Convergence Analysis of Massive MIMO Antenna Arrays Using a Geometry-Based Stochastic Channel Model

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In order to reap the full benefits of massive MIMO, the Base Station (BS) anten￾nas must be significantly large to converge to favorable propagation condition or attain convergence (the state where the effect of noise and fast fading vanishes). However, increasing BS antennas results in closely spaced antenna elements which inadvertently leads to the detrimental effects of Spatial Correlation (SC) and that can affect the convergence of Massive MIMO System. So far, research works on Convergence have been investigated using Correlation-based Stochastic (CBSCM) channel models, which does not reflect accurate massive MIMO channel. This channel model does not take into consideration channel parameters such as the Pathloss, power delay profile as well as the characteristics of the antenna ar￾ray needed for the practical massive MIMO system implementation. Therefore analysis of massive MIMO convergence regarding the Geometry-Based Stochastic Channel model (GBSCM), which reflects real practical massive MIMO channel and the effects of SC is needed. In this thesis, the convergence of massive MIMO based on GBSCM is studied. The effect of 3D SC of uniform rectangular and cylindrical array (URA and CA) based on the Maximum Power of Arrival (MPA) is incorporated. In the analysis, the Diagonal Dominance and Mean Absolute Deviation convergence metrics, were considered to study the effects of the SC on the asymptotic behavior of the channel matrix. The results support exist￾ing development that, increase in azimuth and elevation spreads of the angular distributions of arrival and antenna element spacing reduces the SC and thereby increases convergence rate of massive MIMO. Results also show poor performance for the Laplacian and Von Misses distributions in GBSCM, even for higher AS and ES, and angular spreads. Further it was realized that, in GBSCM, the con￾vergence of massive MIMO was sensitive to antenna array topology regarding Gaussian and Student’s t-distributions. This contradicts previously established results that convergence is insensitive to antenna topology in CBSCM.
A Thesis submitted to the Department of Telecommunications Engineering College of Engineering in partial fulfillment of the requirements for the degree of MPHIL. TELECOMMUNICATIONS ENGINEERING