Bewertung der perzeptuellen Qualität von VoIP in WLAN

Thomas Fichtel (2005): Bewertung der perzeptuellen Qualität von VoIP in WLAN Fachhochschule Salzburg: Diplomarbeit

Voice over IP (VoIP) is the technology of transmitting voice conversations over IP based networks. The voice data flows over a general-purpose packet-switched network, instead of traditional dedicated, circuit-switched voice transmission lines. VoIP today is one of those emerging services which are revolutionising telecom industries. The increasing dispersal of VoIP involves in a rising demand for the evaluation of networks. Regarding this point we focus on the specific demands of a network to provide defined levels of quality of service (QoS) for VoIP. For that reason this thesis discusses the impairments on the quality of VoIP transmissions and it gives an overview of the state-of-the-art procedures for determining the perceptual VoIP quality. Furthermore this work presents the adaptation and the implementation of a perceptual model, called the E-model. Another part and parcel of this thesis is the influence of wireless LAN (WLAN), especially in terms of handovers and QoS, on the perceptual quality of VoIP. In this context the handover procedures as well as the procedures to provide QoS via the wireless channel are described in detail. Finally measurement scenarios and results of VoIP transmissions via WLAN are presented and discussed.