The Design And Implementation Of UAV Uplink Communication Based On Single-carrier Frequency Domain Equalization

With the development of unmanned aerial vehicles(UAV)technology,UAV have been used more and more widely in military and civilian fields.With no doubt,the communication link system is the most important part of the UAV,and it's the guarantee for UAV to work normally.Typically,the multipath interference and fading in complex wireless channels will greatly reduce the reliability of communication.In order to the accurate and efficient communication of the UAV,it's essential to apply effective antimultipath technology.Currently,there two popular methods to combat multipath effects,called orthogonal frequency division multiplexing(OFDM)technology and singlecarrier frequency domain equalization(SC-FDE)technology.An UAV uplink communication based on SC-FDE is designed and implemented in this thesis because compared to the OFDM technology,SC-FDE doesn't have the disadvantages of high peak-to-average ratio and high sensitivity to frequency offset.In this thesis,the development history of UAV,the channel features of the UAV communication,the technology characteristics of SC-FDE and the important technologies of the SC-FDE systems are introduced.On the basis of fully understanding the theory of the SC-FDE communication system,following work has done in this thesis.1.An UAV uplink communication based on SC-FDE was designed and implemented by using Matlab.The key algorithms in the SC-FDE system were simulated,compared,optimized,and the optimal algorithm was selected.The contents of design and simulation mainly include channel coding and decoding,data modulation and demodulation,frame structure design of the system,shaping filtering,timing synchronization and carrier synchronization algorithms,channel estimation and equalization algorithms,and the like.2.An UAV uplink communication based on SC-FDE was completed by using FPGA.This communication link was designed using Verilog hardware language design.The design mainly includes the realization of signal processing modules in sender and receiver of SC-FDE system,and the realization of the Digital up-conversion and DA/AD module.3.The feasibility of the system was verified by building a SC-FDE communication system hardware platform.The hardware platform components are as follows:Two pieces of K7-FPGA chips that have been processed by the baseband module,a processing board integrated with an Analog Device AD9957 DA conversion chip and another processing board integrated with a Linear Technology LTC2185 AD conversion chip.Using the built hardware platform,the system test of the UAV uplink communication was completed and the feasibility of all modules was verified.By testing the sending and receiving functions of the medium frequency module and the BER of the system which was implemented by FPGA in the white noise channel and multipath channel with different SNRs.Comparing with results in simulation with Matlab,it is proved that the SC-FDE communication link can communicate normally,The test result indicated that this communication link can work normally.And in a certain extent,this system can overcome noise,and multipath effect.Therefore,this thesis has realistic meaning.