Abstract: An illustrated embodiment disclosed herein is a method for downlink scheduling. The method includes scheduling, by a satellite, one or more protocol data units (PDUs) in a slot, determining, by the satellite, whether available capacity of the slot is less than a predetermined threshold, responsive to determining that the available capacity of the slot is not less than the predetermined threshold, scheduling, by the satellite, a second one or more PDUs in the slot, and responsive to determining that the available capacity of the slot is less than that the predetermined threshold, transmitting, by the satellite, the slot to an endpoint. In some embodiments, the one or more PDUs are associated with a first spreading factor (SF). In some embodiments, the first SF is lower than a second SF. In some embodiments, the second one or more PDUs are associated with the second SF.

Abstract: An illustrated embodiment disclosed herein is a method including receiving, by a gateway, a first physical data unit (PDU) of a plurality of PDUs from an endpoint via a first satellite, receiving, by the gateway, a second PDU of the plurality of PDUs from the endpoint via a second satellite, and decoding, by the gateway, a payload from the first PDU and the second PDU.

Abstract: An illustrated embodiment disclosed herein is a method including receiving, by an endpoint, a downlink (DL) PDU from of a plurality of sources, determining, by the endpoint and for each DL PDU, a frequency offset from a reference frequency, selecting, by the endpoint, one of the plurality of sources having a first frequency offset that satisfies an threshold, and sending, by the endpoint, an uplink (UL) PDU to the selected source.

Abstract: An illustrated embodiment disclosed herein is a method for downlink scheduling. The method includes scheduling, by a satellite, one or more protocol data units (PDUs) in a slot, determining, by the satellite, whether available capacity of the slot is less than a predetermined threshold, responsive to determining that the available capacity of the slot is not less than the predetermined threshold, scheduling, by the satellite, a second one or more PDUs in the slot, and responsive to determining that the available capacity of the slot is less than that the predetermined threshold, transmitting, by the satellite, the slot to an endpoint. In some embodiments, the one or more PDUs are associated with a first spreading factor (SF). In some embodiments, the first SF is lower than a second SF. In some embodiments, the second one or more PDUs are associated with the second SF.

Abstract: An illustrated embodiment disclosed herein is a method including receiving, by an endpoint and from a satellite, a downlink (DL) frame including a reduced power portion of the DL frame, measuring, by the endpoint, a signal strength of the reduced power portion of the DL frame, selecting, by the endpoint, an uplink (UL) spreading factor (SF) and a UL transmit (Tx) backoff associated with a target UL Tx power at which to send a UL frame, measuring, by the endpoint, a first rise-over-thermal, sending, by the endpoint and to the satellite, the UL frame including at least one of the UL SF or the first rise-over-thermal, receiving, by the endpoint and from the satellite, a DL physical data unit (PDU) modulated by a DL SF selected by the satellite, and demodulating, by the endpoint, the DL PDU simultaneously at a plurality of SFs.

Abstract: An illustrated embodiment disclosed herein is a method including receiving, by a gateway, a first physical data unit (PDU) of a plurality of PDUs from an endpoint via a first satellite, receiving, by the gateway, a second PDU of the plurality of PDUs from the endpoint via a second satellite, and decoding, by the gateway, a payload from the first PDU and the second PDU.

Abstract: An illustrated embodiment disclosed herein is a method including receiving, by an endpoint and from a satellite, a downlink (DL) frame including a reduced power portion of the DL frame, measuring, by the endpoint, a signal strength of the reduced power portion of the DL frame, selecting, by the endpoint, an uplink (UL) spreading factor (SF) and a UL transmit (Tx) backoff associated with a target UL Tx power at which to send a UL frame, measuring, by the endpoint, a first rise-over-thermal, sending, by the endpoint and to the satellite, the UL frame including at least one of the UL SF or the first rise-over-thermal, receiving, by the endpoint and from the satellite, a DL physical data unit (PDU) modulated by a DL SF selected by the satellite, and demodulating, by the endpoint, the DL PDU simultaneously at a plurality of SFs.

Abstract: An illustrated embodiment disclosed herein is a method including receiving, by an endpoint, a downlink (DL) PDU from of a plurality of sources, determining, by the endpoint and for each DL PDU, a frequency offset from a reference frequency, selecting, by the endpoint, one of the plurality of sources having a first frequency offset that satisfies an threshold, and sending, by the endpoint, an uplink (UL) PDU to the selected source.

Abstract: An illustrated embodiment disclosed herein is a method including maintaining, by a satellite, a plurality of physical data units (PDUs). Each PDU has a corresponding spreading factor (SF). The method includes selecting, by the satellite, a lowest SF, adding, by the satellite, all PDUs associated with the lowest SF to a slot, and determining, by the satellite and until the determination is affirmative, whether available capacity of the slot is less than a predetermined threshold. The method includes, responsive to determining that the available capacity of the slot is not less than the predetermined threshold, selecting, by the satellite, a greater SF and adding, by the satellite, one or more PDUs associated with the greater SF to the slot. The method includes responsive to determining that the available capacity of the slot is less than that the predetermined threshold, sending, by the satellite, the slot to an endpoint.

Abstract: An illustrated embodiment disclosed herein is a method including receiving, by an endpoint, a plurality of swept syncs, each swept sync being on a different channel, measuring, by the endpoint, a received signal power for each of the plurality of swept syncs, determining, by the endpoint, a first swept sync based on the received signal power, interpolating, from the first swept sync, a first channel for sending an uplink (UL) physical data unit (PDU), sending, by the endpoint, the UL PDU on the first channel, and receiving, by the endpoint, a downlink (DL) PDU on a second channel, wherein the second channel is based on the first channel to leverage channel reciprocity.

Abstract: An illustrated embodiment disclosed herein is a method including determining, by an endpoint, a Doppler frequency offset and a first derivative of the Doppler frequency offset, calculating, by the endpoint, a second derivative of the Doppler frequency offset based on an orbital model, and calculating, by the endpoint, a first delta to the Doppler frequency offset and a second delta to the first derivative of the Doppler frequency offset.

Abstract: An illustrated embodiment disclosed herein is a method including correlating, by an endpoint, a first frame and a second frame with a plurality of hypotheses, detecting, by the endpoint, for each correlation of the first frame, a first metric and, for each correlation of the second frame, a second metric, identifying, by the endpoint, a first subset of hypotheses based on the first metric and a second subset of hypotheses based on the second metric, identifying, by the endpoint, pairs of hypotheses, each pair including a first hypothesis from the first subset and a second hypothesis from the second subset. The first hypothesis is same or within a predetermined distance of the second hypothesis. The method includes selecting, by the endpoint and from the pairs of hypotheses, a hypothesis based on the second metric and selecting, by the endpoint, a channel for transmission at which the hypothesis is selected.

Abstract: An illustrative embodiment disclosed herein is a method including determining, by a location server, a satellite constellation, a location of a target endpoint, and a next available time of the target endpoint. The method further includes determining, by the location server, a plurality of candidate satellites based on the satellite constellation, the location of the target endpoint, and the next available time of the target endpoint. The method further includes instructing, by the location server, a ground station to broadcast a downlink signal to the plurality of candidate satellites.

Abstract: An illustrative embodiment disclosed herein is a satellite including a transceiver, a first antenna, a second antenna, and a switch to enable only the first antenna by electrically coupling the first antenna to the transceiver responsive to a satellite constellation having less than a threshold number of satellites and enable only the second antenna by electrically coupling the second antenna to the transceiver responsive to the satellite constellation having greater than the threshold number of satellites.

Abstract: An illustrative embodiment disclosed herein is a method, by a satellite, including sending a downlink signal to a first endpoint and a second endpoint at a first time and receiving a first uplink signal from the first endpoint at a second time. The second time is based on a first delay value calculated by the first endpoint. The method further includes receiving a second uplink signal from the second endpoint at a third time. The third time is based on a second delay value calculated by the second endpoint. The method further includes calculating the first delay value and the second delay value based on one or more identifiers of the first endpoint and the second endpoint, respectively, and an algorithm and determining a first distance between the satellite and the first endpoint and a second distance between the satellite and the second endpoint.

Abstract: An illustrative embodiment disclosed herein is a method including estimating, by an endpoint, a first rate of change of a Doppler frequency offset during a downlink reception from a satellite associated with the Doppler frequency offset and applying, by the endpoint, a second rate of change of the Doppler frequency offset to an uplink transmission to the satellite. The second rate of change of the Doppler frequency offset compensates the first rate of change of the Doppler frequency offset.

Abstract: An illustrative embodiment disclosed herein is a method including determining, by a location server, a satellite constellation, a location of a target endpoint, and a next available time of the target endpoint. The method further includes determining, by the location server, a plurality of candidate satellites based on the satellite constellation, the location of the target endpoint, and the next available time of the target endpoint. The method further includes instructing, by the location server, a ground station to broadcast a downlink signal to the plurality of candidate satellites.

Abstract: An illustrative embodiment disclosed herein is a method, by a satellite, including sending a downlink signal to a first endpoint and a second endpoint at a first time and receiving a first uplink signal from the first endpoint at a second time. The second time is based on a first delay value calculated by the first endpoint. The method further includes receiving a second uplink signal from the second endpoint at a third time. The third time is based on a second delay value calculated by the second endpoint. The method further includes calculating the first delay value and the second delay value based on one or more identifiers of the first endpoint and the second endpoint, respectively, and an algorithm and determining a first distance between the satellite and the first endpoint and a second distance between the satellite and the second endpoint.

Abstract: An illustrative embodiment disclosed herein is a satellite including a transceiver, a first antenna, a second antenna, and a switch to enable only the first antenna by electrically coupling the first antenna to the transceiver responsive to a satellite constellation having less than a threshold number of satellites and enable only the second antenna by electrically coupling the second antenna to the transceiver responsive to the satellite constellation having greater than the threshold number of satellites.

Abstract: An illustrative embodiment disclosed herein is a method including estimating, by an endpoint, a first rate of change of a Doppler frequency offset during a downlink reception from a satellite associated with the Doppler frequency offset and applying, by the endpoint, a second rate of change of the Doppler frequency offset to an uplink transmission to the satellite. The second rate of change of the Doppler frequency offset compensates the first rate of change of the Doppler frequency offset.