In view of the rapid increase in demand for mobile data services, next generation wireless communication systems will have to provide greatly increased capacity density and high data rates greater than 50Gbps. However, satisfying these requirements for increasing numbers of users and connected devices, and increasingly bandwidth, processing power and energy-hungry applications will require a transformation in the way in which current mobile and wireless networks perform.Recently, massive multiple input multiple output (MIMO) technology, where each base station (BS) is equipped with a large number of antenna elements (typically tens or even hundreds) has emerged as a key enabler to achieve a 1000 times data rate and enormous spectral and energy efficiency. In order for massive MIMO to become a reality, the proposed work aims to explore transformative methods for the design of innovative techniques in 3 key challenging areas of massive MIMO communication systems: (i) fundamental limits; (ii), (ii) transmission strategy; and (iii) caching mechanisms. The solution is achieved with small remote antenna units equipped with compact massive MIMO arrays deployed over certain coverage regions, and developing practical signalling schemes, network coordination, and management protocols.