In this chapter we discuss the general techniques of multi-antenna systems. Then, we delve to describe four recent trends in interference mitigation technologies that will change the design of the future 4G and beyond (5G) of mobile and wireless communication systems. Particularly, we consider the coordinated multi-point MIMO systems, smart terminal devices techniques, millimeter-wave communications and massive MIMO systems. We discuss the fundamental concepts of those new approaches, along with their advantages, and the challenges facing such technologies. Even though the references list of this chapter is not anticipated to be exhaustive, the cited articles and also the references therein should be good sources of further reading to start with.
Multi-User Massive MIMO Systems Based on Hybrid Analog-Digital Beamforming for Millimeter-wave Communications