Abstract: Approaches for efficient broadcast of satellite ephemeris information or data in NGSO satellite systems, based on Keplerian parametric models of the satellite orbits, are provided. Keplerian orbit parameters are utilized (e.g., parametric orbit models) for improved efficiency in broadcast of ephemeris data over use of point-wise vectors. The linear change and harmonic variations in Keplerian orbit parameters are accounted for, for example, based on the specification of the linear and harmonic terms, increasing accuracy and extending duration of validity of the orbit parameters. Data compression is employed by (i) differential encoding of orbital parameters, and (ii) exploiting the correlation between the harmonic (Fourier) coefficients model of the orbit parameters.

Abstract: A system and method for estimating calibration parameters and locating a Calibration Earth Station (CES) is described. The method may be performed offline. The method includes: providing L×M pilot signal measurements in a matrix R from L CESs and the M feed elements, wherein the matrix R comprises a set of channel coefficients c={c1, c2, . . . , cM}, and k={k1, k2, . . . , kL} perturbations; linking a subset of channel coefficients {c1, c2, . . . , cM} using each of the L CESs; and estimating a relative estimate of the k={k1, k2, . . . , kL} pertubations across the L CESs by using each of the L CESs as a bridging element. In the method, the bridging element provides a strong pilot signal for at least two of the L CESs. A set of criteria for determining locations of CESs have been described. A set of desirable properties for the solution set of L CESs have been disclosed. A combination of inner loop and outer loop methods for determining the final set of optimal locations have been described.

Abstract: Approaches for efficient, dynamic and continuous handover processes, which encompass selection of an optimal path (consisting of a satellite, a satellite beam and carrier frequency set) over which a mobile user terminal (UT) communicates with the radio access network in a mobile satellite communications system, are provided. A set of path factors are determined regarding each of a plurality of communications paths for the UT. A path selection metric (PSM) for each communications path is determined, wherein the PSM for each communications path is determined via a weighted calculation based on the respective set of path factors for the communications path. A decision is made as to whether to perform a handover of the UT from a first of the communications paths to a second of the communications paths, wherein the determination is based on an evaluation performed based at least in part on the PSM.

Abstract: Approaches for efficient, dynamic and continuous handover processes, which encompass selection of an optimal path (consisting of a satellite, a satellite beam and carrier frequency set) over which a mobile user terminal (UT) communicates with the radio access network in a mobile satellite communications system, are provided. A set of path factors are determined regarding each of a plurality of communications paths for the UT. A path selection metric (PSM) for each communications path is determined, wherein the PSM for each communications path is determined via a weighted calculation based on the respective set of path factors for the communications path. A decision is made as to whether to perform a handover of the UT from a first of the communications paths to a second of the communications paths, wherein the determination is based on an evaluation performed based at least in part on the PSM.

Abstract: A system and method for estimating calibration parameters and locating a Calibration Earth Station (CES) is described. The method may be performed offline. The method includes: providing LxM pilot signal measurements in a matrix R from L CESs and the M feed elements, wherein the matrix R comprises a set of channel coefficients c={c1, c2, . . . , cM}, and k={k1, k2, . . . , kL} perturbations; linking a subset of channel coefficients {c1, c2, . . . , cM} using each of the L CESs; and estimating a relative estimate of the k={k1, k2, . . . , kL} pertubations across the L CESs by using each of the L CESs as a bridging element. In the method, the bridging element provides a strong pilot signal for at least two of the L CESs. A set of criteria for determining locations of CESs have been described. A set of desirable properties for the solution set of L CESs have been disclosed. A combination of inner loop and outer loop methods for determining the final set of optimal locations have been described.

Abstract: A satellite system comprises LEO satellites and MEO satellites, and a control plane protocol architecture. The PHY, MAC, MAC/RLC and RRC layers are optimized for satellite environment. When the satellites are not processing satellites, eNB functions are implemented in a satellite gateway, and, when the satellites are processing satellites, protocol architecture in the control plane differ from LTE, as follows: PHY layer is moved to the communicating LEO/MEO satellite on the user link, MAC/RLC, RRC and PDCP are be located in satellite or gateway depending on satellite complexity, and the need to have mesh connectivity between UTs. When the RRC is implemented in the satellite, the RRC is divided into RRC-Lower and RRC-Upper layers. The RRC-L is satellite-based, and handles UT handover. The RRC-U is eNB-based, and handles resource management functions. The RRC-U communicates with the PDCP layer in the eNB to configure security, header and data compression.

Abstract: A satellite system comprises LEO satellites and MEO satellites, and a control plane protocol architecture. The PHY, MAC, MAC/RLC and RRC layers are optimized for satellite environment. When the satellites are not processing satellites, eNB functions are implemented in a satellite gateway, and, when the satellites are processing satellites, protocol architecture in the control plane differ from LTE, as follows: PHY layer is moved to the communicating LEO/MEO satellite on the user link, MAC/RLC, RRC and PDCP are be located in satellite or gateway depending on satellite complexity, and the need to have mesh connectivity between UTs. When the RRC is implemented in the satellite, the RRC is divided into RRC-Lower and RRC-Upper layers. The RRC-L is satellite-based, and handles UT handover. The RRC-U is eNB-based, and handles resource management functions. The RRC-U communicates with the PDCP layer in the eNB to configure security, header and data compression.

Abstract: A method for satellite to satellite handover of a user terminal in a satellite communications network is provided. The UT receives an initial handover message, from a RAN node, including a target frequency for receiving downlink transmissions from the RAN node via a target satellite and a timing correction, and reconfigures its receiver for receipt of the downlink transmissions via the target frequency. The UT decodes the downlink transmissions to determine allocations for a PRACH of the target satellite provided by the downlink transmissions, and transmits a reply handover message to the RAN node, via the PRACH channel, using the timing correction. The UT receives a flow assignment message from the RAN. The UT reactivates hand-over data flows for the target satellite, and transmits a channel configuration complete message to the RAN node, via the PRACH channel, using the timing correction.

Abstract: A system is provided for reducing latency data collection from space-based sensor satellites. A mobile vehicle platform, configured to travel around the Earth, includes a sensor module and a relay satellite terminal. The sensor module monitors certain conditions, circumstances, environments and/or situations occurring on or around, or associated with, the Earth, and generates sensor data resulting from the monitoring. The relay satellite terminal executes data communications with a first of a plurality of satellites while the mobile vehicle platform is in a first area within a communications range of the first satellite, and, upon moving to a second area within a communications range of a second of the plurality of satellites, the relay satellite terminal switches the data communications to the second satellite. The data communications relay the sensor data, via the satellites, to a central processing facility for aggregation, processing, analysis and/or dissemination of the data.

Abstract: A method for synchronization of user terminal (UT) uplink data transmissions to a satellite in a satellite communications system is provided. The UT tracks frame timing and frequency of downlink data transmissions received by the UT from the satellite. The UT estimates a respective timing delay and frequency shift of the downlink data transmissions based on the tracked frame timing and frequency of the downlink data transmissions. The UT receives satellite ephemeris data broadcast by the satellite. The UT synchronizes uplink data transmissions to the satellite based on the estimated timing delay and frequency shift of the downlink data transmissions, the received satellite ephemeris data, and knowledge of a UT position and velocity vectors associated with any movement of the UT.

Abstract: Approaches for efficient broadcast of satellite ephemeris information or data in NGSO satellite systems, based on Keplerian parametric models of the satellite orbits, are provided. Keplerian orbit parameters are utilized (e.g., parametric orbit models) for improved efficiency in broadcast of ephemeris data over use of point-wise vectors. The linear change and harmonic variations in Keplerian orbit parameters are accounted for, for example, based on the specification of the linear and harmonic terms, increasing accuracy and extending duration of validity of the orbit parameters. Data compression is employed by (i) differential encoding of orbital parameters, and (ii) exploiting the correlation between the harmonic (Fourier) coefficients model of the orbit parameters.

Abstract: A method for synchronization of user terminal (UT) uplink data transmissions to a satellite in a satellite communications system is provided. The UT tracks frame timing and frequency of downlink data transmissions received by the UT from the satellite. The UT estimates a respective timing delay and frequency shift of the downlink data transmissions based on the tracked frame timing and frequency of the downlink data transmissions. The UT receives satellite ephemeris data broadcast by the satellite. The UT synchronizes uplink data transmissions to the satellite based on the estimated timing delay and frequency shift of the downlink data transmissions, the received satellite ephemeris data, and knowledge of a UT position and velocity vectors associated with any movement of the UT.

Abstract: A method for satellite to satellite handover of a user terminal in a satellite communications network is provided. The UT receives an initial handover message, from a RAN node, including a target frequency for receiving downlink transmissions from the RAN node via a target satellite and a timing correction, and reconfigures its receiver for receipt of the downlink transmissions via the target frequency. The UT decodes the downlink transmissions to determine allocations for a PRACH of the target satellite provided by the downlink transmissions, and transmits a reply handover message to the RAN node, via the PRACH channel, using the timing correction. The UT receives a flow assignment message from the RAN. The UT reactivates hand-over data flows for the target satellite, and transmits a channel configuration complete message to the RAN node, via the PRACH channel, using the timing correction.

Abstract: A satellite system comprises LEO satellites and MEO satellites, and a control plane protocol architecture. The PHY, MAC, MAC/RLC and RRC layers are optimized for satellite environment. When the satellites are not processing satellites, eNB functions are implemented in a satellite gateway, and, when the satellites are processing satellites, protocol architecture in the control plane differ from LTE, as follows: PHY layer is moved to the communicating LEO/MEO satellite on the user link, MAC/RLC, RRC and PDCP are be located in satellite or gateway depending on satellite complexity, and the need to have mesh connectivity between UTs. When the RRC is implemented in the satellite, the RRC is divided into RRC-Lower and RRC-Upper layers. The RRC-L is satellite-based, and handles UT handover. The RRC-U is eNB-based, and handles resource management functions. The RRC-U communicates with the PDCP layer in the eNB to configure security, header and data compression.

Abstract: Approaches for efficient, dynamic and continuous handover processes, which encompass selection of an optimal path (consisting of a satellite, a satellite beam and carrier frequency set) over which a mobile user terminal (UT) communicates with the radio access network in a mobile satellite communications system, are provided. A set of path factors are determined regarding each of a plurality of communications paths for the UT. A path selection metric (PSM) for each communications path is determined, wherein the PSM for each communications path is determined via a weighted calculation based on the respective set of path factors for the communications path. A decision is made as to whether to perform a handover of the UT from a first of the communications paths to a second of the communications paths, wherein the determination is based on an evaluation performed based at least in part on the PSM.

Abstract: A synchronization approach is provided that compensates for the large Doppler offset of the satellites in a LEO satellite system by exploiting the predictable and deterministic nature of the Doppler component, and thereby simplifies the delay and the Doppler domain uncertainty ranges that the physical layer receivers have to resolve. The compensation is based on the known ephemeris information of the LEO satellite and the known positions of the gateway (GW) and the user terminal (UT) on the ground. Utilizing the deterministic component of the LEO Doppler, the synchronization process continually tracks and compensates for the time-varying offsets between the GW and UT frame timing, frame numbering (FN), symbol timings, and Doppler-induced scaling of center frequency and the signal bandwidth.

Abstract: An apparatus and method for synchronizing communication between systems having different clock rates, is described. The apparatus includes a communication unit, a synchronization unit, and an interface unit. The communication unit receives upstream information and generates a first sample stream representative of the upstream information based on a first clock rate. The synchronization unit converts the first sample stream to a second sample stream based on a second clock rate and in accordance with a predetermined burst plan. The interface unit receives the second sample stream at the second clock rate and outputs it based on the predetermined burst plan.

Abstract: A method and a satellite terminal are provided. The satellite terminal may range over multiple frequencies and may receive, from a satellite gateway, a signal quality indicator with respect to each of the ranged multiple frequencies. Noise and interference for a corresponding frequency are estimated based on at least one of the received signal quality indicators for the corresponding frequency. Path loss is estimated based on multiple received signal quality indicators, each of which is received in response to the satellite terminal transmitting a signal while not performing the ranging process. A transmit power level of the satellite terminal is adjusted for the corresponding frequency based on the estimated path loss and the estimated noise and interference for the corresponding frequency.

Abstract: Approaches for efficient, dynamic and continuous handover processes, which encompass selection of an optimal path (consisting of a satellite, a satellite beam and carrier frequency set) over which a mobile user terminal (UT) communicates with the radio access network in a mobile satellite communications system, are provided. A set of path factors are determined regarding each of a plurality of communications paths for the UT. A path selection metric (PSM) for each communications path is determined, wherein the PSM for each communications path is determined via a weighted calculation based on the respective set of path factors for the communications path. A decision is made as to whether to perform a handover of the UT from a first of the communications paths to a second of the communications paths, wherein the determination is based on an evaluation performed based at least in part on the PSM.

Abstract: Approaches for efficient, dynamic and continuous handover processes, which encompass selection of an optimal path (consisting of a satellite, a satellite beam and carrier frequency set) over which a mobile user terminal (UT) communicates with the radio access network in a mobile satellite communications system, are provided. A set of path factors are determined regarding each of a plurality of communications paths for the UT. A path selection metric (PSM) for each communications path is determined, wherein the PSM for each communications path is determined via a weighted calculation based on the respective set of path factors for the communications path. A decision is made as to whether to perform a handover of the UT from a first of the communications paths to a second of the communications paths, wherein the determination is based on an evaluation performed based at least in part on the PSM.