A method for uplink (UL) synchronization, a communication apparatus, and a storage medium are disclosed in embodiments of the disclosure. The method for UL synchronization includes: determining, by a terminal device, one or more transmission gaps in a UL shared channel resource, where the UL shared channel resource is a resource occupied by a scheduled UL shared channel, and the one or more transmission gaps are each M continuous time units subsequent to every N time units in the UL shared channel resource, and performing UL synchronization by using the one or more transmission gaps during transmission of the UL shared channel.

This application provides an uplink timing method. A half-duplex terminal device determines, based on a maximum timing advance of an area in which the terminal device is located and a set of time units used by the terminal device to receive a system message, a set of time units unavailable for uplink transmission, and in a process of calculating a time unit for sending an uplink signal, skips, based on a scheduling offset of the uplink signal, a time unit in the set of time units unavailable for uplink transmission, to avoid a problem that the half-duplex device needs to simultaneously perform receiving and sending in a large transmission latency scenario.

Certain aspects of the present disclosure provide techniques for enhancing ephemeris for non-terrestrial networks. For example, UEs of different orbit propagation capabilities (e.g., computing orbit propagation models of different accuracy levels) may receive additional ephemeris parameters. In one aspect, a network entity may determine at least one additional set of ephemeris parameters that includes different ephemeris parameters than one or more basic sets of ephemeris parameters associated with a satellite that provides a coverage for the network entity. The network entity may transmit broadcast signaling indicating the at least one additional set of ephemeris parameters. The UE may receive and use the at least one additional set of ephemeris parameters in an orbit propagation model to compute a state of motion of the satellite.

Systems and methods for differentiated application of an Adaptive Coding and Modulation (ACM) to enhance link performance in satellite communication systems are disclosed. A system may include a processor and a memory storing instructions, which when executed by the processor, cause the processor to dynamically compute bandwidth capacity of a terminal from a plurality of terminals. Based on the computed bandwidth capacity of the terminal, the processor may automatically determine a ModCod to be applied for transmission to or from the terminal to optimize bit error rate (BER) performance. The to processor may determine the ModCod using an ACM technique. For the plurality of terminals, the processor may dynamically determine aggregate bandwidth availability and congestion within the ACM technique to optimize sharing of available bandwidth.

This application provides a satellite communication method and apparatus. A terminal obtains a level-1 broadcast signal from a satellite, where a beam status corresponding to the level-1 broadcast signal is an energy saving state, and the level-1 broadcast signal includes synchronization information. The terminal obtains a level-2 broadcast signal from the satellite, where a beam status corresponding to the level-2 broadcast signal is a broadband communication state. The terminal communicates with the satellite based on the level-2 broadcast signal.

A communication system, includes a satellite receiver in operable communication with a central server, a cellular node configured to operate within a proximity of the satellite receiver, and at least one mobile communication device configured to communicate (i) with the cellular node, (ii) within the proximity of the satellite receiver, and (iii) using a transmission signal capable of causing interference to the satellite receiver. The satellite receiver is configured to detect a repeating portion of the transmission signal and determine a potential for interference from the at least one mobile communication device based on the detected repeating portion.

Appropriate timing control is realized in accordance with propagation delay between a terminal and a base station. This terminal includes: a control unit that controls a transmission timing on the basis of first information relating to control of transmission timing of signals in a transmission increment of the signals, and second information relating to control of transmission timing in a finer increment than in the transmission increment; and a wireless transmission unit that performs signal transmission on the basis of control of the transmission timing by the control unit.

Systems and methods are disclosed for random access in a wireless communication system such as, e.g., a wireless communication system having a non-terrestrial (e.g., satellite-based) radio access network. Embodiments of a method performed by a wireless device and corresponding embodiments of a wireless device are disclosed. In some embodiments, a method performed by a wireless device for random access comprises performing an open-loop timing advance estimation procedure to thereby determine an open-loop timing advance estimate for an uplink between the wireless device and a base station. The method further comprises transmitting a random access preamble using the open-loop timing advance estimate. In this manner, random access can be performed even in the presence of a long propagation delay such as that present in a satellite-based radio access network. Embodiments of a method performed by a base station and corresponding embodiments of a base station are also disclosed.

A disclosure of the present specification provides a terminal which uses a frequency band of a mobile satellite service for LTE/LTE-A. The terminal comprises: a first duplexer for separating a transmitted signal and a received signal in band 1 defined in long term evolution (LTE)/LTE-Advanced; a second duplexer for separating a transmitted signal and a received signal in new band 65 which was a mobile satellite service (MSS) band and now is allocated for the terrestrial service; and a selection switch for selecting one of the first duplexer and the second duplexer. Herein, when only band 1 is configured and used, only the first duplexer may be operated by the selection switch. In contrast, when new band 65 is configured and used, wherein the configured band does not overlap the range of band 1, and when new band 65 is configured and used, wherein the configured band overlaps the range of band 1 for carrier aggregation, only the second duplexer may be operated by the selection switch

Methods and systems for repurposing of a global navigation satellite system receiver for receiving low-earth orbit (LEO) communication satellite timing signals may comprise receiving a medium Earth orbit (MEO) satellite signal and/or a LEO signal in a receiver of the communication device. The MEO or LEO signal may be down-converted, and a position of the communication device may be calculated utilizing the down-converted signal. The signal may be down-converted utilizing a local oscillator signal generated by a phase locked loop (PLL), which may be delta-sigma modulated via a fractional-N divider. A clock signal may be communicated to the PLL utilizing a temperature-compensated crystal oscillator. The signal may be down-converted to an intermediate frequency or down-converted directly to baseband frequencies. The signal may be processed utilizing surface acoustic wave (SAW) filters. In-phase and quadrature signals may be processed in the RF path utilizing a two-stage polyphase filter.