of Figure 9. In addition, those skilled in the art will appreciate that the various embodiments disclosed below are embodiments applicable to both the preamble group allocation procedures 800 and 900.

[0153] In various embodiments, the WTRU 102 may determine a candidate PRACH opportunity from among a set of candidate PRACH opportunities based on a group of preambles assigned to the candidate PRACH opportunity that corresponds to a range of timing advance between the WTRU and the network.

[0154] In various embodiments, the set of candidate PRACH opportunities may be associated with an SSB. In various embodiments, the WTRU 102 may inform the network of the estimated TA.

[0155] In various embodiments, the WTRU 102 may select at least one frequency resource to transmit the selected preamble. In various embodiments, the WTRU 102 may select a PRACH resource corresponding to a candidate PRACH opportunity based on network configured frequency hopping and may transmit the selected preamble using the PRACH resource.

[0156] In various embodiments, the WTRU 102 may determine the RA-RNTI based on the PRACH resource. In various embodiments, the WTRU 102 may decode Msg2 with the determined RA-RNTI.

[0157] In an embodiment, the WTRU may perform Doppler pre-compensation based on a velocity vector sent by the network. In an embodiment, the WTRU may be configured to perform Doppler pre-compensation by using information received from the network and / or information estimated by and / or pre-configured in the WTRU. The information received from the network may include, for example, the velocity vector, and maximum and / or minimum distance. The information estimated by and / or pre-configured in the WTRU may include, for example, the TA, and satellite ephemeris.

[0158] In an embodiment, the WTRU may receive Doppler shift compensation information (e.g., a Doppler shift compensation command, other trigger information, etc.) from a gNB (or other access node). The WTRU may perform Doppler pre-compensation after receiving (e.g., in response to receiving) the Doppler shift compensation information. The WTRU may receive the Doppler shift compensation information from the gNB in ​​either Layer 1 (L1), Layer 2 (L2), or Layer 3 (L3) signaling, such as, for example, a MAC Control Element (CE) or a Radio Resource Control (RRC) message. The WTRU may adjust the Doppler shift pre-compensation after receiving (e.g., in response to receiving) the Doppler shift compensation information, possibly using a previous pre-compensated Doppler shift from the gNB and / or a pre-compensated Doppler shift from a last UL transmission as a reference. The Doppler shift pre-compensation approach may assist in reducing inter-frequency interference in variously scheduled resources.

[0159] In accordance with various embodiments disclosed herein, the RA-RNTI may be determined in various manners. In an embodiment, the WTRU may determine the RA-RNTI based on a selected PRACH configuration. In an embodiment, the WTRU may calculate the RA-RNTI by using the time and frequency index of the PRACH opportunity. This approach may reduce the number of RA-RNTIs used. In an embodiment, the WTRU may follow the following formula for the RA-RNTI: RA-RNTI=C+t index +X*f index (1) where C is a constant and t index , f index where X is the time and frequency index of the PRACH opportunity, and X may be determined based on any of the following:

[0160] X is based on the maximum time and frequency index of all possible PRACH configurations.

[0161] X is based on the maximum time and frequency index of the current PRACH configuration.

[0162] X is pre-configured.

[0163] In an embodiment, the RA-RNTI may be calculated as follows: RA-RNTI=C+f index +Y*t index (2) where C is a constant and t index , f index is the time and frequency index of the PRACH opportunity, and Y may be determined based on any combination of the following:

[0164] Y is based on the maximum time and frequency index of all possible PRACH configurations.

[0165] Y is based on the maximum time and frequency index of the current PRACH configuration.

[0166] Y is pre-configured.

[0167] According to an embodiment, the WTRU may determine an initial frame for time indexing.

[0168] The WTRU will determine which RAR Window F the network wants to support. R Based on the duration of t index or for the calculation of the RA-RNTI. In an embodiment, the frame index at which the WTRU transmits Msg1 may be calculated as follows:

[0169]

number

[0170] During the ceremony, PRACH frameindicates the SFNs on which the WTRU can transmit Msg1. index The initial frame for indexing of the SFN and / or the initial frame for calculation of the RA-RNTI is the frame before the current SFN. index It can be determined that the time is -1 frame.

[0171] In an embodiment, the WTRU may determine the time index of its selected PRACH location.

[0172] In an embodiment, the WTRU may determine the time index of every PRACH time opportunity. This approach may be interesting if the network and the WTRU have a common understanding of the intended PRACH location that the WTRU sent.

[0173] In an embodiment, the WTRU may determine the time index of every differential delay period. This approach allows the network to group all Msg1 transmissions at one frequency and within a differential delay period into one RA-RNTI value. For example, as shown in Figure 10, each differential delay period consists of two PRACH time instances. Therefore, two PRACH time instances within one differential delay period have the same index.

[0174] In another approach, the WTRU may be configured to decode Msg2 using multiple RA-RNTIs within the delay difference period. Specifically, the WTRU may determine the number of PRACH time instances within the delay difference period at which it transmits Msg1. The WTRU may then calculate all possible RA-RNTIs within the delay difference period. These RA-RNTIs may be used to descramble Msg2 during the random access response period. This approach allows the WTRU to take into account the delay difference of WTRUs served by one SSB.

[0175] According to various embodiments disclosed herein, a reduction in delays contributing to the amount of time to perform an initial access procedure and / or an increase in the access probability (e.g., fewer unsuccessful access attempts) may be achieved. In an embodiment, the WTRU may transmit multiple Msg1 transmissions before receiving Msg2. In an embodiment, the WTRU may determine to transmit N Msg1s before each RACH opportunity, and the WTRU may transmit such N Msg1s over M RACH opportunities. The WTRU may apply various (e.g., different) power adjustments for the various transmissions of Msg1. The power adjustments may be determined based on assumptions regarding the PRACH location and / or the delay between the WTRU and the network. This allows the WTRU to adjust the transmit power of Msg1 if different delays are assumed by the WTRU.

[0176] The WTRU may be configured with a maximum value for M and N. The values ​​of M and N within the configuration range may be determined based on any of the following: the WTRU's capabilities in estimating delay, the minimum and / or maximum delay of a transmission, the QoS of the data, the priority level of the WTRU, the number of applicable PRACH sequences, and the configuration of the PRACH.

[0177] In an embodiment, the WTRU may transmit one Msg1 in one PRACH occasion if the transmission delay can be accurately estimated, which can be obtained by using GNSS information, or, for example, as shown in FIG. 11, the WTRU may transmit several Msg1s before one PRACH occasion and across multiple PRACH occasions if the transmission delay is not accurately estimated by the WTRU.

[0178] In an embodiment, the WTRU may determine whether to perform a two-step or a four-step RACH procedure based on any of the following: whether the WTRU is a GNSS-based WTRU, i.e., a satellite type that can be targeted and / or accessed, minimum transmission delay, maximum transmission delay, QoS of the data, priority level of the WTRU, number of available PRACH sequences, configuration of the PRACH, Doppler compensation function, and size of Msg3.

[0179] In an embodiment, assuming it is equipped with a GNSS receiver and appropriate processing, the WTRU may perform a two-step RACH procedure if it can accurately determine the timing and data of the PRACH opportunity. In an embodiment, the WTRU may perform a four-step RACH procedure if it cannot accurately estimate the transmission delay. Forgoing the two-step RACH procedure if the WTRU cannot accurately estimate the transmission delay may increase the probability that the two-step RACH procedure will be successful, as it may avoid a situation where the WTRU does not have accurate timing for the data transmission and the network may then be unable to accurately receive and / or decode the transmitted data.

[0180] In an embodiment, a WTRU may perform a two-step RACH if it is a high priority WTRU and / or if it has high QoS data in its data buffer. In an embodiment, a WTRU may perform a four-step RACH if it is a low priority WTRU and / or if it has low QoS data in its buffer. Not using a two-step RACH procedure if the WTRU is a low priority WTRU and / or if it has low QoS data in its buffer allows prioritization of high priority WTRUs in accessing the network during the initial access procedure and allows data resources dedicated to high priority WTRUs to be used to avoid low priority WTRUs.

[0181] In an embodiment, the WTRU may perform two-step and four-step RACH procedures before monitoring the RAR. For example, the WTRU may perform both two-step and four-step RACH procedures by sending one Msg1 and one MsgA, where Msg1 is for a RACH opportunity according to a four-step RACH configuration and MsgA is sent in a RACH opportunity according to a two-step RACH configuration. The WTRU may decide to perform both two-step and four-step RACH procedures based on any of the following: whether the WTRU is a GNSS-based WTRU, the minimum transmission delay, the maximum transmission delay, the QoS of the data, the priority level of the WTRU, the number of available PRACH sequences, the PRACH configuration, the Doppler compensation function, and the size of Msg3.

[0182] In an embodiment, the WTRU may determine a RACH configuration to transmit any of a variety of messages, such as, for example, MsgA. In an embodiment, the WTRU may be configured with various parameters from which to select for a RACH configuration for transmitting MsgA. Such parameters may include, for example, any of a preamble index, a resource for preamble transmission, a number of preamble transmissions, a resource for PUSCH in MsgA, a number of PUSCH transmissions, a redundancy version (RV) sequence, an association between the preamble and PUSCH, a transmit power for the PUSCH (e.g., a maximum transmit power, a calculated transmit power, etc.), and / or a modulation and coding scheme (MCS) for the PUSCH.

[0183] In an embodiment, any of a variety of parameters may be selected based on one or a combination of factors, such as, for example, any of the following: type of WTRU, class of WTRU, whether the WTRU is equipped with GNSS capability, whether the WTRU has the capability to estimate TA, position, etc. (e.g., whether certain capabilities exist and / or are sufficient to provide an accurate estimation), Doppler compensation capability, size of the MsgA (e.g., number of bits), estimated TA, and predicted TA.

[0184] In an embodiment, the WTRU may determine the number of PUSCHs and / or the number of preamble transmissions based on the estimated TA and / or the accuracy of the estimated TA. As an example, the WTRU may determine (and use) to use one preamble and one or more PUSCH transmissions based (e.g., conditioned) on the WTRU having the capability to and / or be able to accurately estimate the TA. In another example, the WTRU may determine (and use) to use one preamble with multiple PUSCH transmissions based (e.g., conditioned) on the WTRU not having the capability to and / or be able to accurately estimate the TA. In another example, the WTRU may determine (and use) to use multiple preambles with one PUSCH transmission based (e.g., conditioned) on the WTRU not having the capability to and / or be able to accurately estimate the TA. In yet another example, the WTRU may decide to (and may use) multiple transmissions of both the preamble and PUSCH based on (e.g., conditioned on) the WTRU not having the capability and / or being unable to accurately estimate the TA.

[0185] Although the parameters and factors in the above examples refer to the number of preambles and / or the number of PUSCH transmissions in conjunction with the estimated TA, the WTRU may use parameters and factors other than the number of preambles, the number of PUSCH transmissions, and the estimated TA to determine the RACH configuration for transmitting MsgA. For example, the WTRU may determine the MCS of the PUSCH based on the estimated TA. The WTRU may determine to use a relatively small MCS index in the MCS table if the estimated TA is relatively large, and may determine to use a relatively large MCS index if the estimated TA is relatively small. In another example, the WTRU may determine the transmit power of the PUSCH based on the estimated TA. The WTRU may determine to use a relatively high power if the estimated TA is relatively high, and may determine to use a relatively low power if the estimated TA is relatively low.

[0186] In an embodiment, the WTRU may indicate (or report) its estimated TA to the network. The WTRU may inform the network of the estimated TA, e.g., using MsgA. Informing the network of the estimated TA may provide various benefits including, e.g., being able to support the gNB in ​​scheduling HARQ ACK / NACKs for MsgB and / or in scenarios where MsgA is not successfully decoded.

[0187] The WTRU may explicitly and / or implicitly inform the network of the estimated TA. In an embodiment, the WTRU may include the estimated TA in the PUSCH of the MsgA. Alternatively, the WTRU may include an index to a table of estimated TAs in the PUSCH of the MsgA. The index may indicate, for example, one or more ranges of the estimated TA among multiple ranges in the table. In an embodiment, the WTRU may implicitly inform the network of its estimated TA by using a specific parameter or combination of parameters for the MsgA. For example, the WTRU may use a fixed preamble index (e.g., a fixed preamble resource), where the preamble index (e.g., the preamble resource) is associated with a range of the estimated TA. In another example, the WTRU may use a combination of a preamble index and a preamble resource, where the combination of a preamble index and a preamble resource is associated with a range of the estimated TA.

[0188] Although the parameters in the above examples refer to preamble index and preamble resource, the WTRU may implicitly inform the network of its estimated TA using parameters other than and / or in addition to the preamble index and preamble resource. For example, the WTRU may implicitly inform the network of its estimated TA using a selected preamble format, preamble route sequence, preamble cyclic prefix, etc.

[0189] In an embodiment, the WTRU may determine one or a combination of various transmission characteristics to be used for transmission and / or retransmission of MsgA. Some or all of the transmission characteristics may be based on the reception status of MsgB. The reception status of MsgB may be any of the following conditions:

[0190] There is no MsgB (eg, the WTRU does not receive PDCCH (scrambled with RA-RNTI) within the MsgB window).

[0191] Fail to decode MsgB (eg, the WTRU successfully decodes a PDCCH scrambled with RA-RNTI in the MsgB window, but fails to decode the corresponding PDSCH).

[0192] MsgB indicates an ACK for the preamble and a NACK for the PUSCH.

[0193] MsgB indicates a NACK for the preamble and an ACK for the PUSCH.

[0194] MsgB indicates ACK for both the preamble and the PUSCH.

[0195] Various transmission characteristics available for the WTRU to use may include any of the following: performing a power boost for the preamble, adjusting (e.g., increasing / decreasing) the transmit power, adjusting the MCS for the PUSCH (e.g., reducing / increasing the data rate), switching from a 2-step RACH to a 4-step RACH (e.g., transmitting only the preamble), adjusting (e.g., increasing / decreasing) the number of PUSCH transmissions, adjusting (e.g., increasing / decreasing) the number of preamble transmissions, adjusting the estimated TA value, using a different resource configuration for MsgA, selecting a particular preamble format, and using or switching to a different (e.g., different) preamble format.

[0196] As an example, the WTRU may increase the number of PUSCH and / or preamble transmissions based on (or conditional on) not receiving MsgB ("no MsgB" situation) and / or failing to decode MsgB ("fail to decode MsgB" situation). Increasing the number of PUSCH and / or preamble transmissions may provide various benefits including, for example, increasing the probability of reception of MsgA. Alternatively, the WTRU may use a different preamble format and / or a different resource configuration for the preamble transmissions in MsgA.

[0197] As previously disclosed herein, the WTRU may initiate an initial access procedure by sending Msg1 (e.g., a RACH preamble) to the network. In an embodiment, the WTRU may determine a transmit power TxP for Msg1, for example, based (at least in part) on various satellite information received from the network. The satellite information may include any of a target power information element (IE) at which the preamble is received, a power increase step IE, a satellite transmit power ("Sat Tx Power") IE, a satellite type IE, an altitude IE, a velocity IE, and an ephemeris data IE.

[0198] The target power IE at which the preamble is received may specify a receive target power (e.g., in dB) for each of one or more satellites. The power up step IE may specify one or more power up steps (e.g., each having a power with a sign indicating to increase or decrease by a specified power (e.g., in dB)) for each of one or more satellites.

[0199] The Sat Tx Power IE may specify, for each of one or more satellites, the power (e.g., in dB) for each of various signals transmitted from the associated satellite. The various signals may include reference signals, such as synchronization signals.

[0200] The satellite type IE may specify one or more satellite types, e.g., geostationary orbit (GEO), medium earth orbit (MEO), low earth orbit (LEO), high altitude pseudo satellite (HAPS), etc. The altitude IE may specify, for each of the one or more satellites, one or more altitudes of the associated satellite. The altitudes may include, for example, a current altitude, a past altitude, and a future altitude. The altitude IE may include different accuracy values ​​for some or all of the specified altitudes.

[0201] The velocity IE may specify, for each of one or more satellites, one or more velocities of the associated satellite. Each velocity may be specified as a velocity relative to the Earth. The velocities may include, for example, a current velocity, a past velocity, and a future velocity. The velocity IE may include different accuracy values ​​for some or all of the specified velocities.

[0202] The Ephemeris IE may specify, for each of one or more satellites, one or more ephemeris data for the associated satellite. The ephemeris data may include, for example, ephemeris data received from the associated satellite and / or long-term ephemeris data. The Ephemeris Data IE may include different accuracy values ​​for some or all of the specified ephemeris data.

[0203] The satellite information may be sent by the network and received by the WTRU (e.g., in one or more information elements (IEs) thereof) in any of Layer 1 (L1), Layer 2 (L2), and Layer 3 (L3) signaling. For example, the satellite information may be sent by the network and received by the WTRU in a dedicated SIB (or other IE) or in system information in either the MIB and / or one or more SIBs. As an example, the target power IE at which the preamble is received and the power up step IE may be sent by the network and received by the WTRU in SIB2, while the satellite type, altitude, velocity, and ephemeris data IEs may be sent by the network and received by the WTRU in the MIB and one or more other SIBs.

[0204] In an embodiment, the WTRU may determine a received power based on a reference signal. The determined received power may be, for example, a reference signal received power (RSRP). For ease of explanation, it is assumed below that the measured reference signal is a synchronization signal and the determined received power is the RSRP of the synchronization signal (herein "SS-RSRP").

[0205] In an embodiment, the WTRU may estimate the path loss (PL) based on (e.g., as a function of) the Sat Tx power IE and the SS-RSRP, for example, according to: PL=Sat Tx Power-SS-RSRP (4) The estimated PL may be valid at time t1 corresponding to when the synchronization signal was measured in connection with determining the SS-RSRP. However, due to mobility, satellite speed (especially for LEO satellites and the like), and other factors, the estimated PL may not reflect (e.g., may not accurately reflect) the PL between the WTRU and the satellite at time t2 when Msg1 is intended and / or expected to reach the satellite. Using a PL that reflects the PL between the WTRU and the satellite at time t2 may result in the transmit power TxP for Msg1 being set appropriately and may avoid unnecessary retransmissions of Msg1 and / or transmissions of other WTRUs (e.g., due to transmit power TxP for Msg1 causing interference).

[0206] In an embodiment, the WTRU may predict a PL at time t2 based on (e.g., with and / or as a function of) any of a calculated distance to an associated satellite at time t1, an estimated PL at time t1, and a predicted distance to the satellite at time t2 (the "predicted PL"). For example, the predicted PL may be based on a ratio of the calculated distance and the predicted distance applied to the estimated PL. In an embodiment, the WTRU may calculate its distance from the satellite at time t1 based on satellite information, such as, for example, the satellite altitude and ephemeris data IE. The WTRU may predict its distance from the satellite at time t2 based on (e.g., with) information such as the WTRU's orbit, the satellite altitude IE, velocity IE, and ephemeris data IE.

[0207] In an embodiment, the WTRU may calculate two transmit powers TxP1, TxP2. The first and second transmit powers TxP1, TxP2 may be based, for example, on the estimated PL and the predicted PL, respectively. The first and second transmit powers TxP1, TxP2 may be calculated, for example, as follows: TxP1(t1) = target power at which the preamble is received + PL(t1) (5) TxP2(t2) = target power at which the preamble is received + PL(t2) (6) where the target power at which the preamble is received may be obtained from satellite information, PL(t1) may be (or may be based on) an estimated PL, and PL(t2) may be (or may be based on) a predicted PL.

[0208] In an embodiment, the WTRU may determine a transmit power TxP for Msg1 based on the first and second transmit powers TxP1, TxP2. For example, the transmit power TxP for Msg1 may be the maximum of the first and second transmit powers TxP1, TxP2. Alternatively, the transmit power TxP for Msg1 may be the average of the first and second transmit powers TxP1, TxP2, or some other function.

[0209] In an embodiment, the WTRU may set and / or apply a transmit power, TxP, for Msg1 according to: TxP=min(maximum power, f(TxP1(t1), TxP2(t2))) (7) where max power may be the maximum transmit power, TxP1(t1) may be (or may be based on) the first transmit power TxP1, TxP2(t2) may be (or may be based on) the first transmit power TxP1, and f(TxP1(t1), TxP2(t2)) refers to some function applied to TxP1(t1) and / or TxP2(t2). The max power may be a configured maximum transmit power (e.g., configured using either L1, L2, or L3 signaling) and / or may be based on the WTRU class.

[0210] If an initial attempt to transmit Msg1 fails (e.g., no response from the satellite within the RAR window), the WTRU may modify (e.g., increase) the first transmit power TxP1 according to the power increase step IE. Alternatively and / or in addition, the WTRU may determine a third transmit power TxP3 for retransmitting Msg1 based on a second predicted PL between the WTRU and the satellite at time t3 when Msg1 is intended and / or predicted to reach the satellite after retransmission. The WTRU may predict the second predicted PL at time t3 based on (e.g., with and / or based on a function of) any of the calculated distance to the associated satellite at time t1, the estimated PL at time t1, and the predicted distance to the satellite at time t3. The WTRU may determine the transmit power TxP3 using Equation 6, except that PL(t2) is replaced with PL(t3), where PL(t3) may be (or be based on) the second predicted PL. For Msg1 retransmission, the WTRU may set and apply TxPower for Msg1 according to the following: TxP = min(max power, f(TxP(t1) + power increase step, TxP3(t3))) (8) where max power may be the maximum transmit power, TxP1(t1) may be (or may be based on) the first transmit power TxP1, TxP3(t3) may be (or may be based on) the third transmit power TxP3, and f(TxP(t1)+power increase step, TxP2(t2)) refers to some function applied to TxP(t1)+power increase step, TxP2(t2). Max power may be a configured maximum transmit power (e.g., configured using either L1, L2, or L3 signaling) and / or may be based on the WTRU class.

[0211] Although the above embodiments are described with respect to Msg1 transmissions and / or retransmissions, such embodiments are equally applicable to preamble transmissions and / or retransmissions and may be implemented accordingly.

[0212] In an embodiment, the WTRU may determine which synchronization raster (or any of several synchronization rasters) to use. The determination may be based on the satellite type the WTRU is targeting and / or accessing. In an embodiment, the WTRU may be configured with one or more synchronization rasters. Each (or any) of the synchronization rasters may be associated with one or more satellite types. The WTRU may determine which of the configured synchronization rasters to use based on the satellite type it is targeting. In an embodiment, the WTRU may be configured with a large raster for LEO satellites and a smaller (compared to LEO satellites) synchronization raster for GEO satellites. Configuring a large synchronization raster for LEO satellites may reduce the number of SSB frequency positions for the WTRU to access the satellites (e.g., to compensate for the high Doppler shift of LEO satellites).

[0213] In an embodiment, the WTRU can determine the SSB timing of multiple beams transmitted by the satellite, for example, based on the timing of one SSB in a beam and a timing pattern (e.g., a (pre)defined timing pattern). In an embodiment, the satellite can (pre)configure predefined timing patterns for multiple beams at the satellite. Based on the SSB timing of different beams, the WTRU can determine the times to monitor different frequencies to detect SSB from the beam at the satellite.

[0214] In an embodiment, a WTRU may monitor a group common PDCCH (GC-PDCCH) and may receive an indication of a Timing Advance (TA) Command (TAC) for itself and / or for a group of WTRUs ("group TAC").

[0215] In an embodiment, the WTRU may monitor the GC-PDCCH for the group TAC and adjust its timing advance to match that of the group TAC. In an embodiment, the WTRU may be configured with a GC-RNTI and CORSET to monitor the group TAC for the WTRU's group.

[0216] In an embodiment, the WTRU may autonomously adjust its TA. For example, the WTRU may autonomously determine (e.g., estimate) its TA based on any of the control and / or data timing, satellite ephemeris, and GNSS information sent from the network. The WTRU may receive, for example, a TA rate of change in the ephemeris to adjust its TA. Alternatively, the WTRU may estimate the TA based on the WTRU's position obtained from the GNSS information. In an embodiment, the WTRU may indicate its TA estimation capability to the network. In an embodiment, the UE may indicate its capability of TA adjustment to the network. The TA estimation capability and / or TA adjustment capability may be sent to the network in a WTRU (e.g., UE) capability message.

[0217] In an embodiment, the WTRU may determine the TAC mode to use based on information from the network (e.g., information provided by the gNB). In an embodiment, the gNB and / or the network may support one or more TAC modes for the WTRU. Each (or any) of the TAC modes may indicate a reference timing for the TAC. The TAC modes may include an autonomous mode and a non-autonomous mode. In an autonomous mode, the WTRU may measure the TA, and in a non-autonomous mode, the WTRU may not be able to measure the TA by itself. In an autonomous mode, the WTRU may change the TA based on a reference timing, for example, from its previous UL transmission, a previous successful transmission, and the like. In a non-autonomous mode, the WTRU may change the TA based on a reference timing, for example, from a previous TAC.

[0218] The WTRU may be informed of its TAC mode in any of the L1, L2, and L3 signaling. For example, the WTRU may be dynamically informed of the TAC mode in each TAC message. Alternatively, the WTRU may be semi-statically configured which TAC modes it can use based on any of the MAC CE and RRC messages. conclusion Although features and elements are provided above in specific combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with other features and elements. The present disclosure should not be limited with respect to the specific embodiments described in this application, which are intended as examples of various aspects. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from the spirit and scope thereof. No element, act, or instruction used in the description of this application should be construed as critical or essential to the invention unless expressly provided as such. In addition to those enumerated herein, functionally equivalent methods and apparatuses within the scope of the present disclosure will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to be encompassed within the scope of the appended claims. The present disclosure should be limited only by the claims of the appended claims, along with the full scope of equivalents to which such claims are entitled. It should be understood that the present disclosure is not limited to any particular method or system.

[0219] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the terms "station" and its abbreviation "STA", "user equipment" and its abbreviation "UE" when referred to herein can mean (i) a wireless transmit and / or receive unit (WTRU), as described below, (ii) any of a number of embodiments of a WTRU, as described below, (iii) a wireless-enabled and / or wired-enabled (e.g., connectable) device configured to use, among other things, some or all of the structure and functionality of a WTRU, as described below, (iv) a wireless-enabled and / or wired-enabled device configured to use less than all of the structure and functionality of a WTRU, as described below, or (v) the like. Details of an exemplary WTRU, which can be representative of any UE enumerated herein, have been provided, for example, with respect to Figures 1A-1D.

[0220] In addition, the methods described herein may be implemented in a computer program, software, or firmware contained in a computer-readable medium for execution by a computer or processor. Examples of non-transitory computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor associated with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

[0221] Modifications of the above-described methods, devices, and systems are possible without departing from the scope of the present invention. In view of the wide variety of possible embodiments that may be applied, it should be noted that the above-described embodiments are merely exemplary and are not limited by the scope of the following claims. For example, the embodiments included herein include handheld devices that include or are used in conjunction with a suitable voltage source, such as a battery or the like, that provides a suitable power supply voltage.

[0222] Furthermore, in the above-described embodiments, processing platforms, computing systems, controllers, and other devices including processors are described. These devices may include at least one central processing unit ("CPU") and memory. In accordance with the practices of those skilled in the art of computer programming, references to acts and symbolic representations of operations or instructions may be performed by various CPUs and memories. Such acts and operations or instructions may be said to be "executed," "computer-executed," or "CPU-executed."

[0223] Those skilled in the art will appreciate that the acts and symbolically represented operations or instructions include the manipulation of electrical signals by a CPU. The electrical system represents data bits, which can cause the resulting transformation or reduction of electrical signals and the retention of the data bits in memory locations within a memory system, thereby reconfiguring or otherwise altering the operation of the CPU and other processing of the signals. The memory locations in which the data bits are maintained are physical locations that have specific electrical, magnetic, optical, or organic properties that correspond to or represent the data bits. It should be understood that representative embodiments are not limited to the platforms or CPUs mentioned above, and that other platforms and CPUs can support the methods provided.

[0224] The data bits may also be maintained on a computer readable medium, including magnetic disks, optical disks, and any other volatile (e.g., random access memory ("RAM")) or non-volatile (e.g., read only memory ("ROM")) mass storage system readable by a CPU. The computer readable medium may include cooperative or interconnected computer readable media, which may reside exclusively on a processing system or distributed among multiple interconnected processing systems, which may be local or remote to a processing system. It is understood that representative embodiments are not limited to the memories mentioned above, and that other platforms and memories may support the methods described. It is understood that representative embodiments are not limited to the platforms or CPUs mentioned above, and that other platforms and CPUs may support the methods provided.

[0225] In an illustrative embodiment, any of the operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium. The computer-readable instructions may be executed by a processor of a mobile unit, a network element, and / or any other computing device.

[0226] There are few remaining differences between hardware and software implementations of aspects of the system. Whether to use hardware or software is generally (but not always, as in some circumstances the choice between hardware and software may be important) a design choice that represents a cost vs. efficiency tradeoff. There may be various means (e.g., hardware, software, and / or firmware) by which the processes and / or systems and / or other techniques described herein may be affected, and the preferred means may change with the circumstances in which the processes and / or systems and / or other techniques are deployed. For example, if the implementer determines that speed and accuracy are paramount, the implementer may select a primarily hardware and / or firmware implementation. If flexibility is paramount, the implementer may select a primarily software implementation. Alternatively, the implementer may select some combination of hardware, software, and / or firmware.

[0227] The above detailed description has described various embodiments of devices and / or processes through the use of block diagrams, flow charts, and / or examples. To the extent that such block diagrams, flow charts, and / or examples include one or more functions and / or operations, it will be understood by those skilled in the art that each function and / or operation within such block diagrams, flow charts, or examples can be implemented individually and / or collectively by a wide range of hardware, software, firmware, or substantially any combination thereof. In certain representative embodiments, some portions of the invention described herein can be implemented via application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), and / or other integrated configurations. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein may equivalently be implemented, in whole or in part, in an integrated circuit, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as substantially any combination thereof, and that designing circuitry and / or writing code for software and / or firmware is well within the skill of one of ordinary skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the inventive mechanisms described herein may be distributed in a variety of forms as a program product, and that the illustrative embodiments of the invention described herein apply regardless of the particular type of signal-bearing medium actually used to effect the distribution.Examples of signal bearing media include, but are not limited to, the following: recordable type media such as floppy disks, hard disk drives, CDs, DVDs, digital tape, computer memory, and transmission type media such as digital and / or analog communications media (e.g., fiber optic cables, wave guides, wired communications links, wireless communications links, etc.).

[0228] Those skilled in the art will understand that it is common in the art to describe devices and / or processes as described herein and then use technical techniques to integrate the described devices and / or processes into a data processing system. That is, at least some of the devices and / or processes described herein can be integrated into a data processing system through a reasonable amount of experimentation. Those skilled in the art will understand that a typical data processing system may generally include one or more of the following: a system unit housing, a video display device, memory such as volatile or non-volatile memory, computing entities such as microprocessors and digital signal processors, operating systems, drivers, graphical user interfaces, and application programs, one or more interaction devices such as a touchpad or screen, and / or a control system including feedback loops and control motors (e.g., feedback for sensing position and / or velocity, control motors for moving and / or adjusting components and / or quantities, etc.). A typical data processing system may be implemented utilizing any suitable commercially available components, such as those typically found in data computing / communication and / or network computing / communication systems.

[0229] A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, mobility management entity (MME) or evolved packet core (EPC), or any host computer. The WTRU may be used in conjunction with hardware and / or software implemented modules, including software defined radios (SDRs), and other components, such as cameras, video camera modules, videophones, speakerphones, vibration devices, speakers, microphones, television transceivers, hands-free headsets, keyboards, Bluetooth modules, frequency modulation (FM) radio units, near field communication (NFC) modules, liquid crystal display (LCD) display units, organic light emitting diode (OLED) display units, digital music players, media players, video game player modules, Internet browsers, and / or wireless local area network (WLAN) or ultra-wideband (UWB) modules.

[0230] The invention described herein sometimes illustrates different components that are contained within or connected to other different components. It should be understood that such depicted architectures are merely examples, and that in fact many other architectures that achieve the same functionality can be implemented. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality can be achieved. Thus, any two components herein that are combined to achieve a particular functionality can be viewed as being "associated" with one another such that the desired functionality is achieved, regardless of the architecture or intervening components. Similarly, any two components so associated can also be considered to be "operably connected" or "operably coupled" with one another to achieve the desired functionality, and any two components capable of being so associated can also be considered to be "operably coupled" with one another to achieve the desired functionality. Particular examples of operably coupleable include, but are not limited to, physically pairable and / or physically interacting components, and / or wirelessly interactable and / or wirelessly interacting components, and / or logically interacting and / or logically interacting components.

[0231] With respect to the use of substantially any plural and / or singular term herein, those skilled in the art can convert from the plural to the singular and / or from the singular to the plural as appropriate to the situation or application. For clarity, various singular / plural permutations may be expressly described herein.

[0232] It will be understood by those of ordinary skill in the art that, in general, the terms used herein, and particularly in the appended claims (e.g., the body of the appended claims), are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "including, but not limited to," etc.). It will be further understood by those of ordinary skill in the art that, if a specific number of claim recitations are introduced, such intention will be explicitly stated in the claim, and in the absence of such statement, no such intention exists. For example, where only one item is intended, the term "single," or similar language, may be used. As an aid to understanding, the following appended claims and / or description herein may include the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed as implying that the introduction of a claim recitation with the indefinite article "a" or "an" limits any particular claim that includes such an introduced claim recitation to embodiments that include only one such recitation, even when the same claim includes the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should be construed to mean "at least one" or "one or more"). The same applies to the use of definite articles used to introduce claim recitations. In addition, those skilled in the art will recognize that even if a specific number of claim recitations introduced is explicitly recited, such recitation should be construed to mean at least the recited number (e.g., an unqualified recitation of "two recitations" without other modifiers means at least two recitations, or more than two recitations).Furthermore, when conventional language similar to "at least one of A, B, and C, etc." is used, such syntax is generally intended in the sense that one of ordinary skill in the art would understand the conventional language (e.g., "a system having at least one of A, B, and C" includes, but is not limited to, systems having only A, only B, only C, A and B together, A and C together, B and C together, and / or A, B, C together, etc.). When conventional language similar to "at least one of A, B, or C, etc." is used, such syntax is generally intended in the sense that one of ordinary skill in the art would understand the conventional language (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, systems having only A, only B, only C, A and B together, A and C together, B and C together, and / or A, B, C together, etc.). It will be further understood by those skilled in the art that substantially any disjunctive word and / or phrase, whether in the description, claims, or drawings, presenting two or more alternative terms, should be understood to contemplate the possibility of including one of the terms, either of the terms, or both of the terms. For example, the phrase "A or B" is understood to include the possibility of "A", or "B", or "A and B". Furthermore, as used herein, the term "any of" followed by a list of multiple items and / or multiple categories of items is intended to include "any of", "any combination of", "any more of", and / or "any combination of more of" the items and / or categories of items, individually or in conjunction with other items and / or categories of items. Furthermore, as used herein, the term "set" or "group" is intended to include any number of items, including zero. Additionally, as used herein, the term "number" is intended to include any number, including zero.

[0233] In addition, when features or aspects of the disclosure are described in terms of a Markush group, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0234] As will be understood by those skilled in the art, for any and all purposes, such as with respect to providing a written description, all ranges disclosed herein encompass any and all possible subranges and combinations of subranges thereof. Any described range can be readily recognized as fully describing and allowing for the same range broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range described herein can be easily broken down into a lower third, a middle third, and an upper third, etc. As will also be understood by those skilled in the art, all words such as "up to," "at least," "greater than," and "less than" refer to a range that includes the number described and can be subsequently divided into subranges as described above. Finally, as will be understood by those skilled in the art, a range includes each individual member. Thus, for example, a group having 1 to 3 cells refers to a group having 1, 2, or 3 cells. Similarly, a group having 1 to 5 cells refers to a group having 1, 2, 3, 4, or 5 cells, and so on.

[0235] Moreover, the claims should not be read as limited to the order or elements provided unless stated to that effect. In addition, the use of the term "means for" in any claim is intended to invoke 35 U.S.C. ... [Industrial Applicability]

[0236] The present invention can be used in communications. [Explanation of symbols]

[0237] 102a~102d WTRU 104 RAN 106 Core Network 108 PSTN 110 Internet 112 Other Networks

Claims

1. 1. A method implemented in a wireless transmit / receive unit (WTRU), comprising: receiving one or more physical random access channel configurations, each of which indicates one of a preamble format and a physical random access channel opportunity period; selecting a physical random access channel configuration from among the physical random access channel configurations based on an ability of the WTRU to estimate a timing advance; transmitting a preamble using the selected physical random access channel configuration; A method for providing the above.

2. indicating to a network the capability of estimating a timing advance of the WTRU. The method of claim 1 comprising:

3. estimating a value of the timing advance; indicating the value of the estimated timing advance to a network; The method of claim 1 comprising:

4. adjusting the value of the timing advance based on one of satellite ephemeris, network-sourced control and data timing, and Global Navigation Satellite System (QNSS) information. The method of claim 3 comprising:

5. 4. The method of claim 3, wherein the step of selecting a physical random access channel configuration includes selecting one of a number of physical uplink shared channels and a number of preamble transmissions based on the value of the estimated timing advance.

6. The method of claim 1 , wherein the preamble format includes any one of a preamble sequence length, a number of repetitions, a cyclic prefix, and a guard period.

7. The method of claim 1 , wherein the physical random access channel opportunity period indicates a time between two consecutive physical random access channel opportunities.

8. 2. The method of claim 1, wherein selecting the physical random access channel configuration based on the WTRU having the ability to accurately estimate a timing advance includes selecting a physical random access channel configuration associated with a preamble and one or more physical uplink shared channel (PUSCH) transmissions.

9. 2. The method of claim 1, wherein selecting the physical random access channel configuration based on the WTRU's inability to accurately estimate a timing advance includes selecting a physical random access channel configuration associated with a plurality of preambles and one or more physical uplink shared channel (PUSCH) transmissions.

10. 1. A wireless transmit / receive unit (WTRU), comprising: A transmitter, a receiver, a processor and a memory, receiving one or more physical random access channel configurations, each of which indicates one of a preamble format and a physical random access channel opportunity period; selecting a physical random access channel configuration from among the physical random access channel configurations based on an ability of the WTRU to estimate a timing advance; Transmitting a preamble using the selected physical random access channel configuration. A circuit constructed as follows: A WTRU equipped with

11. The WTRU of claim 10 configured to indicate to a network the capability of estimating a timing advance of the WTRU.

12. Estimating a value of the timing advance; The WTRU of claim 10 , configured to indicate the value of the estimated timing advance to a network.

13. 13. The WTRU of claim 12, configured to adjust the value of the timing advance based on one of satellite ephemeris, network-sent control and data timing, and Global Navigation Satellite System (QNSS) information.

14. selecting the physical random access channel configuration, The WTRU of claim 12 , configured to select one of a number of physical uplink shared channels and a number of preamble transmissions based on the value of the estimated timing advance.

15. The WTRU of claim 10 , wherein the preamble format includes any one of a preamble sequence length, a number of repetitions, a cyclic prefix, and a guard period.

16. The WTRU of claim 10 , wherein the physical random access channel opportunity period indicates a time between two consecutive physical random access channel opportunities.

17. 11. The WTRU of claim 10, configured to select a physical random access channel configuration associated with one preamble and one or more physical uplink shared channel (PUSCH) transmissions based on the WTRU having the ability to accurately estimate a timing advance.

18. 11. The WTRU of claim 10, configured to select a physical random access channel configuration associated with multiple preambles and one or more physical uplink shared channel (PUSCH) transmissions based on the WTRU's inability to accurately estimate a timing advance.

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