## 1 Introduction
Therefore, it is a need to design, develop, and implement architectural models to produce on-demand and edge-fog-cloud processing systems to continuously handle big data. The key problem with the ongoing development of mobile wireless systems is that it is thoroughly dependent upon network densifying to the cells or enhancing spectrum to attain the required throughput. The saturation point of these rare resources is almost reached. Moreover, cell densification and bandwidth increase also increases network latency and pay the cost of expensive hardware. Therefore, the throughput can effectively be increased by an untouched factor of SE without increasing cell densification and bandwidth to meet the current needs of wireless networks. Considering all these challenges, it also makes compulsory new means of channel capacity enhancements and SE techniques. Massive MIMO is an important part of the 5G key enabling technologies and is considered to be the solution to the above-discussed challenges. Figure 1: The prime objective of 5G. The data rate that can be communicated by a certain bandwidth in a particular communication network is referred to as SE, measured in bits/Sec/HZ. Spectrum efficiency, spectral efficiency, or bandwidth efficiency is a technical quantity described as the data rate that can be communicated over a specified bandwidth and used to measure a frequency band. It can be enhanced through increasing modulation order. We outline various capacity enhancements and SE improvement techniques in this research that will not only lead to enhanced network performance but also meets the ever-increasing user demands. We thoroughly discuss the benefits and current research challenges of using these technologies and presented subsequent contributions in this article. * A brief summary of the 5G and beyond 5G, is represented. * A significant review of key enabling technologies, in terms of enhancing channel capacity and spectral efficiency is described. * Massive MIMO (mMIMO): a perfect candidate for achieving high data rate, channel capacity, and energy efficiency. * Extensive description of the strengths and shortcomings of research efforts in implementing mMIMO. * Comprehensive analyses of these challenges and open research problems as well as state-of-the-art solutions including various figures and tables are presented. We also present previous 3 GPP wireless technologies standardization and the current deployment of 5G in the world. Moreover, we identify various research challenges and open research issues that need to be addressed in future mMIMO systems for 5G and B5G. Considering these challenges, this study will surely be helpful for the researchers working on mMIMO for 5G. The remaining article is categorized into various sections. In Section 2, the evolution of the 5G network summarizes, in Section 3 related work and SE improvement techniques have been discussed while in Section 4, we discuss the features, challenges, and benefits of key enabling techniques. Section 5 briefly describes a framework for supporting mMIMO technology and system-level performance features as a solution for the present challenges particularly to the enhancement of channel capacity and SE, with state-of-the-art proposed solutions. Finally, the article is concluded in Section 6.