ated Services [BCS94] and the Differentiated Services [BBC*98] frameworks. It is clear that QoS aspects, i.e. the various frameworks for QoS as well as the enabling technologies, need to be considered for network dimensioning. They determine the constraints 1.4 Contributions of this Thesis and the objective of the relevant dimensioning procedures. As soon as QoS requirements are defined, the networks need to be dimensioned appropriately to meet the requirements. 1.4 Contributions of this Thesis In this thesis dimensioning is investigated for the UMTS radio access network with specific focus on the transport network of the lub interface, which is connecting the Node B with the RNC. The main contribution of this thesis is an elaborate analysis of the important aspects that have significant influence on dimensioning the lub interface and evaluating their particular impacts; and secondly developing novel analytical methods to accurately calculate the required transport capacity for the lub interface for the maximum utilization of the transport resources. In order to give a comprehensive investigation of the dimensioning of the lub interface, different traffic scenarios, evolutions of UMTS radio access networks, transport solutions, QoS mechanisms and network topologies are investigated. For performance analysis and evaluations, as well as for validating the developed analytical dimensioning models, several dedicated simulation models were developed to model different UMTS radio access networks, including modeling of their specific protocol structures, channels, radio functions, and transport technologies (see Chapter 5). By performing extensive simulations and analysis of the simulation results, important dimensioning rules are derived and the proposed analytical dimensioning models are demonstrated. At the end, to summarize the proposed analytical dimensioning approaches in this work, a dimensioning tool is implemented including all the proposed analytical models. The developed dimensioning tool can perform dimensio