Enhancement of spectral and energy efficiency in massive MIMO systems with linear schemes

Massive-Multi Input and Multi Output (MIMO) antenna system is considered as the key technology to improve both spectral efficiency (SE) and energy efficiency (EE) for 5G systems. Where pilot contamination and inter-cell interference have been considered as basic limiting factors to achieve high data rate. These parameters will saturate the SE and truncate to a constant value. In this work, we explore the effective evaluation of SE and EE of the M-MIMO antenna system with optimal users. In this work, we basically considered linear processing algorithms such as zero-forcing (ZF), maximum ratio combing (MRC) and minimum mean square error (MMSE) for the analysis SE for the both single and multi-cell scenario in M-MIMO systems. In this paper, we provide a platform to improve the SE and EE with a variation of base station (BS) antennas M and pilot reuse factor λ. We also derived the explicit and exact expressions for the analysis of SE and EE with perfect and imperfect channel state information (CSI). Which are very tight and tractable approximations in the prospective of realistic system scenario. We mainly focused on the asymptotic limit of SE and also obtain optimal user terminals K. It has been noticed that the SE performance greatly depends on the receiving combined scheme. We compared the simulation results for SE based the parameters such as varying antennas at the BS M, optimal UTs K and finally pilot reuse factors λ=4 and λ=7. Here, the simulation results of the BS antennas per-user (M/K) and optimal users K, highly depend on the receive technique and the BS antennas M. We also demonstrated the simulation results with the variation of per-user SE versus the BS antennas. The simulation results were performed by using Matlab 2015b.