AN. From Release 5 onward, IP transport is introduced as an alternative transport technology to replace ATM in the UTRAN to provide improved cost efficiency of the transport network. Migrating from ATM to IP transport requires some change of the deployed QoS schemes as well as traffic- and resource control functions in the transport network, which result in different transport efficiency. In addition, when combing Re199 traffic with high speed radio access traffic over the ATM transport on the lub interface, service prioritization and path separation are applied to give higher priority for Re199 traffic and at the same time to enhance the transport efficiency by improving the multiplexing gain on the links. The dimensioning results demonstrate the improved cost efficiency of applying these transport solutions. QoS Mechanisms In the transport network, various QoS mechanisms can be applied to provide distinguished service treatment and control the usage of resources in order to guarantee the desired level of QoS for a variety of services. Resource reservation and admission control: the UTRAN transport network has to guarantee strict delay requirements and moreover its transport resources are limited. Therefore reservation of the transport resource for different flows and controlling the usage of the resources in the UTRAN are important [NRM*05]. 1 Introduction Strict Priority: traffic is served in the order of its priority. Lower priority traffic can be served only when the higher priority traffic has been served. Usually Rel99 traffic has higher priority than the high speed radio access traffic. This is usually realized on the packet level in both ATM and IP transport networks. Differentiated Services (DiffServ): DiffServ is an IP-based QoS framework. It provides different treatment of flows or aggregates flows by mapping multiple flows into a finite set of service levels. In this thesis, a DiffServ-based QoS architecture is used in the IP-based transport of the radio access network (see Chapter 3). The applied pa