posed analytical models are based on queuing models, which are focused on the packet level taking the aggregated traffic into account. The proposed queuing models define an appropriate arrival process to capture the important characteristics of the aggregated traffic on the link, and an accurate server process considering the packet length distribution and the given link capacity. In the mixed traffic scenario, packet scheduling is considered in the queuing models, taking 1.4 Contributions of this Thesis into consideration the potential multiplexing gain. An overview of analytical models used for dimensioning is given in Chapter 4. UMTS Radio Access Network Evolutions Within this thesis a number of evolutions of UMTS radio access networks are investigated for dimensioning: UMTS Rel99 as the basic UMTS network and HSDPA/HSUPA which are the high speed radio access technologies. For each evolution of the UMTS radio access network, its specific protocol stacks and important features are studied, especially on the lub interface. Their particular traffic- and resource control functions are carefully considered for dimensioning the lub transport network, as they will cause significant impact on the usage of the transport resources. Examples for traffic control functions are congestion control and flow control algorithms (for HSPA), packet scheduling, buffering and shaping. Examples for resource control functions are the Connection Admission Control (CAC) and the Bit Rate Adaptation (BRA) algorithm (see Chapter 3 for a detailed introduction). Furthermore, various traffic scenarios and network structures are investigated for dimensioning of the lub interface for each radio access network evolution. Transport Solutions Transport solutions have great impact on the utilization of the transport resource. In this thesis, two fundamental transport technologies used in the UTRAN are investigated: ATM and IP. ATM is the transport technology used in UMTS Release 99 and Release 4 to transfer user data and control traffic in the UTR