Space Exploration Technologies Corp.

Spatiallink Corporation

Chen Chen

Peter J Worters

Yashodhan A Dandekar

Phillip E Barber

Darshan Purohit

Pavel Chikulaev

David Sacks

Jeffrey C Strait

Martin S McCormick

Ramakrishna Akella

Khasim Shaheed Shaik Mahammad

Jayasuryan V Iyer

Torbjorn Larsson

Ronald Gottula

Alazar Tamrat

Stephan O Roche

Philip J Treigherman

Sergii Ziuzin

Vladimir Skuratovich

Andrei Pushkin

Qiang Li

Systems, methods, and non-transitory media are provided for low latency handovers. An example method can include receiving, by a user terminal associated with a cell served by a satellite, a schedule of communications between the user terminal and one or more satellites, wherein the one or more satellites comprises the satellite and a different satellite, and wherein the schedule of communications is obtained by the user terminal from the satellite; requesting, based on the schedule, a handover from a beam of the satellite to a different beam of one of the satellite or the different satellite; performing the handover from the beam of the satellite to the different beam of the one of the satellite or the different satellite; and after the handover, transmitting, by the user terminal, one or more packets via the different beam of the one of the satellite or the different satellite.

Low latency schedule-driven handovers

A method of operating an uplink scheduler as part of a medium access control scheduler on a satellite includes selecting, from a plurality of user terminals, a first number of zero-bandwidth request user terminals from the plurality of user terminals, selecting, from the plurality of user terminals, a second number of non-zero-bandwidth request user terminals from the plurality of user terminals, binning the second number of non-zero-bandwidth request user terminals into a plurality of bins based on a respective bandwidth requirement for each non-zero-bandwidth request user terminal and based on a minimum user terminal grant and allocating, according to a grant allocation algorithm, a respective grant of radio resources in an uplink frame to each user terminal of the plurality of user terminals into a respective bin of the plurality of bins in an order associated with increasing bandwidth needs. A downlink scheduler is also disclosed.

System and method of providing a medium access control scheduler

A method for downlink link adaptation includes receiving, from a satellite and at a user terminal, a first data packet data unit according to a first downlink modulation and coding scheme (MCS), computing error vector magnitude data associated with the first data packet data unit, generating, based on one or more of the error vector magnitude data, user terminal signal-to-noise-ratio feedback based on a constant times a previous user terminal signal-to-noise-ratio and a current user terminal signal-to-noise-ratio, and transmitting an uplink packet data unit having a downlink block error rate and the user terminal signal-to-noise-ratio feedback. A satellite runs a link adaptation algorithm based on the user terminal signal-to-noise-ratio feedback and block error rate to generate a second downlink MCS. The method includes receiving at the user terminal a second data packet data unit according to the second downlink MCS for the satellite-to-user-terminal downlink. Uplink link adaptation is also disclosed.

System and method of providing an adaptive modulation and coding scheme

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 user terminal includes a communication module (CM) configured to generate an initial network entry request; an antenna assembly configured to find, in response to the initial network entry request, a satellite based on a search of a sky. The search of the sky includes sequentially changing a beam pointing direction of the antenna assembly. The satellite is assigned to downlink to a geographic cell associated with the user terminal. The user terminal includes a media access control (MAC) layer component configured to generate an uplink radio frame including a random access channel (RACH) request associated with the initial network entry request at a particular portion of the uplink radio frame for the satellite.

Initial network entry to a communications system

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 low latency handovers. An example method can include receiving, by a satellite, a schedule of communications between the satellite and one or more gateways; requesting, based on the schedule, a handover from a link between the satellite and a gateway to a different link between the satellite and the gateway or a different gateway; prior to a completion of the handover, processing packets bicasted over the link between the satellite and the gateway and the different link between the satellite and the gateway or the different gateway; performing the handover from the link between the satellite and the gateway to the different link between the satellite and the gateway or the different gateway; and after the handover, transmitting, by the satellite, one or more packets via the different link between the satellite and the gateway or the different gateway.

A method for downlink link adaptation includes receiving, from a satellite and at a user terminal, a first data packet data unit according to a first downlink modulation and coding scheme (MCS), computing an error vector magnitude data associated with the first data packet data unit, generating, based on one or more of the error vector magnitude data, user terminal signal-to-noise-ratio feedback based on a constant times a previous user terminal signal-to-noise-ratio and a current user terminal signal-to-noise-ratio, and transmitting an uplink packet data unit having a downlink block error rate and the user terminal signal-to-noise-ratio feedback. A satellite runs a link adaptation algorithm based on the user terminal signal-to-noise-ratio feedback and block error rate to generate a second downlink MCS. The method includes receiving at the user terminal a second data packet data unit according to the second downlink MCS for the user terminal. An uplink link adaptation algorithm is also disclosed.

In an embodiment, a user terminal includes a connection manager component configured to generate an initial network entry request; an antenna assembly communicatively coupled to the connection manager and configured, in response to the initial network entry request, to find a satellite based on a search of a sky, wherein the satellite comprises a satellite assigned to downlink to a geographic cell associated with the user terminal; and a media access control (MAC) layer component communicatively coupled to the connection manager, the MAC layer component configured to generate an uplink radio frame including a random access channel (RACH) request associated with the initial network entry request at a particular portion of the uplink radio frame for the satellite, wherein the particular portion is selected by the MAC layer component from among a plurality of portions of the uplink radio frame.

Systems, methods, and non-transitory media are provided for low latency handovers. An example method can include receiving, by a user terminal associated with a cell served by a satellite, a schedule of communications between the user terminal and one or more satellites; requesting, based on the schedule, a handover from a beam of the satellite to a different beam of one of the satellite or a different satellite; processing packets transmitted over the beam of the satellite and/or the different beam of the one of the satellite or the different satellite; performing the handover from the beam of the satellite to the different beam of the one of the satellite or the different satellite; and after the handover, transmitting, by the user terminal, one or more packets via the different beam of the one of the satellite or the different satellite.

A Dual-mode forward path PLL system and method are disclosed. The forward path PLL system includes a phase frequency detector (PFD) circuit including a first input node a second input node, a first output node a second output node, where the PFD receives a first input signal, a second input signal and generates a first output signal and second output signal, and where the first input signal is a reference frequency signal and the second input signal is a divided frequency value signal, a charge pump circuit including a third input node, a fourth input node and a third output node, where the third input node and the fourth input node are coupled to the first output node and the second output node of the PFD and where the Charge pump is programmable; and a loop filter circuit including a fifth input node and fourth output node, where the fifth input node is coupled to the third output node of the charge pump and where the loop filter circuit is programmable. In some aspects, the up-side switch and the down-side switch are current sources and the divided frequency value is signal is a fractional frequency value signal.

Growing community of inventors

Irvine, CA, United States of America

Chen Chen