SDN-driven multicast streams with adaptive bitrates for VoIP conferences

Achieving high-quality voice conference calls over the Internet is a difficult task. Heterogeneous mobile devices and network dynamics must be properly managed by multiparty VoIP systems to ensure a good quality of experience. In this paper, we propose a multiparty VoIP system based on SDN technology that uses both multicast distribution and dynamic stream adaptation to optimize the conference call quality for each participant. We define a tree construction algorithm that includes two modes: a minimum spanning tree mode and a shortest path tree mode. We have simulated conference calls with various parameters and results show that a trade-off can be achieved between path latency and bandwidth consumption when using multicasted streams with adaptive bitrates. Compared to a typical multiparty VoIP system, up to two-third bandwidth consumption reduction is possible with only a small increase of the average path latency. Our solution could be leveraged by other types of real-time applications such as online gaming.