“Packet-E-Model”: E-Model for VoIP quality evaluation

Quality of service (QoS) for Voice over IP has to be measured by a perceptual QoS metric that corresponds to the intelligibility and clarity of the speech, as perceived by the listener. This subjective measure must be “captured”, mainly by models that rely on objective measurements, based on transmission delays and packet losses monitoring. These parameters which are common on such links can affect dramatically speech quality, especially when wireless links are considered. The ITU-T legacy E-Model, proposed to qualify audio and well adapted to circuit switched networks is not applicable to packet switched networks and must be adapted. In this paper, we present a new model to automatically quantify or measure the speech quality perception for voice/audio communications over IP, named here “Packet-E-Model”. We take into consideration synchronization issue, by implementing and testing two types of “offset” algorithms. We also consider a full duplex transmission scenario.