An Implementation Of Shared Signal In OFDM Radar And Communication

As two different systems,radar systems focus on accurate tracking and detection of targets,and communication systems are dedicated to the reliable and effective information transmission.These two systems are widely used in both civilian and military fields and have broad prospects for development.However,with the continuous evolution of modern combat systems and increasing number of radio equipments,many problems have arisen,such as the scarcity of spectrum resources,the redundancy of equipments,and the interferences among various systems.At the same time,with the development of digital signal processing and software radio techniques,the differences between radar systems and communication systems are decreasing,providing a basis for the fusion of radar and communications(Rad Com).Designing a shared signal,which can simultaneously perform wireless communication and radar detection,is an efficient method in Rad Com system design.Shared signal based Rad Com system design possesses many advantages,such as making full use of spectrum resources,reducing interferences among signals,and saving space for platforms,which becomes one of the hot research topics.Therefore,this dissertation mainly studies the implementation of Rad Com system design based on orthogonal frequency division multiplexing(OFDM)shared signal through related hardware and software radio equipment.Firstly,the basic principles of radar system and communication system are introduced,and the differences between these two systems are analyzed.Afterwards,the feasibility of the fusion of radar and communication systems is illustrated after the system model design and formulas derivation.Moreover,several related performance metrics are shown,such as peakto-average power ratio,ambiguity function,intercept factor,and bit error rate,providing guide for optimizing the detection performance and communication performance in the subsequent design.Next,the basic theory of OFDM signal is introduced,as well as its time-frequency domain structure and the modulation and demodulation method of the OFDM signal.What's more,the working process is illustrated via flow chart.After that,the radar ambiguity function and constellation of the OFDM shared signal are analyzed from analytical and numerical aspects.In addition,solutions are proposed and verified for the synchronization problems encountered in actual system design.Lastly,experiments and test schemes has been carried out.A hardware test platform has been built by the Universal Software Radio Peripheral Reconfig I/O(USRP RIO)software radio devices and related software,and utilized to test the entire system.Then,analysis of whether the location of targets can be detected accurately via shared signal in radar module,and whether the communication signals can be demodulated correctly is demonstrated from the collected data.According to the analysis and experiments,1.5 meters resolution can be achieved,and the Rad Com system can complete demodulation correctly.