A Survey on Energy Optimization Techniques in UAV-Based Cellular Networks: From Conventional to Machine Learning Approaches. - Attai Ibrahim Abubakar; Iftikhar Ahmad; Kenechi G. Omeke; Metin Öztürk; Cihat Öztürk; Ali Makine Abdel-Salam; Michael S. Mollel; Qammer H. Abbasi; Sajjad Hussain; Muhammad Ali Imran 001 (CoRR, 2022)