Performance Evaluation of Quality of VoIP Service Over UMTS-UTRAN R99

Release99 of UMTS (universal mobile telecommunication system) network supports conversational services by means of UTRAN (universal terrestrial radio access network) dedicated transport channels (DCH). In this paper we evaluate by means of dynamic simulations the impacts of the radio access network on the end-to-end quality of service (QoS) of voice over IP (VoIP). In order to characterize the QoS level, an analytical model devoted to predict the mean opinion score (MOS) has been considered. Finally, an investigation of the most proper set-up of the service is also presented, taking into account inter-layer parameters such as the dimension of the VoIP client buffer as well as the block error rate at the air interface (BLER).