Satellite Timing Synchronization via DVB-S2X Feedback
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Solution Overview
Problem
Current satellite communication systems lack a method to synchronize the satellite clock with an exact time of day, leading to inefficiencies in beam hopping operations, which affect the synchronization of satellite switching instants with ground network elements.
Innovation Solution
A closed loop feedback system using a modified DVB-S2X Annex E waveform with timing markers and synchronization patterns is employed to synchronize the satellite switching clock, allowing user terminals to provide feedback on received timing markers to adjust the Outroute signal timing with the satellite switching instants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a beam hopping satellite system is used to flexibly route uplink spectrum to downlink, then bandwidth utilization and network capacity are improved, but timing synchronization between satellite switching instants and ground network elements deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where user terminals detect timing markers in received signals, calculate timing offsets between expected and actual marker positions, and report these offsets to the gateway. The gateway uses this feedback to adjust its transmission timing, thereby maintaining synchronization despite beam hopping operations. This closed-loop feedback system resolves the contradiction by enabling dynamic timing correction that preserves synchronization precision while maintaining the flexible bandwidth utilization benefits of beam hopping.
Solution Approach 2:
The patent embeds timing markers at predetermined positions within the signal structure before transmission. These markers are placed in advance at known locations in the waveform, allowing user terminals to detect them and calculate timing offsets without requiring complex real-time analysis. This preliminary placement of synchronization references enables efficient timing measurement and correction, resolving the contradiction between maintaining synchronization precision and enabling flexible beam hopping operations.
2Adaptability or versatility
If satellite switching instants are made programmable, then operational flexibility is improved, but the ability to synchronize to an exact time of day deteriorates
Solution Approach 1:
The feedback mechanism allows the system to maintain programmable beam hopping schedules while achieving time-of-day synchronization. User terminals continuously measure timing offsets of received markers and report them to the gateway, which adjusts its transmission timing accordingly. This closed-loop control enables the system to synchronize to absolute time references despite using programmable, flexible switching schedules, thereby resolving the contradiction between operational flexibility and time synchronization precision.
Solution Approach 2:
The patent introduces timing markers as intermediary reference signals embedded within the flexible programmable waveform structure. These markers serve as intermediaries that carry absolute timing information through the flexible beam hopping system, allowing ground terminals to extract precise time-of-day synchronization information even when the underlying switching schedule is programmable and flexible. This intermediary mechanism resolves the contradiction by decoupling the flexibility of switching schedules from the precision of time synchronization.
3Measurement precision
If timing markers are embedded in the waveform, then synchronization capability is improved, but waveform complexity increases
Solution Approach 1:
The patent segments the waveform into distinct functional components, including dedicated timing marker positions within the signal structure. By separating the synchronization function into specific marker elements embedded at predetermined locations, the system achieves precise timing measurement without requiring complex modifications to the entire waveform. This segmentation approach resolves the contradiction by localizing the synchronization enhancement to specific waveform elements rather than increasing overall waveform complexity uniformly.
Solution Approach 2:
The timing markers serve multiple functions simultaneously: they provide synchronization references for timing offset measurement, enable acquisition of signal parameters, and support tracking of beam hopping patterns. This multi-functionality allows the waveform to achieve enhanced synchronization capability without proportionally increasing complexity, as the same marker structures fulfill multiple purposes. The universal use of timing markers for various signal processing functions resolves the contradiction between synchronization capability and waveform complexity.
Data Source
AI summary
A system and method for timing synchronization with a modified DVB-S2X waveform for a forward beam hopping satellite is described. The method includes: transmitting a channel including a plurality of beams per a Beam Hopping Time Plan (BHTP), wherein each beam includes a discontinuous signal including a superframe including timing markers and a Beam Hopping Forward Synchronization Pattern (BHFSP); receiving a synchronization information, without a loopback beam, for one of the plurality of beams; determining an adjustment period and an adjusted symbol rate for generation of terrestrial switching instants, based on the synchronization information, for a transmission of the plurality of beams such that at least a portion of a respective BHFSP of one of the beams aligns with one of satellite switching instants; and adjusting a timing and symbol rate of the transmission according to the adjustment period and the adjusted symbol rate, respectively.