Methods and tools for the objective evaluation of voice over IP communications

In this paper we present the Netlab Quality Management Framework (NQMF), a set of tools especially designed to support controlled experimental analysis of voice-over IP (Internet Protocol) implementations. NQMF implements an integrated methodology to generate, in a controlled way, packet loss and delay sequences which effectively reproduce the fluctuating conditions of the Internet, and especially the high-frequency phenomena that mainly influence speech intelligibility. Our generator is based on a large set of measured sample traces, recorded in a variety of conditions over the network, and takes into special account the so-called 'coffee break' peaks. We also discuss a validation procedure that we carried out to account for the improvement that our generator has over simpler ones already proposed in the literature.