long with the technology evolution, the UMTS terminal types and their capabilities are also changing quickly, and the portfolio of services that are offered by the network operators are expanding dramatically. All these aspects result in a drastic increase of the traffic volume, especially concerning the data traffic, and remarkable changes in the traffic pattern and characteristics in the current UMTS networks can be seen. Despite the great development of UMTS networks, network operators and vendors have struggled hard in the last years to gain profit. At the beginning they had to spend huge investments in both licenses and infrastructure for UMTS. But unfortunately the downturn of the economy throughout the past years has considerably influenced the revenue of 3G mobile X. Li, Radio Access Network Dimensioning for 3G UMTS, DOI 10.1007/978-3-8348-8111-3_1 Vieweg+Teubner Verlag | Springer Fachmedien Wiesbaden GmbH 2011 1 Introduction networks. As a consequence, it has been quite difficult for network operators to keep up revenue and until today they are still facing difficult times. In order for businesses to succeed in the current tense situation, network operators have to maximize their cost-efficiency in order to make maximum profit. An important lever for improving the cost-efficiency of UMTS networks is efficient design and use of the existing network infrastructure, in particular the radio access network, referred to as UMTS Terrestrial Radio Access Network (UTRAN). The radio access network is considered as one of the most important economic factors for the network dimensioning. As it has to cover large suburban and rural areas, the transport resource within the UTRAN is considerably costly. With the rapid expansion of the radio access network and the fast growing number of mobile users and traffic volume, the expenses on the transport link capacities and the cost of infrastructure will increase significantly. To achieve a cost-efficient design of the UMTS network, the radio access networks will have to be 