Evaluating the Utility of Media-Dependent FEC in VoIP Flows

In this paper, we present an analysis of the impact of using media–dependent Forward Error Correction (FEC) in VoIP flows over the Internet. This error correction mechanism consists of piggybacking a compressed copy of the contents of packet n in packet n + i (i being variable), so as to mitigate the effect of network losses on the quality of the conversation. To evaluate the impact of this technique on the perceived quality, we propose a simple network model, and study different scenarios to see how the increase in load produced by FEC affects the network state. We then use a pseudo–subjective quality evaluation tool that we have recently developed in order to assess the effects of FEC and the affected network conditions on the quality as perceived by the end–user.