Assessing the Interplay between WebRTC and QUIC Congestion Control Algorithms

In the last years, real-time media transport using QUIC has aroused general interest. QUIC now features a datagram mode (congestion control but no loss recovery) along the legacy stream mode. Ongoing research is studying protocol mechanisms to transport media with QUIC to build a new streaming protocol or to map existing ones like RTP onto QUIC. Our work focuses on the transport of RTP packets generated by WebRTC over QUIC and investigates the resulting in-teraction of the QUIC and WebRTC congestion control algorithms. We performed extensive experiments to study various combinations of congestion control algorithms at the QUIC and WebRTC levels. We observed that in a low latency setup, e.g. FTTH, using the stream mode of QUIC pays off as it hides losses to WebRTC, and hence maintaining the maximum video quality otherwise lost. For higher latency scenarios, the datagram mode with an appropriate QUIC level transport pro-tocol offers good performance, even though in case of severe changes of the channel conditions, the WebRTC mechanism takes control of the situation by tuning the encoder rate.