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.

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.

Systems and methods are described for using opportunistically delayed delivery of content to address sub-optimal bandwidth resource usage in network infrastructures that allow subscribers to share forward link resources. According to some embodiments, content is identified as delayable and assigned to a delaycast queue and/or service flow. For example, a server system of a satellite communications system identifies content that can be delayed to exploit future excess link capacity through multicasting and to exploit subscriber-side storage resources. Some implementations attempt to exploit any excess link resources at any time, while others exploit unused bandwidth only during certain times or when a certain threshold of resources is available. Various embodiments also provide content scoring and/or other prioritization techniques for optimizing exploitation of the delaycast queue.

A satellite communication system comprises one or more non-geostationary satellites. Each satellite is configured to provide a plurality of spot beams. The polarizations of the spot beams are laid out on each satellite so that terminals have a constant polarization as the field of regard traverses the terminal location.

A method for uplink and downlink scheduling in a satellite long-term evolution (LTE) network includes receiving, at a satellite base station, a scheduling request from a terminal device. The method further includes transmitting an uplink and downlink grant to the terminal device with an initial allocation that supports the configured data rate. User data is sent and received from the terminal device based on this initial allocation without continually sending grants to the terminal device. The method also supports changes to the persistent allocation based on updated user traffic requirements as indicated by the terminal device.

Systems and methods are described for using opportunistically delayed delivery of content to address sub-optimal bandwidth resource usage in network infrastructures that allow subscribers to share forward link resources. According to some embodiments, content is identified as delayable and assigned to a delaycast queue and/or service flow. For example, a server system of a satellite communications system identifies content that can be delayed to exploit future excess link capacity through multicasting and to exploit subscriber-side storage resources. Some implementations attempt to exploit any excess link resources at any time, while others exploit unused bandwidth only during certain times or when a certain threshold of resources is available. Various embodiments also provide content scoring and/or other prioritization techniques for optimizing exploitation of the delaycast queue.

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.

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.

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.

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.