Nowadays wireless communication is one of the most successful technologies thattransfers information via electromagnetic waves. Demand for wireless communication usage is growing continuously however the available electromagnetic spectral range is limited. One of the major solutions is to use of multiple antenna structure that a modern type of it, called massive MIMO, is under development in 5G. In this structure for increasing data rate and reliability of system, base station is equipped with large number of antennas. Increasing the number of antennas due to physical and complexity limitations is not always possible because it increases RF chains, costs, memory usage and computational complexity. In order to retain benefits of such a structure it is essential to implement all antenna elements and then select a subset of them with the best channel conditions, based on a logical criterion. In this thesis a massive MIMO system with spatial correlation between antennas in the base station is considered and based on antenna selection algorithms, a subset of antennas is selected. Then performance of the selected massive MIMO system is evaluated based on capacity and energy efficiency. Simulation results show considerable improvement in capacity and energy efficiency of system. On the other hand, up to now a closed form expression for energy efficiency of the massive MIMO system with spatial correlation and antenna selection has not been proposed; however, using wishart theorem we can provide a closed form expression for an uncorrelated channel case. In this thesis in order to provide an approximation for energy efficiency, we propose that spatially correlated selected channel matrix to be approximated by an i.i.d channel matrix with same dimensions but different variance. This approximation can be done by comparing eigenvalue distribution of correlated selected channel and uncorrelated channel. Then according to wishart theorem, matrix we can achieve a closed form expression for energy efficiency. Simulation results demonstrate an acceptable accuracy. Key Words : Massive MIMO system , Correlation , Antenna selection , Energy efficiency
