The most important requirement in the future is
the provision of higher system capacity [5]. Over
the past few years, there has been significant
growth in the volume of mobile data traffic following
the proliferation of smartphones and new
mobile devices that support a wide range of
applications and services. Last year alone, the
volume of mobile data traffic grew 2.3 times,
with a nearly threefold increase in the average
smartphone usage rate [6]. There is now a general
consensus in the industry that such growth
will continue in the future as well. Many recent
forecasts project mobile data traffic to grow
beyond 24 times between 2010 and 2015, and
thus beyond 500 times in 10 years (2010–2020)
assuming the same pace of growth is maintained.