When BBR beats FEC coded CUBIC flows over SATCOM

This paper assesses the benefits of using Sliding Windows Forward error codes (SWF) to protect transport protocol sessions over a SATCOM link within IP tunnels. We consider two commonly deployed protocols and congestion control algorithms : TCP/CUBIC, currently deployed by default inside the most recent OS kernels, and QUIC/BBR implementation named Picoquic. Our objective is to evaluate the performance of these protocols in challenging SATCOM environments and to assess if SWF can contribute to improve their performance. We consider two different scenarios based on real loss mobility patterns played over the OpenSAND satellite emulator. Results show that using SWF tunnels can hide losses to a CUBIC server: this reduces the download time of 20MB by more than 90 %. However, the main finding is that SWF does not contribute to the download time reduction for BBR, making its deployment ineffective. We conclude that the use of BBR over SATCOM could be an efficient way to perform communications over unreliable links, resulting from a high mobility context for instance, considering that BBR flows are managed by an adequate QoS allocation.