Spectrum Resource Utilization And Optimization For UAV Communication

In recent years,due to the rapid development of broadband large-capacity information transmission,personal communication and military security/anti-interference communication,the demand for information transmission systems assisted by unmanned aerial vehicles(UAVs)in modern wireless communication is also explosive.At the same time,by observing statistics on R&D investment in UAV communication at home and abroad,it can be clearly found that the UAV spectrum resource optimization field has become an extremely active field for the research,development and utilization of international electromagnetic wave spectrum resources.It can be seen that the current research on the utilization and optimization of spectrum resources in the UAV communication system and its efficient transmission theory are important.In view of the particularity of UAV communication scenarios,this paper first considers the space-ground channel model based on free space loss.Under the current situation of severe shortage of spectrum resources,modelling and analysis according to different application scenarios,and then using advanced convex optimization.Convex Optimization theoretical tools to carry out research on the efficient transmission mechanism of UAV communication systems.The research points include the following three aspects:(1)Design of UAV simultaneous wireless information and power transfer(SWIPT)system based on maximizing energy harvesting: This paper studies a single-user power splitting-based multiple-input multiple-output system for simultaneous wireless information and power transfer.We aim to maximize the harvested power by joint design of transmit signal covariance matrix and receive power splitting factor under both a system rate constraint and a total power constraint.The harvested power maximization problem is difficult to solve due mainly to the non-concave objective and the nonlinear coupling of design variables in the constraints.To tackle these challenges,we first derive a good approximation of the problem by ignoring some negligible noise terms and then further simplify it to a more tractable form by well exploiting the problem structure.Based on the Frank–Wolfe algorithm,we propose a simple yet efficient iterative algorithm to address the resulting problem.Numerical results validate the efficiency of the proposed algorithm.(2)Design of UAV proactive control system based on maximization of control signal QOS: In the research of spectrum resource access and optimization based on UAV remote channel,designing an efficient iterative algorithm and finally providing a ground control station with a reasonable spectrum efficiency for multi-UAV spectrum resource allocation is the focus of this study.In order to improve the quality of the control signals(QOS)of each control signal as much as possible,this study sets the performance index so that the SINR values of all the UAVs receiving the control signals are as large as possible.Therefore,the frequency decision problem of the UAV remote control channel will adopt the Max-Min fairness index as the optimization target of the problem;Then by introducing the spectrum resource allocation matrix,the original NP-hard problem is transformed into a simple and clear problem of easy solution optimization.Design and propose two new,efficient and theoretically guaranteed methods for accessing and optimizing the spectrum resources of UAVs.At the same time,this research point innovatively considers the problem of UAV communication decision-making,which is represented by some drones occupy a specific channel for special reasons;(3)Design of UAV uplink transmission system based on maximizing transmission rate: In the UAV uplink transmission system,after the observation data is obtained,the UAV group transmits the observation data to the base station through the uplink.Due to the large amount of data transmitted,the drone requires a higher transmission rate in the link.In this study,based on the complex frequency optimization problem of UAV telemetry channel,Orthogonal Frequency Division Multiplexing(OFDM)is used to perform multi-carrier modulation on the observation data to realize high-speed data transmission.However,in practice,since the total number of subcarriers is often limited,it is possible for different drones to share a certain subcarrier and cause co-channel interference.In order to solve the above problems,this study uses the Signal to Interference plus Noise Ratio(SINR)of the received signal as a metric to reduce the number of subcarriers shared by the drone and reduce the number of other drones to the target.The interference of the machine,so as to achieve the maximum transmission rate of the drone group information.