dimensioned appropriately for the types of services which are to be offered. Excessive over-dimensioning will waste the expensive bandwidth resources unnecessarily, whereas under-dimensioning can lead to a less satisfactory quality of service perceived by the mobile users. A properly dimensioned UMTS radio access network can result in significant reductions in capital expenditure required for a desired target quality. 1.2 Scope of UMTS Network Dimensioning In this thesis the scope of UMTS network dimensioning is focused on the radio access network, as an efficient design of the radio access network is the key process to guarantee the optimal use of the network resources and achieve the best cost-efficiency of a UMTS network. The specific task of dimensioning is to determine appropriate bandwidths for the transport links within the radio access network, with the objective of maximizing utilization of the allocated transport resources while ensuring the QoS requirements of the UMTS network and the end-users. Figure 1.1 illustrates a generic view of a UMTS network, which presents a hierarchical network structure. The core network is the highest level of the hierarchy, which is the backbone of the UMTS network providing the gateways and connections to the external networks. The mobile users (UEs) are the lowest level of this hierarchy. They are connected through the base station (Node B) to the radio access network, i.e. UTRAN. In the radio access network, groups of Node Bs are connected to one Radio Network Controller (RNC) via switches or routers. From there, the traffic from different Node Bs are aggregated and routed to the RNC. 1.2 Scope of UMTS Network Dimensioning Switches or routers Core network nodes Network 1ub Interface Node B Node B Node B Figure 1.1: Generic view of a UMTS network Typically, a large UMTS radio access network consists of a number of RNCs each controlling hundreds of Node Bs. Such a large radio access network often involves considerable network costs, as the required transport resources an