Real-Time Processing of Forward Error Correction Coding for High-Datarate Free-Space Optical Satellite Communication on a Commercial Off-The-Shelf System on Chip

Kurzfassung

Free-space optical communication is a promising technology for the next generation of very-high data rate links between satellites and the Earth as well as between satellites themselves. The OSIRIS program of the German Aerospace Centers (DLR) Institute of Communication and Navigation aims to develop, test, and commercialize optical communication technologies for small satellites used in Earth observation and megaconstellations. Building on the success of DLRs OSIRIS4CubeSat (O4C), the worlds smallest laser terminal, DLR is enhancing the O4C terminal to enable bidirectional optical communication links between CubeSats in the CubeISL project. To improve the optical link performance, forward error correction (FEC) schemes are utilized to correct bit and burst errors introduced e.g. by the atmosphere. Processing of these forward error correction codes however is computationally demanding. While the processing of the FEC coding was performed in advance of a link in O4C, additional near-real-time processing is planned for CubeISL, requiring high throughput FEC coding on the inherently limited computational resources on the CubeSat. This thesis evaluates and optimizes the achievable FEC processing performance on the commercial off-the-shelf System-on-Chip (SoC) that is deployed on the CubeISL satellite. The FEC schemes for encoding and decoding were integrated, profiled and optimized on the SoC. A more than sevenfold increase in throughput is demonstrated, factors that need to be considered for near-real-time processing are discussed and a concept for further improvements is proposed.