Hybrid Satellite-Terrestrial Link Synchronization Method

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Solution Overview

Problem

Current telecommunications systems for drone control-command face challenges in synchronizing satellite and terrestrial network communications, particularly in ensuring reliable and continuous connectivity with low latency and high availability, especially when using TDMA or WCDMA access modes or waveforms with limited delay tolerance.

Innovation Solution

A method is proposed to synchronize the time references of communication networks, allowing simultaneous use of satellite and terrestrial links by transmitting synchronization signals between stations and user terminals, calculating time intervals to adjust transmission times, ensuring that signals from both networks arrive synchronously at the user terminal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traffic is transmitted in parallel via both satellite and terrestrial networks, then service availability and continuity are maintained during network failures, but bandwidth occupation and equipment cost increase

Engineering Contradiction:

Improveservice availabilityVSAvoidbandwidth occupation

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The system pre-calculates and stores propagation delay differences between satellite and terrestrial networks during normal operation. When a network failure occurs, the pre-calculated timing information is immediately applied to the surviving network, enabling seamless failover without requiring continuous dual-network transmission. This maintains high availability while reducing bandwidth occupation during normal operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention dynamically adjusts transmission timing parameters based on the operational state of networks. During normal operation, timing is optimized for parallel transmission efficiency. During failure conditions, timing parameters are automatically adjusted to compensate for single-network operation, maintaining synchronization without requiring continuous high-bandwidth dual-network transmission.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If failure detection and communication reestablishment protocols are implemented, then communication reliability is improved, but system latency and latency jitter increase

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidsystem latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system pre-establishes timing relationships and propagation delay compensation values during normal operation. When failure occurs, these pre-computed values are immediately applied without requiring protocol exchange delays, eliminating the latency penalty typically associated with failure detection and reestablishment procedures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors network status and automatically adjusts transmission timing based on real-time conditions. This feedback mechanism enables rapid adaptation to network failures without requiring lengthy protocol exchanges, maintaining low latency while ensuring communication reliability through automatic timing adjustment.

Inventive Principle:

Principle #23Feedback

3Reliability

If protocol exchanges are performed for communication reestablishment, then communication reliability is improved, but network congestion and latency increase due to peak usage

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidnetwork throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Timing synchronization information is pre-calculated and stored during normal operation, eliminating the need for protocol exchanges during failure recovery. This preliminary preparation ensures that failover occurs immediately without generating network traffic peaks that would cause congestion and reduce overall network productivity.

Inventive Principle:

Principle #10Preliminary action

4Manufacturing precision

If time references of terrestrial station are adjusted to synchronize with satellite station, then signal arrival synchronization at user terminal is achieved, but transmission timing coordination complexity increases

Engineering Contradiction:

Improvesignal arrival synchronizationVSAvoidtransmission timing coordination

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The satellite station serves as a central time reference intermediary. The terrestrial station adjusts its transmission timing based on synchronization signals from the satellite station, using the satellite as a mediator to coordinate timing across the hybrid network. This approach achieves precise signal arrival synchronization while centralizing timing coordination logic, preventing excessive complexity at the terrestrial station.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3038275B1Method for synchronising signals in a satellite-terrestrial link and associated architecture

Publication Date: 2020.01.22 THALES SA

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AI summary

A method for synchronizing message transmission in a communication system comprising a user terminal (140), a primary communication network (110) including a first station (111), and a secondary communication network (120) including a second station (121), said method consisting of an exchange of synchronization signals enabling the calculation of an offset to be applied to the transmission time of messages sent by said second station so that the messages transmitted by the first and second stations are received synchronously by the user terminal. A communication system implementing the invention.