  In this article, one first introduces the general landscape of the next
generation of wireless communication systems (5G), including its drivers and
requirements, and the candidate technologies that might help achieve its
intended goals. The following areas, which the author considers to be of
particular relevance for 5G, are then introduced: detection and access of free
spectrum over bands of an heterogeneous nature, extreme densification of
networks (massive base station deployments), extreme increase in the number of
antennas in transmitter arrays and their interaction with a novel waveform,
integration of both wireless and optical sides of telecom networks, and study
of wireless networks using the magnifying glass provided by complex systems
science. In particular, recent results from the author's research team are
shortly discussed for each of these research areas.
