Access Point Selection Algorithm Based on Coevolution Particle Swarm in Cell-Free Massive MIMO Systems*

In this paper, we investigate the Access Point (AP) selec-tion problem in Cell-Free Massive multiple-input multiple-output (MIMO) system. Firstly, we add a connecting coefficient to the uplink data transmis-sion model. Then, the problem of AP selection is formulated as a discrete combinatorial optimization problem which can be dealt with by the parti-cle swarm algorithm. However, when the number of optimization variables is large, the search efficiency of the traditional particle swarm algorithm will be significantly reduced. Then, we propose an 'user-centric' cooper-ative coevolution scheme which includes the proposed probability-based particle evolution strategy and random-sampling-based particle evaluation mechanism to deal with the search efficiency problem. Simulation results show that proposed algorithm has better performance than other existing algorithms.