Reducing End-to-End Delays in WebRTC using the FSE-NG Algorithm for SCReAM Congestion Control

The 2020 Corona pandemic has shown that on-line real-time multimedia communication is of vital importance when regular face-to-face meetings are not possible. One popular choice for conducting these meetings is the open standard WebRTC which is implemented in every major web browser. Even though this technology has found widespread use, there are still open issues with how different congestion control (CC) algorithms of Media- and DataChannels interact. In 2018 we have shown that the issue of self-inflicted queuing delay can be mitigated by introducing a CC coupling mechanism called FSE-NG. Originally, this solution was only capable of linking DataChannel flows controlled by TCP-style CCs and MediaChannels controlled by NADA CC. Standardization has progressed and along with NADA, IETF has also standardized the RTP CC SCReAM. This work extends the FSE-NG algorithm to also incorporate flows controlled by the latter algorithm. By means of simulation, we show that our approach is capable of drastically reducing end-to-end delays while also increasing RTP throughput and thus enabling WebRTC communication in scenarios where it has not been applicable before.