Space Exploration Technologies Corp.

Martin S McCormick

Jeffrey C Strait

Chen Chen

Alazar Tamrat

Ronald Gottula

Stephan O Roche

Philip J Treigherman

Feipeng Wang

Torbjorn Larsson

Peter J Worters

Andrew G Whitlow

Matthew J Monson

A modem is configurable on a satellite, user terminal or gateway generates a radio frequency (RF) signal using an orthogonal frequency division multiplexing (OFDM) protocol including a radio frame including one or more bursts. A burst of the one or more bursts includes a first portion including burst detection data, a second portion including channel characteristic estimation data, a third portion including payload data, and fourth and fifth portions including pilot data. The first portion in a time domain is included in the burst prior to the second, third, fourth, and fifth portions. The first portion can include a pseudo-random noise sequence inserted in the time domain. The same physical modem can be configured to transmit signals on an uplink or downlink between a user terminal and a satellite or on the uplink or downlink between the satellite and the gateway.

Configurable orthogonal frequency division multiplexing (OFDM) signal and transmitter and receiver for satellite to gateway uplink and downlink communications

In an embodiment, a method includes determining a first beam pointing vector associated with an antenna assembly by searching for a satellite from a plurality of satellites. The method includes maintaining a communication link with the satellite by determining a plurality of beam pointing vectors that converge to a signal quality value. The method includes obtaining, from the satellite, satellite ephemeris information of the satellite and one or more of remaining satellites of the plurality of satellites. The method includes determining an estimated orientation of the antenna assembly based on one or more of the satellite ephemeris information and the plurality of beam pointing vector. The method includes determining a second beam pointing vector based on the estimated orientation, the satellite ephemeris information, and an approximate position information of the antenna assembly.

Determination of electronic beam steering angles

A wireless communications system includes a pre-distortion actuator configured to receive a carrier-modulated signal and convert the carrier-modulated signal into an output signal, the pre-distortion actuator comprising a behavioral model that models a transmit chain of the system including at least one amplifier and at least one antenna and predict an input-output relationship of the transmit chain of the system between an input to the transmit chain to an output of the transmit chain. The system includes a phased antenna array configured to transmit the output signal. The phased antenna array includes a plurality of antenna elements, each antenna element electrically coupled to a respective power amplifier. The pre-distortion actuator is configured to generate the output signal by applying a correction to the carrier-modulated input signal that cancels out nonlinearities The behavioral model is updated based on feedback from a receiver from a previous output signal transmitted to the receiver.

Digital pre-distortion compensation in a wireless communications system

In an embodiment, an apparatus includes an antenna assembly configured to transmit and receive beams in time-varying directions, and a beam steering controller configured to determine a first beam pointing vector by searching for a satellite from a plurality of satellites included in the communication system. The antenna assembly maintains a communication link with a satellite of the plurality of satellites by determining a plurality of beam pointing vectors that converge to increasing signal quality measurements, the satellite associated with the first beam pointing vector. The beam steering controller is configured to obtain, from the satellite, satellite ephemeris information of the satellite and one or more of remaining satellites of the plurality of satellites. The beam steering controller is configured to determine an orientation of the antenna assembly based on the satellite ephemeris information and the plurality of beam pointing vectors.

Determination of spatial orientation

Configurable orthogonal frequency division multiplexing (OFDM) signal and transmitter and receiver for same

Configurable orthogonal frequency division multiplexing (OFDM) signal and transmitter and receiver for satellite to user terminal downlink communications

Configurable orthogonal frequency division multiplexing (OFDM) signal and transmitter and receiver for user terminal to satellite uplink communications

Systems, methods, and non-transitory media are provided for synchronization of multi-user uplink transmissions. An example method can include receiving, by a user terminal, a downlink radio frame transmitted by a satellite; determining, by the user terminal, a downlink propagation delay associated with the downlink radio frame and an uplink propagation delay associated with an uplink radio frame from the user terminal to the satellite; based on the downlink propagation delay and the uplink propagation delay, determining, by the user terminal, an uplink transmission delay indicating an amount of time to delay a transmission of the uplink radio frame to the satellite so the uplink radio frame is received at the satellite at a same target time as one or more additional uplink radio frames from one or more additional user terminals; and transmitting, by the user terminal, the uplink radio frame at a time corresponding to the uplink transmission delay.

Synchronization of multi-user uplink transmissions

Systems, methods, and non-transitory media are provided for timing half-duplex transmissions in a wireless communication system. An example method can include receiving, by a user terminal (UT), a radio frame transmitted by a satellite to a group of UTs; identifying an offset delay defined in the radio frame for scheduling transmissions between the satellite and each UT in the group of UTs, the offset delay providing non-overlapping time intervals for receive, process, and transmit operations at each UT; determining, based on the offset delay and a time when the radio frame was received by the UT, a time for transmitting an uplink radio burst to the satellite, wherein the uplink radio burst transmitted at the time is estimated to arrive at the satellite within a same radio frame interval as uplink radio bursts from other UTs; and transmitting, to the satellite, the uplink radio burst at the time.

Timing half-duplex transmissions

In an embodiment, an apparatus includes an antenna assembly, a modem, and a beam steering controller. A beam steering controller is configured to determine a beam pointing direction of the antenna assembly to be able to one or both of switch a first communication link with a first satellite to a second communication link with a second satellite or establish and maintain the first communication link with the first satellite. At a start of a determination of the beam pointing direction, one or more of an orientation of the antenna assembly is unknown, positions of a plurality of satellites are unknown, or downlink frequencies of the plurality of satellites are unknown.

In an embodiment, a cross-polarization interference compensation module is included in a receiver of a wireless communication system. The module includes first and second input lines configured to receive respective first and second down-converted digital polarized signals based on receipt of a wireless transmission. The module further includes first and second output lines electrically coupled to at least one modem. The module further includes a first complex finite impulse response (FIR) filter configured to receive the second down-converted digital polarized signal and generate a correction factor that cancels cross-polarization components in the first down-converted digital polarized signal. The module further includes a first filter coefficient engine in communication with the first complex FIR filter and configured to adapt the first complex FIR filter over time based on the first and second down-converted digital polarized signals.

Cross-polarization interference compensation

A wireless communications system includes a pre-distortion actuator configured to receive a carrier-modulated signal and convert the carrier-modulated signal into an output signal. The system includes one or more antennas configured to receive the output signal and transmit the output signal, one or more power amplifiers electrically coupled between the pre-distortion actuator and the one or more antennas and a receiver configured to receive the output signal over-the-air and generate feedback based on the output signal. The pre-distortion actuator is configured to generate the output signal by applying a correction to the carrier-modulated signal that cancels out nonlinearities associated with the one or more antennas and/or the one or more power amplifiers. The pre-distortion actuator is configured based on the feedback.

Digital pre-distortion compensation using combined direct and indirect learning

A wireless communications system includes a stochastic pre-distortion actuator configured to receive a carrier-modulated signal and convert the carrier-modulated signal into an output signal. The system includes one or more antennas configured to receive the output signal and transmit the output signal, one or more power amplifiers electrically coupled between the pre-distortion actuator and the one or more antennas and a receiver configured to receive the output signal over-the-air and generate feedback based on the output signal. The pre-distortion actuator is configured to generate the output signal by applying a correction to the carrier-modulated signal that cancels out nonlinearities associated with the one or more antennas and/or the one or more power amplifiers. The pre-distortion actuator is configured based on the feedback.

Growing community of inventors

El Segundo, CA, United States of America

Martin S McCormick