Amazon Technologies, Inc.

Timothy Leo Gallagher

Pengfei Xia

Runhua Chen

Rod G Fleck

Murali R Krishnan

Torbjorn Larsson

Arunabha Ghosh

Danijela Cabric

Duong Anh Hoang

A satellite constellation provides communication between user terminals (UTs) and ground stations that connect to other networks. Grant-free transmissions allow the UTs access to the satellite uplink as needed. Each UT is assigned a unique preamble that represents a combination of repetition pattern (from a set of patterns) and precoding vectors (from a set of precoding vectors). The repetition pattern specifies two or more uplink slots to transmit the same data. The precoding vectors specify different phase angles for the respective uplink slots. The UT transmits a signal using the preamble, repetition pattern, and precoding vectors. The satellite receives these signals, and stores signal data representative of the signals, including repetitions. Overlapping signals from different UTs received during the same timeslot are separated using successive interference cancellation or a linear equalizer. The recovered signal may then be processed to recover data encoded therein.

System for grant-free transmissions

Technologies directed to grant-free transmission communication methodology and systems are described. One method includes determining first data that is associated with data transmission between a communication device and a first user terminal (UT). The method further includes determining, based on the first data, second data. The second data indicates communication resources associated with an uplink to the communication system that is allocated to the first UT. The second data further indicates that the communication resources are available for sending additional data by other non-scheduled UTs. The method further includes sending the second data to the first UT and receiving third data using the communication resources. The method further includes identifying a first portion of the third data that is associated with data transmission by a second UT. The method further includes identifying a second portion of the third data that is associated with data transmission by the first UT.

Grant-free overlay data transmissions

Technologies directed to co-channel interference detection using a signal correlation test are described. One method includes receiving a radio frequency (RF) signal and generating digital sample corresponding to the RF signal. The method further includes determining a first correlation coefficient using the digital samples, a first value, and a second value. The first value corresponds to a signal lag parameter and the second value corresponds to a cyclic frequency parameter. The method further includes determining a second correlation coefficient using the digital samples, the first value, and a third value corresponding to the cyclic frequency parameter. The second value and the third value are multiples of a fourth value. The method further includes determining, using the first correlation coefficient and the second correlation coefficient, that first RF signal comprises a first portion from a second communication device and a second portion from a third communication device.

Detecting co-channel interference using cyclic autocorrelation test

A constellation of many satellites and associated ground stations provide communication service to user terminals. These devices use modulation techniques such as orthogonal frequency division multiplexing (OFDM) to send large quantities of data. For transmission, a power amplifier increases the amplitude of a waveform modulated in this way. The power amplifier operates more efficiently closer to saturation. However, operation at saturation results in nonlinear distortion, producing unwanted signals and increasing bit error rate. A set of techniques are used to reduce the peak to average power ratio (PAPR) of the waveform provided to the power amplifier. A distortionless technique remaps blocks of bits to reduce the resulting PAPR of that block. Additional techniques may also be progressively applied to reduce PAPR while minimizing adverse consequences such as in-band distortion, out of band emissions, increased bit error rate, and so forth. These techniques may include filtering, peak cancellation, and circular clipping.

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Woodinville, WA, United States of America

Timothy Leo Gallagher