CubeSat Optical File Transfer Frames for Intermittent Downlinks

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing file transfer methods for CubeSats using Free Space Optical (FSO) channels face challenges due to atmospheric effects, limited processing power, and resource constraints, leading to data loss and interoperability issues, while traditional protocols like CFDP and (S)FTP are not suitable for intermittent and asynchronous space links.

Innovation Solution

A method compliant with the CCSDS standard that fragments files into Start, Intermediate, and End Transfer Frames, using adapted CCSDS TM Synchronization and Channel Coding with stronger codes, deep interleaving, and periodic synchronization symbols, embedding file information in secondary headers, and optionally using ARQ for reliable delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional file transfer protocols like CFDP or (S)FTP are used on CubeSats, then file transfer functionality is provided, but processing power and resources are excessively consumed

Engineering Contradiction:

Improvefile transfer functionalityVSAvoidprocessing power consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the essential file transfer functionality from complex protocols like CFDP, implementing a lightweight custom protocol that provides core file transfer capabilities without the overhead of comprehensive protocol features. This removes unnecessary processing requirements while maintaining essential functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs simple, lightweight data structures and protocol elements that require minimal processing resources. Rather than implementing complex, reusable protocol stacks, it uses simplified message formats and transfer mechanisms that consume minimal energy while achieving the transfer objective.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If ground station diversity is implemented to overcome cloud interference, then transmission reliability is improved, but system complexity and interoperability requirements increase

Engineering Contradiction:

Improvetransmission reliabilityVSAvoidnetwork complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a universal communication protocol that can operate across multiple ground stations with different configurations. The protocol design ensures compatibility and interoperability among diverse ground station infrastructures, allowing the same protocol to function reliably across the network without requiring station-specific adaptations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If strong Forward Error Correction codes are used to overcome atmospheric effects, then data integrity is improved, but overhead and processing requirements increase

Engineering Contradiction:

Improvedata integrityVSAvoiddata overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent adapts the Forward Error Correction code parameters specifically for optical communication channels, optimizing the balance between error correction capability and overhead. By tuning code rates and block sizes appropriately for the optical channel characteristics, it achieves robust error correction while minimizing the impact on data throughput and processing requirements.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If deep interleaving is applied to correct burst errors from atmospheric turbulence, then error correction capability is improved, but processing time and complexity increase

Engineering Contradiction:

Improveerror correction capabilityVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent implements deep interleaving selectively for specific types of errors and channel conditions rather than applying it universally to all data transmissions. By using interleaving only when atmospheric turbulence is detected or when error patterns indicate its necessity, it achieves strong error correction capability while minimizing unnecessary processing time for clear channel conditions.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12506534B2Method for data transmission from a spacecraft to ground via a free space optical channel

Publication Date: 2025.12.23 DEUTSCHES ZENTRUM FÜR LUFT UND RAUMFAHRT E V

AI summary

The method for file transmission from a spacecraft to ground via a Free Space Optical channel comprises the use of the Consultative Committee for Space Data Systems (CCSDS) standard with assigning a File ID in the Secondary Header and dividing the transmission of the file into several fractions. The type of fraction, namely Start Transfer Frame, Intermediate Transfer Frame, or End Transfer Frame is identified in the Secondary Header. Also, the File ID, File length, and Name of the file is included in the Secondary Header of the Start Transfer Frame while information about the File ID is included also in the other two types Transfer Frames.