Jianguo Sun Wenshan Wang Sizhao Li Qingan Da Lei Chen 0029 Scheduling optimization for UAV communication coverage using virtual force-based PSO model. 1103-1112 2024 10 Digit. Commun. Networks 4 https://doi.org/10.1016/j.dcan.2023.01.007 db/journals/dcan/dcan10.html#SunWLDC24 streams/journals/dcan