Efficient 3D Positioning of UAVs and User Association Based on Hybrid PSO-K-Means Clustering Algorithm in Future Wireless Networks

Figure 8

(a) 3D UAVs trajectories for user-centric approach, (b) 2D UAVs trajectories for user-centric approach, (c) altitudes of UAVs for user-centric approach, (d) 3D UAVs trajectories for network-centric approach, (e) 2D UAVs trajectories for network-centric approach, and (f) altitudes of UAVs for network-centric approach.

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