Hughes Network Systems, LLC

Highes Network Systems, LLC

Deepak Manohar Arur

Channasandra S Ravishankar

Nassir Benammar

Yash Vasavada

John Corrigan

Gaguk Zakaria

Michael I Parr

Rajeev Gopal

Charles A Barnett

John Leonard Border

Robert James Torres

Anthony Robert Noerpel

James Jehong Jong

Matthew Mario Butehorn

Patrick Stevens

Craig Schweinhart

Xiaoling Huang

Daniel Friedman

Mangala Kannan

Harish Ramchandran

Neil H Tender

Ken Burrell

Tariq Muhammad

Steve Mirra

Peter Lin

Subramanya Bayar Krishna

Gautham Bharadwaj

Michael Parr

Embodiments disclosed herein relate generally to techniques for mitigating blockages associated with satellite systems. More specifically, techniques disclosed herein, describe solutions for minimizing service interruption during satellite handover. One or more blockages associated with one or more user terminals that connect to a satellite system may be determined by various means. Utilizing those blockages, handover times for the one or more user terminals may be determined such that service interrupts may be minimized.

Systems for mitigating service interrupts in satellite systems

Systems and methods for facilitating handover reduction in satellite systems are disclosed. A system may include a processor and a memory storing instructions, which when executed by the processor, may cause the processor to detect a user terminal that is selected for a handover procedure. The handover procedure may facilitate a switch from a source beam to a target beam. Based on input data, the processor may evaluate an ideal time value pertaining to a pre-defined time instance at which a scheduled handover is to be performed. The scheduled handover may correspond to at least one of a scheduled change in operating frequency within same beam or a scheduled feeder link handover due to a change in gateway communicating with the satellite. Based on the evaluation and the input data, the processor may estimate an optimized time value that pertains to an optimized time instance associated with an expected handover reduction.

Handover reduction in satellite communication systems

A user terminal (UT) for a mobile satellite communications system, and an associated method for managing tracking areas for such a UT is provided. When initiating establishment of a radio connection, the UT transmits a connection request message to a satellite gateway (SGW) of the mobile satellite communications system, where the connection request message includes position information identifying a current location of the UT. The UT processes a connection setup message received in response to the connection request message, where the connection setup message includes a first tracking area identifier (TAID) that identifies a one of a plurality of tracking areas that is associated with the current location of the UT. The UT transmits a connection complete message to the SGW, together with an attach request message for a core network of the mobile satellite communications system, which includes the first TAID.

Approaches for high speed global packet data services for LEO/MEO satellite systems

Methods, systems, and apparatus, including computer-readable media, for location management for satellite systems. In some implementations, a controller of a satellite network system receives location data from a user terminal and registers the user terminal in a mobility area with a core network. The controller updates a mapping between satellite beams and mobility areas as the satellite beams move along the ground with respect to the mobility areas, then uses the updated mapping to communicate with the user terminal using an appropriate satellite beam. In some implementations, a controller of a satellite network system determines a mapping of satellite beams to mobility areas, and broadcasts, for each of multiple satellite beams, a message indicating (i) a set of mobility areas that are at least partially covered by the satellite beam and (ii) an indication of boundaries of the mobility areas in the set of mobility areas.

Location management for satellite systems

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. An efficient transport mechanism entails classification of information in Classes with different repetition/update rates based on information types, significantly reducing required broadcast/update data rates while allowing for a wide variation in the orbit orientation.

System and method for efficient broadcast of satellite constellation ephemeris information

A method for prediction of UT handovers in a satellite communications network is provided. Optimal characteristics regarding the beams of satellites and regarding a one UT are determined. For each of a plurality of the satellite beams, for each of a plurality of instants of time t, an estimated signal strength as seen at the UT is determined, wherein each estimated signal strength is determined based on the optimal at the respective time t. A next instant of time tis determined at which the estimated signal strength for a candidate beam that is within the view of the UT is greater than or equal to the estimated signal strength for the satellite beam that is currently servicing the UT. A handover of the UT, at the time t, from the satellite beam that is currently servicing the one UT to the candidate beam is determined.

User terminal handover prediction in wireless communications systems with nonstationary communications platforms

A base station computer that includes a processor and memory storing instructions executable by the processor is described. The processor may be programmed to: determine a geographic position of a user terminal (UT); store the position in the memory; determine to page the UT; correlate a satellite beam based on the position; and page the UT via the satellite beam.

Satellite paging efficiency

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.

Apparatus and method for efficient handover for low earth orbit (LEO) satellite systems

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.

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.

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.

Apparatus and method for network level synchronization in multiple low earth orbit (LEO) satellite communications systems

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.

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Vienna, VA, United States of America

Deepak Manohar Arur