PSA Based Power Control for Cell-Free Massive MIMO under LoS/NLoS Channels
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A primary design goal of the cell-free (CF) massive MIMO architecture is to provide uniformly good coverage to all the user equipments (UEs) connected to the network. However, it has been found that this requirement may not be satisfied in case the channels between the access points (APs) and the UEs are mixed LoS/NLoS. In this paper, we try to address this issue via the use of appropriate power control in both the uplink and downlink of a CF massive MIMO system under mixed LoS/NLoS channels. We find that simplistic power control techniques, such as channel inversion-based power control perform sub-optimally as compared to max-min power control. As a consequence, we propose a particle swarm algorithm (PSA) based power control algorithm to optimize the performance of the system under study. We then use numerical simulations to evaluate the performance of the proposed PSA-based solution and show that it results in a significant improvement in the fairness of the underlying system while incurring a lower computational complexity.
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