Methods for a New Radio (NR)-based, Low Earth Orbit (LEO) Non-Terrestrial Networks (NTN) are proposed to improve cell selection and reselection by using satellite assistance information. Different from traditional 5G New Radio systems, the LEO NTN can provide the next cell information along the satellite trajectory using System Information Broadcast (SIB). The assistance information can include satellite's long term ephemeris in the format of Position Velocity (PV) information or details of satellite's other orbital parameters. During TN-NTN join coverage, as TN cells are expected to have a better coverage then NTN cells, the network can assign higher priority to the TN cells over NTN cells. Similarly, for a mobility involving earth-fixed and earth-moving beams (cells), earth-fixed cells can be prioritized over earth-moving beams for cell reselection.

There is provided mechanisms for random access handling of a UE. A method is performed by a network node. The method comprises receiving, from the UE during a first RAO, a first RA preamble, whilst refraining from responding to the first RA preamble. The method comprises transmitting, towards the UE and without the network node first having received any retransmitted RA preamble from the UE, one RAR for each of N possible RA preambles, where each RAR comprises a TA command corresponding to a TA value estimated for the first RA preamble. The method comprises receiving, from the UE during a further RAO, a retransmitted RA preamble. The method comprises determining whether the TA value for the retransmitted RA preamble matches the TA value for the first RA preamble or not.

Systems, methods, apparatuses, and computer program products for dynamic cell-specific delay for timing scaling in a non-terrestrial network (NTN). For example, certain embodiments may utilize a cell-common delay composed of FL and part of SL (until a cell-specific reference surface). A network node (e.g., a gNB) may calculate the cell-common delay as a function of time (T_c(t)) and may provide this function to the UEs (the satellite path may beis deterministic). The function of time may be a combination of two functions representing the FL and SL. The function can may be broadcasted in a system information block (SIB) or transmitted directly to the UE through radio resource control (RRC) signaling when it becomes active, is handed over, and/or regularly updated.

Methods, apparatuses, computer-readable mediums for storing software, and systems for dynamic geographical spectrum sharing (DGSS) by Earth exploration satellite services (EESS) are described herein. Using DGSS mechanisms described herein, electromagnetic spectrum may be shared by sensors onboard Earth exploration satellites and wireless networks, such as 5G networks. The DGSS mechanisms may include mechanisms for determining an instantaneous field of view (IFOV) and mechanisms for modifying transmission characteristics while network antennas and power radiated by such antennas are within a window encompassing the IFOV. For example, when the IFOV of a satellite sensor for measuring atmospheric water includes a 5G antenna, the power of the 5G antenna may be reduced, the 5G antenna may be prevented from utilizing a segment of the electromagnetic spectrum, etc. The DGSS mechanisms may also determine actual out of band emissions for a specific pixel associated with the IFOV and improve pixel location determinations.

This application provides a buffer determining method and apparatus, to resolve a problem of how a terminal device on a sidelink calculates a buffer size. The method includes: A terminal device determines a sidelink data rate, and determines a buffer size based on the sidelink data rate. In this embodiment of this application, the terminal device may determine the buffer size based on the sidelink data rate, to calculate a buffer size of terminal device in sidelink communication.

The present disclosure relates to a user equipment (UE) that comprises a receiver of the UE receives, from a source base station of a source radio cell, a common timing advance value for a target radio cell. The UE is connected to the source radio cell and is involved in a handover procedure to hand over the UE from the source radio cell to the target radio cell. Further, the common timing advance value is received from the source base station in a first message of the handover procedure, which also comprises a timing indication for transmitting a second message from the UE to the target base station. Then, a processor of the UE determines a first uplink timing of uplink transmissions to the target base station with respect to downlink transmissions from the target base station, based on the received common timing advance value and the timing indication. A transmitter of the UE transmits a second message of the handover procedure to the target base station based on the determined uplink timing. The processor determines a UE-specific timing advance value, specific to the UE and the target radio cell, to be used by the UE for performing uplink transmissions in the target radio cell.

The invention relates to a solution for determining an allowable round trip time for a communication between a base station and a terminal device served by the base station in an asynchronous communication system, At least some aspects of the solution relate to a method performed by a controller, the method comprises: determining round trip times of terminal devices served by the base station; selecting a maximum round trip time among the determined round trip times of the terminal devices served by the base station as the allowable round trip time; and delivering the selected allowable round trip time to the base station. The solution also relates to applying the determined round trip time by a base station and a terminal device as well as to a system comprising the mentioned entities and to computer program products.

A satellite visibility assignment device (1) includes a visibility unit setter (21), a visibility unit selector (22), and an optimization calculator (23). The visibility unit setter (21) sets visibility units each including a combination of a satellite and a station to communicate with the satellite, a lower limit of a visibility start time, and an upper limit of a visibility end time. The optimization calculator (23) determines whether the visibility start time and the visibility end time are settable for each of the one or more combinations of the visibility units within a range satisfying a set constraint and calculates the visibility start time and the visibility end time through an optimization calculation. The visibility unit selector (22) selects, from the combinations of the visibility units, a combination of the visibility units to be used based on determination of the optimization calculator (23).

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive information that indicates whether to perform a first random access channel (RACH) procedure for a non-terrestrial network or a second RACH procedure for a terrestrial network, wherein the first RACH procedure is configured to support a larger number of UEs contemporaneously performing a RACH procedure than the second RACH procedure. Responsive to the information indicating that the UE is to perform the first RACH procedure, the UE may perform the first RACH procedure. Numerous other aspects are provided.

A user terminal (UT) for a mobile satellite communications system, and an associated method for managing tracking areas for such a UT is provided. When initiating establishment of a radio connection, the UT transmits a connection request message to a satellite gateway (SGW) of the mobile satellite communications system, where the connection request message includes position information identifying a current location of the UT. The UT processes a connection setup message received in response to the connection request message, where the connection setup message includes a first tracking area identifier (TAID) that identifies a one of a plurality of tracking areas that is associated with the current location of the UT. The UT transmits a connection complete message to the SGW, together with an attach request message for a core network of the mobile satellite communications system, which includes the first TAID.