Research On Data Collection:UAV Trajectory Desiging And NOMA Transmission Scheduling

In recent years,with the development of advanced technologies,the Internet of Things(IoT)has attracted wide attention in the fields of energy,medicine and agriculture.As a necessary function of IoT and the foundation of its application,data collection has become a hot research topic.To compensate for traditional data collection methods which have limited network transmission performance,researchers have introduced Unmanned Aerial Vehicle(UAV)communication technology into IoT.At the same time,due to the exponential growth of IoT devices in the 5G era,non-orthogonal Multiple Access(NOMA)technologies have been introduced into IoT to improve spectrum efficiency and meet its large-scale access requirements.Therefore,UAV communication technology and NOMA improve the performance of communication system in data collection scenarios from two dimensions of transmission performance and spectrum efficiency respectively,which has very important research value.At present,the research on UAV trajectory designing and NOMA transmission scheduling in the scenario of IoT data collection is very limited,and there are the following shortcomings:(1)For active device scenarios,improving the survival time of IoT has not been considered;(2)For passive device scenarios,UAV trajectory designing has not been well studied;(3)The application of NOMA grouping scheduling is relatively simple.In view of these problems,this paper mainly includes the following two aspects:(1)In view of the short life time of IoT in the active device scenarios,this paper proposes a method to charge IoT devices by using UAV while collecting data.This paper maximizes the residual energy of devices through the joint optimization of UAV trajectory,time scheduling,power allocation of devices and NOMA grouping scheduling,and proposes a heuristic NOMA grouping scheduling.Simulation results prove that the proposed algorithm can effectively improve the residual energy of devices,thus prolonging the survival time of IoT.(2)In view of the problem of low communication rate of IoT devices in passive device scenarios,this paper use UAV to carry the radio frequency transmitter and receiver for data collection.By jointly optimizing UAV trajectory,the reflection coefficient of Backscatters and NOMA grouping scheduling,the achievable rate of Backscatters is maximized.A heuristic NOMA grouping strategy is proposed in this paper,and the simulation results show that the proposed algorithm can improve the achievable rate of Backscatters.