Abstract: Various solutions for synchronization in non-terrestrial network (NTN) communications are proposed. An apparatus implemented in a user equipment (UE) obtains at least one of a downlink (DL) pre-compensated frequency value applied on a service link from a satellite of a non-terrestrial network (NTN) and a feeder link delay drift rate of a feeder link between a network node and the satellite. The apparatus further obtains a Doppler frequency shift value. Then, the apparatus performs a timing compensation through adjusting a sampling rate according to at least one of the DL pre-compensated frequency value, the feeder link delay drift rate, and the Doppler frequency shift value.

Abstract: Various solutions for slot aggregation design in non-terrestrial network (NTN) communications with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a demodulation reference signal (DMRS) time bundling configuration. The apparatus may determine a duration interval of the DMRS time bundling configuration. The apparatus may perform phase continuity cross slots of same aggregated slots transmitted in the NTN communications based on the duration interval.

Abstract: Various solutions for slot aggregation design in non-terrestrial network (NTN) communications with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a demodulation reference signal (DMRS) time bundling configuration. The apparatus may determine a duration interval of the DMRS time bundling configuration. The apparatus may perform channel estimation cross slots based on the duration interval.

Abstract: Various solutions for capability indication of repetition for Message 4 (Msg4) hybrid automatic repeat request (HARQ)-acknowledgement (ACK) or Msg4 HARQ-negative ACK (NACK) are described. An apparatus may receive a system information block (SIB) from a network node of a wireless network, wherein the SIB comprises one or more physical uplink control channel (PUCCH) repetition numbers for Msg4. The apparatus may report a capability indication of PUCCH repetition for Msg4 HARQ-ACK or Msg4 HARQ-NACK to the network node through a Message 1 (Msg1) or a Message 3 (Msg3). The apparatus may transmit with repetitions a PUCCH with HARQ-ACK information or HARQ-NACK information for Msg4 to the network node according to one of the one or more PUCCH repetition numbers for Msg4.

Abstract: Various solutions for random access channel (RACH) preamble design in non-terrestrial network (NTN) communications with respect to user equipment and network apparatus are described. An apparatus may initiate a RACH procedure. The apparatus may determine a fractional frequency offset pattern or a cover code across groups of preamble sequences. The apparatus may generate a RACH preamble signal according to at least one of the fractional frequency offset pattern and the cover code. The apparatus may transmit the RACH preamble signal to a network node.

Abstract: Various solutions for Message 4 (Msg4) transmission with respect to user equipment and network node in mobile communications are described. An apparatus may determine whether at least one repetition factor for Msg4 is configured in a system information block (SIB) from a network node. The apparatus may determine whether an indication for Msg4 repetition is configured in a downlink control information (DCI) from the network node. The apparatus may determine a number of repetitions for Msg4 based on at least one of the SIB and the DCI. The apparatus may receive one or more Msg4s from the network node according to the number of repetitions. The apparatus may transmit one or more Msg4 Hybrid Automatic Repeat Request (HARQ)-acknowledgements (ACKs) to the network node according to the number of repetitions.

Abstract: Various solutions for global navigation satellite system (GNSS) operations with respect to user equipment and network node in mobile communications are described. An apparatus may transmit a GNSS position fix time duration and a GNSS validity duration to a network node during an initial access. The apparatus may receive a configuration based on the GNSS position fix time duration and the GNSS validity duration from the network node in a connected mode. The apparatus may perform a GNSS measurement based on the configuration. The apparatus may transmit a new GNSS validity duration to the network node in the connected mode in an event that the apparatus completes the GNSS measurement.

Abstract: In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE determines multiple uplink measurement occasions for transmitting multiple reference signals to a satellite in a non-terrestrial network (NTN). The UE generates, based on Global Navigation Satellite System (GNSS) location data of the UE and ephemeris data of the satellite, multiple timing advance (TA) reports that are linked to the multiple uplink measurement occasions, respectively. The UE transmits the multiple TA reports to the satellite at multiple time points. The UE transmits the multiple uplink reference signals to the satellite on the uplink measurement occasions.

Abstract: Various solutions for timing and frequency compensation in non-terrestrial network (NTN) communications are proposed. An apparatus implemented in a user equipment (UE) obtains a carrier frequency of an NTN. The apparatus generates an up-conversion signal by upconverting a baseband signal according to the carrier frequency. Then, the apparatus further obtains a pre-compensation frequency value. The apparatus performs an uplink (UL) frequency pre-compensation through adjusting a phase of the up-conversion signal according to the pre-compensation frequency value.

Abstract: Various solutions for time and frequency in non-terrestrial network (NTN) communications are proposed. An apparatus implemented in a user equipment (UE) obtains a center frequency and a reference time of a non-terrestrial network. The apparatus further obtains a feeder link delay of a feeder link between a network node and a satellite, and a service link delay drift rate of a service link between the apparatus and the satellite. Then, the apparatus performs an uplink frequency pre-compensation through calculating an uplink transmit frequency according to the center frequency, the reference time, the feeder link delay, and the service link delay drift rate.

Abstract: Various solutions for synchronization and feeder link delay drift in non-terrestrial network (NTN) communications are described. An apparatus (e.g., a UE) receives from a network information of a common timing advance (TA), a common TA drift rate, and a common TA drift rate variation at a reference time. The apparatus determines a TA delay based on the information. The apparatus then performs NTN communications with the network with the TA delay accounted for.

Abstract: Various solutions for slot aggregation design in non-terrestrial network (NTN) communications with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a demodulation reference signal (DMRS) time bundling configuration. The apparatus may determine a duration interval of the DMRS time bundling configuration. The apparatus may perform channel estimation cross slots based on the duration interval.

Abstract: Solutions pertaining to spectrum sharing between a terrestrial network (TN) and a non-terrestrial network (NTN) with interference control are proposed. An apparatus implemented in a UE communicates with a non-terrestrial (NT) network node of the NTN by resource sharing with the TN. There is a requirement on either or both of a directive gain and a directive emission power with respect to a network node of the TN such that interference between TN downlink (DL) transmissions and NTN uplink (UL) transmissions is less than a threshold.

Abstract: In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. In certain configurations, the UE determines one or more types of global navigation satellite system (GNSS) related information and GNSS assistance information. The UE reports the one or more types of GNSS related information and the GNSS assistance information to a base station. The UE receives, from the base station, a scheduling indication for scheduling a timer or a gap to re-acquire a GNSS position fix. The UE acquires, in a radio resource control (RRC) connected state, the GNSS position fix in a time period determined according to the scheduling indication.

Abstract: In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. In certain configurations, the UE determines a global navigation satellite system (GNSS) validity duration or a remaining GNSS validity duration indicating a time duration for which a GNSS position fix is valid. The UE reports, to a base station, GNSS assistance information including the GNSS validity duration or the remaining GNSS validity duration. The UE attempts to acquire, at the UE and in a radio resource control (RRC) connected state, the GNSS position fix periodically or aperiodically.

Abstract: Various solutions for synchronization in non-terrestrial network (NTN) communications are proposed. An apparatus implemented in a user equipment (UE) obtains at least one of a downlink (DL) pre-compensated frequency value applied on a service link from a satellite of a non-terrestrial network (NTN) and a feeder link delay drift rate of a feeder link between a network node and the satellite. The apparatus further obtains a Doppler frequency shift value. Then, the apparatus performs a timing compensation through adjusting a sampling rate according to at least one of the DL pre-compensated frequency value, the feeder link delay drift rate, and the Doppler frequency shift value.

Abstract: Various solutions for slot aggregation design in non-terrestrial network (NTN) communications with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a demodulation reference signal (DMRS) time bundling configuration. The apparatus may determine a duration interval of the DMRS time bundling configuration. The apparatus may perform channel estimation cross slots based on the duration interval.

Abstract: Solutions pertaining to spectrum sharing in coordination between a non-terrestrial network (NTN) and a terrestrial network (TN) are proposed. An apparatus implemented in a UE measures a signal strength of each of one or more TN cells and one or more NTN cells. The apparatus reports a result of the measuring to a TN. The apparatus also receives an indication from the TN configuring and activating a bandwidth part (BWP) that separates transmission by a base station of the TN from NTN downlink (DL) transmissions.

Abstract: Solutions pertaining to configuration of spectrum sharing between a terrestrial network (TN) and a non-terrestrial network (NTN) are proposed. An apparatus implemented in a UE communicates with a non-terrestrial (NT) network node of the NTN by resource sharing with the TN. The resource sharing involves resource sharing with pairing of uplink (UL) and downlink (DL) transmissions of the NTN and the TN.

Abstract: Various examples and schemes pertaining to enabling or disabling hybrid automatic repeat request (HARQ) feedback for multi-transport block (multi-TB) in an Internet-of-Things (IoT) non-terrestrial network (NTN) are described. A user equipment (UE) receives a configuration (e.g., from a network). Then, the UE applies the configuration to disable or enable a HARQ feedback regarding multiple TBs.