Research On Spectrum Sharing And Multiple Access Technology Of UAV Network

Since unmanned aerial vehicles(UAVs)have the advantages of flexibility,low cost and high-maneuverability,UAVs are widely used in many fields.One of the important applications is disaster relief.Serving as a base station,UAV provides communication services for ground users.Compared with a single UAV,multiple UAVs form an air adhoc network,which can provide more cost-effective communication services for massive ground users.Since UAVs need to forward data from ground users and return their own perception data,a large amount of data transmission is required.Spectrum resources are relatively tight.How to obtain more spectrum and how to use spectrum resources efficiently are the two main problems to be solved in this thesis.Based on the ground wireless network assisted by UAVs,this thesis studies the spectrum sharing,and designs a multiple access scheme for UAV network.The research contents are as follows:1)Aiming at the coexistence of the ground wireless network and the unmanned aerial vehicle(UAV)network,the access strategy of the UAV in the frequency band of the ground wireless network is studied.Considering the missed detection probability,interruption probability of ground wireless network,and false alarm probability constraint of UAV network,we derived the UAVs height values under different access strategies and determined the optimal sensing time of the UAVs under time domain access.Simulation proves the rationality of theoretical analysis.The simulation results firstly obtained the numerical solution of the height boundary,and verified the performance of the ground wireless network and the UAV.The simulation results also obtain the throughput and optimal spectrum sensing time under the time domain access strategy.2)After the UAVs obtain the unlicensed spectrum of the ground wireless network,combined with the authorized spectrum of the UAV network,the multiple access protocol of the UAV network is studied.Considering the characteristics of large-scale deployment,large number,and high mobility of UAV network,the channels are divided and a multiple access protocol based on time division multiple access(TDMA)reservation is designed.The protocol performance indicators are analyzed,such as throughput and delay.In addition,a theoretical analysis of the dynamic frame length setting of the application period is provided.Simulation results prove that in this scenario,the proposed TDMA reservation-based multiple access protocol is superior to the Carrier Sense Multiple Access with Collision Avoidance(CSMA/CA)protocol in throughput and latency.