Resratch On The Key Technology Of Constant Envelop OFDM Radar-communication Integration

With the development of technology,modern war is becoming more and more electronic and informative,which makes higher requirements of performance for airborne equipment.Miniaturization of the equipment and multi-platform cooperative combat are the focus of the research.Radar and communication system has similar technical principles and system structure,therefore,the study of radar-communication integration becomes very important.This thesis focuses on the integration of radar communication technology,mainly on the signal design research.The main work is as follows:Analysis of radar and communication systems.This thesis studies the feasibility of the integration of radar and communication from the aspects of technical principle,system structure and technical details,.the thesis analyzes the key parameters ambiguity function and intercept probability as the starting point and criterion of the following research.Analysis of the existing radar system.From the simple pulse radar to other radar systems such as LFM(linear frequency modulation)radar,phase coded radar and OFDM radar,the thesis analyzes the ambiguity function and autocorrelation function of these radar systems.The thesis analyzes the system structure and implementation principle of OFDM system,which is the focus system.By simulation,the influence of modulation information and other parameters on the detection performance of OFDM radar is analyzed,.Then,the thesis studies the problem of high PAPR(peak average power ratio)of OFDM radar.The performance of constant envelope OFDM system is studied.Using the method of phase modulation of OFDM data,the PAPR of OFDM system is reduced to zero.This thesis,studies the basic principle of constant envelope OFDM,and the bit error rate and spectrum performance of CE-OFDM communication system are simulated and analyzed.The phase encoding of the CE-OFDM system is carried out by cyclically shifting the P4 code having the ideal periodic autocorrelation function to form a complementary set.The ambiguity function and autocorrelation function of CE-OFDM system are analyzed by simulation.The results show that the system has an ideal thumbtack ambiguity function and narrow sidelobes,which means the detection performance is good.Based on the principle of CE-OFDM radar and communication system,the architecture of radar-communication integration system based on constant envelope OFDM is given.A method of communication data weighting is proposed to improve the radar performance of the radar-communication integration system of CE-OFDM.In the integration system,the random communication information will affect the performance of radar.In extreme cases,such as each subcarrier has the same data,the time autocorrelation function sidelobes exhibited an underlying triangular shape,and the performance is deteriorated seriously.In this thesis,a method of weighting the communication data is proposed.Using P4 code which has the ideal periodic autocorrelation function,the communication information is multiplied by the sequence to improve the correlation of the random communication information.The simulation results show that the method can reduce the sidelobe level of the time autocorrelation function of the integrated system,and the performance of the performance can be improved by about 4d B comparing with that before weighting.