Abstract
This paper solved a propulsion power minimization problem subject to a total data-bits constraint of an unmanned aerial vehicle (UAV) enabled full-duplex mobile relaying system, where a full-duplex UAV relay is dispatched as a mobile relay to assist data transfer from a source to a destination by using three trajectory flying modes, namely, the UAV first flies in a circle above the source, next flies to the destination in a straight line, and finally flies in a circle above the destination until all the data bits has been transferred. Since the propulsion power minimization problem is a non-convex mixed integer programming problem and its closed-form solution is hard to obtain, it is transformed to three sub-problems so as to simplify its solution. After solving the three sub-problems, an iterative algorithm is proposed to achieve a sub-optimal solution to the propulsion power minimization problem, leading to a new hybrid circular/straight trajectory (HCST) design. Computer simulations are conducted and the results validated the proposed HCST design. It is shown that compared to the straight or circular flight trajectory design, the HCST performs well in terms of energy saving for the long distance and big data communication cases.