Introduction to the File Protection Scheme
Interview with DLR on the FPS development
The new file protection scheme protects big data files stored onboard the satellite against storage and transmission errors, which might occur in optical downlinks. This file protection is achieved through a novel packet level encoding scheme, which is applied offline to the whole file stored on-board the satellite. With this file protection, erroneous or deleted packets of the file can be corrected with a performance close to the theoretical limit (Singleton bound). The encoding and decoding of the file does not need complex computations and is dominated by read and write operations so that even a software implementation on a PC can achieve a high encoding/decoding speed of about 2 Gbit/s.
File Protection Scheme
Application:
The file protection scheme can be applied to files before they are transmitted via optical earth observation downlinks. Physical layer encoding in the PHY layer of the downlink is still needed to correct sporadic errors. The file protection scheme can then correct longer error bursts, as they are expected in optical downlinks.
Performance:
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Correction of long error-bursts (e.g. 10 Mbit up to 200 Mbit long error-bursts)
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Error correction capability: up to 25% erroneous / lost packets
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Offline encoding and decoding of the file
Capabilities:
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Error correction scheme for files transmitted via optical downlinks from earth observation satellites
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Correction of corrupted or lost data produced by up to 200 Mbit (20ms) long outages due to scintillation in optical downlinks
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Compatible with any PHY layer frame formats of the optical downlink, e.g. with Space packets and Transfer frames
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Implementation as a pure software solution for offline encoding and decoding, tested with personal computers
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The decoding computer can be connected to an optical receiver via 10 Gbit/s Ethernet to receive and store the data for offline decoding