System Level Modeling and Optimization of the LTE Downlink

1. Motivation and Scope of Work1. Motivation and Scope of WorkInternet traffic has, since 1997, been more than doubling yearly, with an estimated1.3 exabyte 1 /month of Internet traffic as of Dec. 2012 [1]. As users increasinglyturn to mobile broadband, wireless cellular networks have been steadily evolvingfrom being voice-traffic-driven to the actual situation, where mobile traffic representsmore than four times that of voice traffic, as seen in Figure 1.1 (left). Although notgrowing at the same pace as overall traffic, mobile traffic is expected to grow tenfoldby 2017, compared to 2012 results [2]. Comparing the growth in mobile traffic tothe number of reported active sites, shown in Figure 1.1 (right) [3], it is clear thatmost of the growth has not been achieved by an increased number of sites but by acontinuous improvement of the standards in use.UL+DL monthly traffic (Petabytes)1,000Voice Data80060040020002007 2008 2009 2010 2011 2012Millions of Gigabytes in 6 months700600500400300200TrafficCell sites1002009 2010 2011 20121600140012001000800600400200Cell sites in service [thousands]Figure 1.1: Left: Global total traffic in mobile networks, 2007-2012 [2]. Right: Total Wirelessdata traffic and cell site count, Used with the permission of CTIA-The WirelessAssociation® [3].1 1 exabyte = 10 18 byte1