Trajectory and Resource Allocation Optimization for Unmanned Aerial Vehicles Assisted Communications in Unlicensed Bands
To solve the bottleneck problem of constrained spectrum resource for Unmanned Aerial Vehicles(UAVs)in unlicensed bands,a co-optimization scheme high spectral efficiency in underlay mechanism is proposed for UAV-assisted monitoring communication networks in urban environment.Considering the high maneuverability of UAVs,the air-to-ground channel is modeled as a probabilistic Line-of-Sight(LoS)channel,and the co-channel interference and maximum speed constraints are adopted to formulate a hybrid resource optimization model for power allocation and trajectory planning,enabling UAVs to construct the fast transmission scheme for monitoring data with occupied spectrum within the given time.The original problem is an NP-hard and non-convex integer problem,which is first decomposed into a two-layer programming problem,and then solved by applying the slack variable and Successive Convex Approximation(SCA)technologies to transform the trajectory design problem into a convex programming problem.Compared with the Particle Swarm Optimization(PSO)algorithm,the proposed joint optimization scheme is verified to improve the spectral efficiency by up to about 19%in simulations.For high-dimensional trajectory planning problems,the SCA-based algorithm is proved to have lower complexity and faster convergence.