Systems and methods for supporting more flexible coverage areas and spatial capacity assignments using satellite communications systems are disclosed. A hub-spoke, bent-pipe satellite communications system includes: terminals; gateways; a controller for specifying data for controlling satellite operations in accordance with a frame definition including timeslots for a frame and defining an allocation of capacity between forward and return traffic. The satellite communications system may employ a satellite with a feed array assembly and may use on-board beamforming or ground-based beamforming. Beam hopping within timeslots of the frame may be used to provide coverage to different cells in different time periods. The flexible coverage areas may be provided using changes in satellite position, antenna patterns, or beam resource allocations.

A control method and a control device in a heterogeneous three-dimensional hierarchical network, and a communication system are provided. The control method includes: obtaining a coverage mode of a terminal; when the coverage mode is single-layered sub-network coverage, setting a non-ground mobile communication sub-network or a ground mobile communication sub-network corresponding to the single-layered sub-network coverage to be in a standalone operating mode or an intra-layer carrier aggregation mode; and when the coverage mode is multi-layered sub-network coverage, setting the non-ground mobile communication sub-network corresponding to the multi-layered sub-network coverage, or the ground mobile communication sub-network and the non-ground mobile communication sub-network corresponding to the multi-layered sub-network coverage, to be in a cross-layer carrier aggregation mode. The ground mobile communication sub-network and the non-ground mobile communication sub-network use a same or unified radio access technology.

Aspects of the disclosure are directed to a random access method that can include determining first information that indicates a random access configuration of a satellite cell. The random access method can further include sending the first information.

Systems and methods for controlling satellites are provided. In one example embodiment, a computing system can obtain a request for image data. The request can be associated with a priority for acquiring the image data. The computing system can determine an availability of a plurality of satellites to acquire the image data based at least in part on the request. The computing system can select from among a plurality of communication pathways to transmit an image acquisition command to a satellite based at least in part on the request priority. The plurality of communication pathways can include a communication pathway via which the image acquisition command is indirectly communicated to the satellite via a geostationary satellite. The computing system can send the image acquisition command to the selected satellite via the selected communication pathway.

A method and an apparatus for performing a random access procedure in a wireless communication system are disclosed. A method of performing a random access procedure according to an embodiment of the present disclosure may include receiving, from a base station, configuration information for providing information needed for the terminal to access the wireless communication system via a non-terrestrial network (NTN) including a satellite, wherein the configuration information includes first information for adjusting an orbit of the satellite and second information on common timing advance (TA); and determining a terminal-specific TA value for the terminal based on a location of the terminal and the configuration information; and transmitting, to the base station, a first message for the random access procedure at a timing determined based on the terminal-specific TA value and a common TA value derived from the second information.

A method and an apparatus for performing a random access procedure in a wireless communication system are disclosed. A method of performing a random access procedure according to an embodiment of the present disclosure may include receiving, from a base station, configuration information for providing information needed for the terminal to access the wireless communication system via a non-terrestrial network (NTN) including a satellite, wherein the configuration information includes first information for adjusting an orbit of the satellite and second information on common timing advance (TA); and determining a terminal-specific TA value for the terminal based on a location of the terminal and the configuration information; and transmitting, to the base station, a first message for the random access procedure at a timing determined based on the terminal-specific TA value and a common TA value derived from the second information.

Various solutions for satellite access network (SAN) or non-terrestrial network (NTN) measurement with respect to user equipment and network apparatus in mobile communications are described. An apparatus may determine a first number of synchronization signal blocks (SSBs) or SSB-based radio resource management (RRM) measurement timing configurations (SMTCs) overlapped in a time domain. The apparatus may determine a second number of satellites to be measured in each of the SMTCs. The apparatus may calculate a scaling factor according to the first number and the second number. The apparatus may determine a measurement period by applying the scaling factor. The apparatus may perform measurements on the satellites within the measurement period.

Various solutions for satellite access network (SAN) or non-terrestrial network (NTN) measurement and data scheduling with respect to user equipment and network apparatus in mobile communications are described. An apparatus may determine whether to perform a measurement outside a measurement gap for a neighboring cell. The apparatus may apply a scheduling restriction within a time period in an event that the measurement is determined. The apparatus may transmit uplink symbols or receiving downlink symbols outside the time period with the scheduling restriction.

Various arrangements are presented for using an estimated timing advance for user equipment communications. A location of an instance of user equipment may be determined. An estimated distance between the user equipment and a communication satellite may be determined using the determined location of the user equipment and an estimated satellite location. An estimated timing offset using the calculated estimated distance may be determined. An uplink data frame may be transmitted by the user equipment to the satellite such that a timing of transmission of the uplink data frame is based on the calculated estimated timing offset.

Embodiments of the present invention comprise a signal processing method and apparatus for use in a satellite payload in which an input RF signal received at a receiver antenna is modulated by using a single optical carrier at the input of an optical modulator. The optical domain signal is processed and is subsequently combined with a single unmodulated optical LO tone to provide an output RF signal for radiation by a transmitter antenna or for further digital processing by an on-board processor. This results in a clean generation of the frequency-converted RF signal at the output of the opto-electrical conversion stage.