Interference Mitigation in MIMO Systems with Imperfect CSI using Beamforming based Precoding Algorithm

Abstract

Multiple Input Multiple Output (MIMO) communications is one of the main researched technologies in 5G. It is very promising as it can provide spatial diversity. The main obstacle facing using MIMO technology is the interference problem especially that one resulting from pilot contamination which affects channel estimation processes. This interference appears when the cell users sends uplink nonorthogonal pilot sequences to their corresponding base stations. Pilot Contamination affects the efficient use of the spectrum and leading to a decrease in the data rate and the reliability of the system. In this paper a precoding algorithm based on random beamforming technique is proposed to solve the problem of pilot contamination. The precoding algorithm achieves a high power subspace for the desired signal and nulling other Interference-Plus-Noise signals even in cases of pilot contamination. The beamforming algorithm aims at dividing the space into unit orthogonal beams to select the highest quality beam for a certain user. Combining both techniques achieves interference mitigation by aligning the desired signal in the subspace with the highest power while ensuring the selection of the highest quality channel for transmission.