Optimal pilot reuse factor based on user environments in 5G Massive MIMO

Massive MIMO is designed to improve capacity and performance of the network by using hundreds or even thousands of antenna and terminals attached to the base station. However, the fundamental limitation of this technology is pilot contamination problem during uplink which limits throughput. Pilot contamination problem can be solved by using pilot reuse factor value higher than one and to get maximum area throughput in the system, this factor must be switched dynamically according to the environment and number of active users. As of now increasing either bandwidth or cell density has been considered but the other factor increasing area throughput, i.e., spectral efficiency has been untouched. In this paper, we find the optimal values of pilot reuse factor to always run the system at maximum spectral efficiency to get higher area throughput. The experiment was simulated in six different environments with the variable number of active users in the cell and results through MATLAB simulations show that with appropriate use of the value of pilot reuse factor based on environment and number of active users, we can always run the system with maximal spectral efficiency and achieve higher area throughput.