The universalmobiletelecommunications system (UMTS) is a technical standard for a third generation (3G) telecommunication system. UMTS provides data rates more than three 1 times higher than its second generation (2G) predecessors. The increased speed enÂ- ables, for example, video calls, music downloads, or fast web surfing. The technology is already widely available. In 2007, a total of 166 commercial UMTS radio networks are operational in 66 countries covering all continents (UMTS Forum, 20°7), and there are already more than 100 million UMTS subscribers (3GToday. com, 2007; UMTS Forum, 2006). The market for mobile telecommunication is, however, increasingly competiÂ- tive, therefore operators need to invest effectively. In Western Europe, mobile phone penetration has reached 100 % in 2006 and the average revenue per customer is deÂ- clining (3G. co. uk, 2007). Besides spectrum license fees, the main cost driver is network infrastructure (Ellingeret al. , 2002). Radio network planning can cut operational and capital expenditure by up to 30 % (Dehghan, 2005). Good radio network planning is difficult for UMTS, because its radio interface is more complex than anything used at mass-market level before (Dehghan, 2005). ConÂ- nections are separated via codes; they share the same frequency band and are thus subject to interference. On each link, the system constantly regulates the amount of generated interference to a minimum via a power-control feedback loop.
