Split Hub Timing Synchronization for Satellite Networks
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Solution Overview
Problem
In split hub VSAT networks, maintaining synchronization timing between geographically distant transmission and internet access equipment, such as between an aircraft and ground-based equipment, is challenging due to the lack of time markers in standard DVB-S2 Outroute signals, requiring precise estimation of delays to ensure remote terminals transmit bursts within narrow time windows.
Innovation Solution
A Timing Synchronization Application (TSA) provides synchronization by transmitting Superframe Numbering Packets (SFNP) with estimated delays, using an estimated closed loop timing algorithm to adjust for ranging values and propagation times, ensuring remote terminals align their transmission with the relay's time reference within tens of microseconds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transmission equipment is placed geographically remote from traffic access equipment (e.g., on aircraft while access equipment remains on ground), then communication coverage and flexibility are improved, but synchronization timing accuracy deteriorates due to vast distances and movement
Solution Approach 1:
The patent introduces a Timing Synchronization Application (TSA) as an intermediary component that acts as a time server, providing timing reference information to remote terminals. This mediator enables accurate synchronization despite the geographical separation between transmission equipment and ground-based access equipment by establishing a dedicated timing reference system that operates independently of the physical distance.
Solution Approach 2:
The system implements feedback mechanisms where the TSA continuously provides timing reference information to remote terminals, and the system adjusts for propagation delays and movement effects based on measured ranging values. This closed-loop feedback ensures that synchronization timing accuracy is maintained even as the relative positions of aircraft and ground equipment change.
2Adaptability or versatility
If standard DVB-S2 Outroute signals are used without time markers, then compatibility with existing communication standards is maintained, but timing synchronization capability is lost
Solution Approach 1:
The patent segments the communication system into distinct functional components: the TSA (timing synchronization function) and the DVB-S2 communication function. By separating these functions, the system can maintain compatibility with standard DVB-S2 Outroute signals while adding dedicated timing synchronization capability through the TSA's Superframe Numbering Packets (SFNP), without requiring modification to the underlying communication standard.
Solution Approach 2:
The Timing Synchronization Application serves multiple functions: it provides timing reference information, transmits Superframe Numbering Packets for synchronization, and enables remote terminals to calculate propagation delays. This multi-functional component adds timing synchronization capability to the existing DVB-S2 system without replacing or modifying the core communication protocol.
3Productivity
If remote terminals must transmit bursts within narrow time windows, then communication efficiency is improved, but the complexity of maintaining synchronization increases over vast distances
Solution Approach 1:
The system performs preliminary actions by having the TSA pre-calculate and provide timing reference information before actual data transmission occurs. Remote terminals use this advance timing information to pre-synchronize their transmission bursts, ensuring they fall within the required narrow time windows without requiring complex real-time adjustment mechanisms during transmission.
Data Source
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AI summary
A split gateway hub for a bent-leg communication system is disclosed. The gateway hub includes: a modulator to modulate a bit stream into a signal to be transmitted to a remote terminal via a radio frequency (RF) signal; a Time Synchronization Application (TSA), geographically co-located with the modulator, to provide timing reference and synchronization to the remote terminal; a network access component to provide traffic for the bit stream; and an Inroute Group Manager (IGM) to manage the traffic to and from the remote terminal. In the split gateway hub, the IGM is disposed geographically remote from either the TSA or from the network access component, and the bent-leg communication system uses a satellite or a High Attitude Platform (HAP) for relaying the RF signal.