MPTCP meets FEC: Supporting Latency-Sensitive Applications over Heterogeneous Networks

TCP has gone through numerous updates over the past years to provide performance enhancement under diverse network conditions. However, with respect to losses, little can be achieved with legacy TCP recovery mechanisms. Both Fast Retransmission (FR) and Retransmission Timeout (RTO) take at least one extra RTT to perform and this might impact the performance of latency sensitive applications significantly. While Forward Error Correction (FEC) is not new, the majority of the approaches consider FEC at the application layer. In this paper, we design and implement a framework within TCP with FEC that is application agnostic. We first show how such a design can provide benefits for high delay and lossy links. We further incorporate this design in MPTCP considering the fact that current TCP recovery mechanisms further escalate head-ofline (HoL) blocking in heterogeneous networks. We evaluate the performance of the proposed framework for latency-sensitive real application traffic such as video streaming with HTTP-DASH and H.264 and HTTP/2. We show that applying FEC on TCP level not only improves the application performance but also increases path utilisation.