Massive-MIMO- Past, Present and Future: A Review

Objectives: Multiple Input-Multiple Output (MIMO) systems have turn out to be necessity of wireless communication systems to conquer bandwidth restrictions. Massive-MIMO systems are capable of improving the channel capability of the system. This paper presents review on design, architecture, challenges, limitations and the possible improvements in a Massive-MIMO system. Methods/statistical Analysis: Comprehensive study has been performed to build up substantial understanding about various designs, architectures and techniques described so far by enthusiastic research scholars regarding system model and practical implementation of the Massive-MIMO systems. The review is paying attention on the problems like, getting true channel state information, antenna correlation, channel estimation, signal detection schemes at receiver end, different kind of possible network architectures and their complexity and hardware impairments. Brief information is added about the projects running worldwide on Massive-MIMO and its application in future communication systems of next generation. Findings: It is observed that multiple antenna systems with huge amount of antenna elements at base station are competent to increase data rate by many folds, without requirement of any extra bandwidth, as compared to other existing technologies. Massive-MIMO combined with multiple carrier systems (Massive-MIMO-OFDM) followed by suitable signal detection schemes, like beam forming, gives overwhelming results. Application: With possibilities of further research and continuous improvements, Massive-MIMO system is one of the best suitable choices, among various technologies, for next generation wireless communication systems, like 5G.