Some implementations describe a method including: receiving, by multiple receivers of multiple gateways of a ground receiver system, from multiple transmitters of a satellite over a downlink of a LoS MIMO feeder link, multiple RF signals; obtaining, at the ground receiver system, from the RF signals, preamble signals and pilot signals including first sequences of pilot symbols associated with second sequences of pilot symbols transmitted by the transmitters; estimating, based on the first sequences of pilot symbols and second sequences of pilot symbols, first channel state information (CSI) of the pilot signals; estimating, using the first CSI, frequency offsets and phase offsets of links between the receivers and the transmitters; adjusting, based at least on the frequency offsets and the phase offsets, the preamble signals to obtain adjusted preamble signals; and estimating, at the ground receiver system, using the adjusted preamble signals, second CSI of the downlink.

A satellite communication system with software defined network orchestration. Implementations include a route management function (RMF) that receives link status from the satellites and determines simple routing tables which are uploaded to the satellites. The routing tables allow the satellites to route data based on a satellite ID placed in a data header to reduce the memory and computing load on satellite resources. Further, implementations include secure user terminal (UT) to UT IP routing in the constellation for direct UT to UT communication. The satellite communication system may combine the benefits of Medium Earth Orbit (MEO) and Low Earth Orbit (LEO) satellite systems into an MEO-LEO satellite system.

The orbital states (position and/or time) for a constellation of space vehicles is determined as follows. The space vehicles measure PNT data, including range data determined based on FSO links between the space vehicles. The PNT data is transmitted from the space vehicles to two or more PNT controllers, which are a subset of the space vehicles that calculate the orbital state data for the constellation. This is a semi-distributed calculation. There is not a single controller that performs the calculations for all of the space vehicles in the constellation, and it is also not the case that each space vehicle performs its own calculations. Rather, each PNT controller services a sub-constellation of the space vehicles and determines the orbital state data for the space vehicles in the sub-constellation. The calculated orbital state data is transmitted from the PNT controllers to the space vehicles in the corresponding sub-constellations.

Methods, systems, and devices for wireless communications are described. A network node and a user equipment (UE) may establish a connection between the UE and the network node of a non-terrestrial network. The UE may receive, from the network node and based on a type of orbit around Earth of the network node, a first value or the first value and a second value associated with a position or a velocity of the network node relative to a terrestrial-based reference. The UE and the network node may communicate based on the position or the velocity of the network node, or both. In some cases, the position or the velocity of the network node is based on an altitude of the network node, the first value, the second value, and a third value.

The present teachings include a method and computing apparatus for triggering synchronization of a satellite modem to a carrier frequency of a beam of a satellite, retrieving ephemeris information for the satellite and beam configuration information for the beam, calculating a velocity of the satellite per the ephemeris information, and adjusting the carrier frequency of the satellite modem when communicating via the beam to compensate for a doppler offset induced in the carrier frequency by the velocity. In the method, the satellite has a satellite type selected from a Geosynchronous Earth Orbit (GEO), Medium Earth Orbit (MEO) or Low Earth Orbit (LEO) type of satellite, and the satellite type is different than a satellite type of an immediately preceding synchronization.

One variation of a method includes: training a first model to predict failures within the first population of satellites within a first time window based on a first set of historical timeseries telemetry data and a first set of historical timeseries failure data; and training a second model to predict failures within the first population of satellites within a second time window, shorter than the first time window, based on the first set of historical timeseries telemetry data and the first set of historical timeseries failure data. The method further includes: predicting a first probability of failure of the first satellite within the first time window based on the first model and the first set of timeseries telemetry data; and predicting a second probability of failure of the first satellite within the second time window based on the second model and the first set of timeseries telemetry data.

A method and apparatus for configuring a communication network based on a distance metric. Information indicative of current status of communication network nodes, links between the nodes, or a combination thereof is obtained and processed to determine a network configuration. The network configuration is implementable in the communication network by adjusting one or more nodes or links. The processing includes evaluating network configurations based on a distance metric, which is indicative of lengths of shortest paths which interconnect nodes of the network. Instructions directing underlying resources to implement the network configuration can be provided. An apparatus can be a supervisory device including a network interface and a computer processor.

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.

A method for generating a wireless signal fingerprint database includes: obtaining an initial atmospheric pressure value, in which the initial atmospheric pressure value is an atmospheric pressure value collected when a terminal enters indoors; obtaining periodically a current wireless signal fingerprint and a current atmospheric pressure value collected by the terminal; and determining a floor corresponding to the current wireless signal fingerprint based on the initial atmospheric pressure value and the current atmospheric pressure value, to obtain the wireless signal fingerprint database.

An indication method and an indication device are provided. The method includes obtaining satellite parameters of a current satellite cell and one or more neighbor satellite cells, wherein the current satellite cell is a satellite cell where a terminal is located, the one or more neighbor satellite cells are satellite cells neighboring the current satellite cell; determining a basic list and a detailed list according to the satellite parameters of the current satellite cell and the neighbor satellite cells, wherein the basic list includes basic information of the neighbor satellites, and the detailed list includes detailed information of the neighbor satellites; sending the basic list and/or the detailed list to the terminal.