Abstract: A constellation of satellites provides communication services to user terminals (UTs). Some UTs may be fixed while others are mobile. Each satellite provides communication services to discrete geographic areas or “spots” on and above the Earth. The mobile UT may operate in various modes. In a normal mode, communication resources within a single spot are allocated to a mobile UT. An obfuscated mode allocates the mobile UT communication resources in many spots, even though the mobile UT is only physically present in one. A whisper mode minimizes transmission from the mobile UT. With the exact location of the mobile UT unknown to the satellites, the mobile UT may send a handover request that is used to schedule a handover to other satellite(s), providing ongoing communication service while the mobile UT moves. In some implementations the handover request is determined in advance. A quiet mode facilitates the mobile UT receiving only.

Abstract: A satellite constellation provides communication between user terminals (UTs) and ground stations that connect to other networks, such as the Internet. Satellites transmit beacon transmissions to particular areas on Earth as particular times. The beacon transmissions include information used by a UT to use a random access channel (RACH) uplink to request communication. Responsive to the request, encryption is established between the satellite and the UT. The satellite may then allocate uplink resources, send data to the UT on a downlink, and so forth. The UT receives additional data about future handovers to other satellites. Based on previously received data the UT may quickly re-establish communication with a satellite after an interruption, such as due to a power outage at the UT. If the previously received data has expired, the UT may again use a beacon transmission.

Abstract: A constellation of satellites provides communication services to user terminals (UTs). Some UTs may be mobile. Each satellite provides communication services to discrete geographic areas or “spots” on and above the Earth. The mobile UT determines it will be moving from a current spot to a destination spot based on one or more of geographic position and the geometry of the spots, or signal strength of received signals from one or more satellites associated with the destination spot. The mobile UT sends a handover request. Responsive to the handover request, communication resources associated with a handover time and the destination spot are allocated to the mobile UT. This information is provided to the mobile UT for use after the handover time. During this process, the exact position of the mobile UT remains unknown to the satellites and associated systems managing the constellation and handover.

Abstract: A satellite provides communication between user terminals (UTs) and ground stations that connect to other networks, such as the Internet. Because the satellite is within range of many UTs at any given time, many UTs are in contention to use an uplink to send upstream data to the satellite. This saturates a random-access channel (RACH) on the uplink. When a UT has data to uplink, it sends a short buffer data status (SBDS) message using the RACH. The minimal size of the SBDS facilitates use of a non-orthogonal multiple access uplink. Based on the SBDS, the satellite allocates a grant to the UT to use the uplink. Additional messages from the UT involving buffer status may be sent using the granted uplink. Unsolicited grants may be issued to the UT based on analysis of uplink and downlink traffic. If needed, the RACH may still be used to request additional grants.

Abstract: A satellite provides communication between user terminals (UTs) and ground stations that connect to other networks, such as the Internet. Because the satellite is within range of many UTs at any given time, many UTs are in contention to use an uplink to send upstream data to the satellite. This saturates a random-access channel (RACH) on the uplink. When a UT has data to uplink, it sends a short buffer data status (SBDS) message using the RACH. The minimal size of the SBDS facilitates use of a non-orthogonal multiple access uplink. Based on the SBDS, the satellite allocates a grant to the UT to use the uplink. Additional messages from the UT involving buffer status may be sent using the granted uplink. Unsolicited grants may be issued to the UT based on analysis of uplink and downlink traffic. If needed, the RACH may still be used to request additional grants.

Abstract: Technologies directed to scheduling transmissions between a satellite system and customer terminals (CTs) with half-duplex (HD) radios are described. A communication system includes a radio, a modem with a HD controller, a downlink (DL) scheduler, and an uplink (UL) scheduler. The HD controller determines a first set of HD CTs that are eligible DL transmissions for a first radio frame and a second set of HD CTs that are eligible for UL transmissions for a second radio frame. The HD controller determines a throughput value and buffer information about each of the first set and the second set of HD CTs. The HD controller determines a first subset of HD CTs for DL scheduling and a second subset of HD CTs for UL scheduling. The DL scheduler schedules radio resources for a first radio frame and the UL scheduler schedules radio resources for a second radio frame.

Abstract: A satellite provides communication between user terminals (UTs) and ground stations that connect to other networks, such as the Internet. Because the satellite is within range of many UTs at any given time, many UTs are in contention to use an uplink to send data to the satellite. Each satellite manages uplink contention by maintaining state data representative of the uplink resources allocated for use. As satellites move, handovers take place, transferring communication services from a first satellite to a second satellite. Before a handover, a first satellite sends state data to a UT. The second satellite is also informed about the UT. After the handover, the second satellite provides the UT with priority access to the uplink to send the state data to the second satellite. The second satellite uses the state data to resume management of the uplink, eliminating the need for time consuming link setup.

Abstract: Techniques for improving the efficiency of transmitting data between devices are described. In an example, a first device transmits first data to a second device during a first time interval, whereby the second device is configured to communicate with the first device in a half-duplex mode. During a second time interval, the first device receives second data from the second device. The first device then determines that the second device transmitted the second data during a third time interval that is between the first time and the second time, and during which a reception of the first data by the second device is expected. The first device then retransmits the first data based at least in part on determining that the second device transmitted the second data during the third time interval.

Abstract: A satellite provides communication between user terminals (UTs) and ground stations that connect to other networks, such as the Internet. Because the satellite is within range of many UTs at any given time, many UTs are in contention to use an uplink to send data to the satellite. Each satellite manages uplink contention by maintaining state data representative of the uplink resources allocated for use. As satellites move, handovers take place, transferring communication services from a first satellite to a second satellite. Before a handover, a first satellite sends state data to a UT. The second satellite is also informed about the UT. After the handover, the second satellite provides the UT with priority access to the uplink to send the state data to the second satellite. The second satellite uses the state data to resume management of the uplink, eliminating the need for time consuming link setup.

Abstract: A satellite provides communication between user terminals (UTs) and ground stations that connect to other networks, such as the Internet. Because the satellite is within range of many UTs at any given time, many UTs are in contention to use an uplink to send upstream data to the satellite. Contention for the uplink may be managed by sending grants that allocate a portion of the uplink time and frequency resources to individual UTs. A UT serviced by the satellite uses information based on the grants to determine whether upstream data from a user device connected the UT should be accepted for future transmission promised to deliver specified quality of service to the user device. Acting as a distributed system, each UT may decide to approve upstream data based on one or more factors, such as source address, destination address, header flags, predicted radio availability, and so forth.

Abstract: Satellites provide communication between devices such as user terminals (UTs) and ground stations that are in turn connected to other networks, such as the Internet. Latency for signals to and from the satellite can introduce delays due at least in part to propagation time. The latency adversely interacts with data transfers that result in responses from the UT. Downstream data to the UT is processed to determine if a response is expected. Header data is associated with the downstream data that is sent to the satellite. A resource scheduler onboard the satellite uses the header data to provide a prospective grant to the UT to send the expected response. The UT receives the downstream data, response data such as an acknowledgement is generated, and the response data is sent to the satellite using the prospective grant. The system substantially reduces the latency associated with responsive traffic and improves overall throughput.

Abstract: Satellites provide communication between devices such as user terminals and gateways to other networks, such as the Internet. Non-geosynchronous orbit satellites move relative to user terminals, passing in and out of communication over time. The user terminal itself may also move. Each satellite maintains a plurality of subbeams, each directed towards a different area on the Earth for a portion of an orbit. Based on a predicted location for the user terminal, a handover from a first subbeam to a second subbeam is determined. To minimize disruption due to the handover, communication resources associated with the second subbeam are allocated and provided to the user terminal and the satellite in advance. At the handover time, if the user terminal is within a threshold distance of the predicted location, the user terminal may transition to using the second subbeam. Otherwise, the user terminal may continue to use the first subbeam.