ioning. The following paragraphs present the most important challenges, which are expected to significantly influence the dimensioning of a UMTS network, and point out their implications for network dimensioning. Evolution of UMTS With the fast development of UMTS in the past few years, evolved cell phones and smart- phones already support a broad range of data services, including video streaming, typical Internet applications like e-mail, file download, web browsing etc. In 2004, 3G UMTS interface cards for laptops or mobile computers were launched in the market, often coupled with volume based or flat-rate connectivity contracts, and met a considerable market success. In 2008 the iPhone 3G was released and it represents a new trend of UMTS terminals. It not only provides 3G data speeds and offers a wide range of Internet services, but also offers functionality of mobile music (music on the move) that borrows from "the iPod" experience. With these evolved UMTS terminals, the range of the delivered services in UMTS has rapidly expanded from voice-centric to a variety of appealing data services, and the volume of traffic generated by UMTS terminals and directed to the Internet has registered a rapid increase. The growing popularity of UMTS terminals and services has notably extended the coverage of Internet access, and the UMTS networks are now becoming key components of the Internet in Europe. In addition to great improvements on UMTS terminals, the UMTS radio access technology is as well under evolution. After the operation of UMTS Release 99 (Re199), which is the first UMTS release, High Speed Packet Access (HSPA) was introduced as a major step along the path of technology evolution of UMTS. It was launched in two phases, the first offering improvements in the downlink (HSDPA), while in the second phase the uplink offers enhanced performance (HSUPA). The launch of HSPA brought a major development in improving the end-user experience with the superior throughput and latency. In addition, operators will benefit f