Cellular technologies: A journey towards 5G

5G is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backward compatibility. However, unlike the previous four generations, it will also be highly integrative providing universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach new levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. In this paper the key challenges for future research and 5G standardization activities are discussed, providing overview of the current literature.