Abstract: A communications system may include a satellite and user equipment (UE) devices. When the UE devices have uplink (UL) packets to transmit, each UE device may randomly select a time slot within a finite time window associated with a time reference of the satellite. The UE device may identify a path length between itself and the satellite and may generate a timing advance based on the path length, the time reference, and the time slot. The satellite may begin to receive the UL packets within the time window and may search received signals over the time window to identify the UL packets. The satellite may recover data payloads from the identified UL packets and may pass the recovered data payloads up a protocol stack. By limiting the search to the time window, the satellite may correctly distinguish the UL packets while using a minimal amount of processing resources.

Abstract: A communications system may include user equipment (UE) devices, communications satellites, gateways, and a terrestrial network. The UE devices may receive broadcast signals from the constellation. The UE devices may transmit registration requests to the gateways via the satellites in response to the broadcast signals. The registration requests may include information identifying the geographic locations of the UE devices and may include two-line element (TLE) identifiers. A scheduler on the terrestrial network may receive forward link traffic requests for the UE devices, each with a corresponding priority. The scheduler may also receive satellite information that includes thermal constraints, position information, and power information associated with the satellites. The scheduler may generate forward link traffic grants for the UE devices based on the forward link traffic requests, the thermal constraints, the TLE versions, the geographic locations, and the priorities.

Abstract: A communications system may include user equipment (UE) devices, communications satellites, gateways, and a terrestrial network. The UE devices may receive broadcast signals from the constellation. The UE devices may transmit registration requests to the gateways via the satellites in response to the broadcast signals. The registration requests may include information identifying the geographic locations of the UE devices and may include two-line element (TLE) identifiers. A scheduler on the terrestrial network may receive forward link traffic requests for the UE devices, each with a corresponding priority. The scheduler may also receive satellite information that includes thermal constraints, position information, and power information associated with the satellites. The scheduler may generate forward link traffic grants for the UE devices based on the forward link traffic requests, the thermal constraints, the TLE versions, the geographic locations, and the priorities.

Abstract: A communications system may include user equipment (UE) devices, communications satellites, gateways, and a terrestrial network. The UE devices may receive broadcast signals from the constellation. The UE devices may transmit registration requests to the gateways via the satellites in response to the broadcast signals. The registration requests may include information identifying the geographic locations of the UE devices and may include two-line element (TLE) identifiers. A scheduler on the terrestrial network may receive forward link traffic requests for the UE devices, each with a corresponding priority. The scheduler may also receive satellite information that includes thermal constraints, position information, and power information associated with the satellites. The scheduler may generate forward link traffic grants for the UE devices based on the forward link traffic requests, the thermal constraints, the TLE versions, the geographic locations, and the priorities.

Abstract: A communications system may include user equipment (UE) device, satellites, and a gateway. The UE and gateway may perform implicit handover in which the UE and gateway independently identify the same serving satellite using ephemeris data, without additional signaling overhead. The UE may also characterize its channel conditions. When insufficient, the UE may transmit an explicit handover message to the gateway via a different satellite visible to the UE. The explicit handover message may include a satellite identifier and a lock bit. The gateway may use the satellite identifier to convey wireless data with the UE via the different satellite during the next cycle. The gateway may use the lock bit to know how to perform handover away from the different cycle during subsequent cycles. In this way, the UE may direct handover, given that the gateway has no knowledge of the channel condition at the UE.

Abstract: Frequency spectrum of wireless transmission signals are allocated based on availability and regulatory requirements. To ensure transmission signals are within designated channel boundary, user equipment utilizes processing circuitry coupled to a transceiver to pre-compensate for estimated frequency shift at the time of transmissions. Certain guard bands are provided such that the actual transmission signals with the frequency pre-compensation are within the designated channel boundary. Additionally, or alternatively, the user equipment utilizes the processing circuitry to pre-compensate for estimated time shift based on a crystal drift using temperature measurement.

Abstract: A communications system may include a satellite and user equipment (UE) devices. When the UE devices have uplink (UL) packets to transmit, each UE device may randomly select a time slot within a finite time window associated with a time reference of the satellite. The UE device may identify a path length between itself and the satellite and may generate a timing advance based on the path length, the time reference, and the time slot. The satellite may begin to receive the UL packets within the time window and may search received signals over the time window to identify the UL packets. The satellite may recover data payloads from the identified UL packets and may pass the recovered data payloads up a protocol stack. By limiting the search to the time window, the satellite may correctly distinguish the UL packets while using a minimal amount of processing resources.