Leader–Follower UAV-Assisted WSNs for Improving Data Collection Rate and Shortening Flight Time

In unmanned aerial vehicle (UAV)-assisted wireless sensor networks (WSNs), most schemes use a single UAV to collect one regional sensors’ data or multi-UAVs independently work in multiregions for time-sensitive fixed-ground-trajectory scenarios. To the best of our knowledge, they are a single-objective performance enhancement scheme, such as improving data collection rate or shortening flight time. Moreover, these two objectives are contradictory. To address this problem, we propose leader–follower UAV data collection algorithm (LFUDC) that is a joint framework with trajectory adjustment and air-to-ground (A2G) cooperation. LFUDC could simultaneously improve data collection rate and shorten flight time. There is little research about double-objective performance enhancement schemes like LFUDC, as far as we know. Through air-to-air (A2A) communication link, leader UAV controls follower UAV trajectory adjustment. Therefore, the flight formation of leader–follower UAVs could build a new shape of covered communication area on the ground. Unlike present work, the overlapped area makes their sensors have at most two times to transmit data. Besides, leader–follower UAVs realize priority grouping of sensors according to connection time and use centralized control methods to make sensors in one priority group send data according to their command. This effectively avoids data collisions. Generally, the priority group and centralized control methods are different from most existing research. LFUDC outperforms single and double UAV data collection algorithms, which is robust for changing the horizontal minimum speed of leader–follower UAVs. Through LFUDC, we find a new technological roadmap for our future multiobjective performance enhancement. However, the limitation of LFUDC is the high cost of leader–follower UAVs.