If 2011 was the year of the heterogeneous network (HetNet) concept, Mobile World Congress 2012 in Barcelona was characterized by the emergence of “small cells” as a solution to help operators optimize their network architecture and face the rapidly growing demand for coverage and capacity: currently there are close to 5.3 billion mobile subscribers texting, talking and downloading. By 2015, mobile subscriptions are expected to reach 6.4 billion and mobile data will exceed 30 times that of current levels.

Reducing distance between the user and the base station and reducing the number of instantaneous users seeks to improve the signal quality and allow a higher data rate in both up and down links. The names “femto,” “pico” and “micro” are now complementary to the well-known “macrocell” terminology and define a wide range of options for network deployment. They have been considered recently by the standardization