1 Introduction
Cellular network operators have globally observed an explosive increase in the volume of data traffic in recent years. Cisco has reported that the volume of global cellular data traffic has tripled (year-over-year) for three years in a row, reaching up to 237 petabytes per month in 2010 [2]. This unprecedented increase in the volume of cellular data traffic is attributed to the increase in the subscriber base, improving network connection speeds, and improving hardware and software capabilities of modern smartphones. In contrast to the traditional wired networks, cellular network operators are faced with the constraint of limited radio frequency spectrum at their disposal. As the communication technologies evolve beyond 3G to long term evolution (LTE), the competition for the limited radio frequency spectrum is becoming even more intense. Therefore, cellular network operators increasingly focus on optimizing different aspects of the network by customized design and management to improve key performance indicators (KPIs).