2.2.6 On-Board Energy
Another major factor having a crucial impact on the performance of UAV assisted wireless communication networks is the limited available UAV on-board energy. This in turn limits the UAV flight and hovering duration. Over a period of time, research work has been carried out as in Refs. [63–74], where various methods have been proposed for minimizing the energy usage of UAVs in UAV communication. Few solutions proposed to encounter this challenge can be listed as, UAV optimal trajectory determining, efficient scheduling in multiple UAV scenario, dynamically activating only the required number of drones at a particular time, optimization of transmission times, reducing the required transmit power, efficient resource allocation schemes, energy harvesting for operations of small UAVs and many more. Managing the available resources of energy, bandwidth and time plays a crucial role in improving the performance of UAV communication systems [70, 75].
2.3 Conclusion
UAV aided wireless communication networks is yet another important step towards the development of future smart cities of 5G-IoT era. For the past 4 decades UAVs have been occupying the sky and playing a vital role in wireless communication systems. Researchers across the globe have identified various challenges of this technology and have proposed feasible solutions to these problems. Efforts have been made here to highlight few of the challenges to be overcome while designing the optimum UAV-assisted networks, thereby paving a path for the budding researchers to tread upon. Over the past few years many research challenges have been identified and worked upon and this technology is being updated at a tremendous speed. The progress is still ongoing.
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