Research On Range Sidelobe Suppression Method Based On OQAM-OFDM Signal

Range sidelobes are generated during the pulse compression.Accordingly,a weak scatter might be covered when it falls into the high sidelobe areas of a strong scatter,which has a negative influence on the performance of target detection.Recently,due to the similar principles for the radar and communication systems,the integration of radar and communication has become a hot research hotspot to reduce the size and power consumption of an equipment,but the problem of high sidelobes still exists.Offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OQAM-OFDM)signal is an important signal to achieve range sidelobe suppression,because it has the properties of flexible parameter design and high spectral efficiency,and it can effectively resist multipath interference and range sidelobe interference without using a cyclic prefix,compared with the OFDM signal.Thus,this dissertation mainly studies the range sidelobe suppression method based on the OQAM-OFDM signal for radar detection and the integration of radar and communication.The main work and contributions are as follows:1.A range sidelobe suppression method based on the frequency domain estimation for the OQAM-OFDM signal is proposed(FDPCM).The detectability problem of the OQAM-OFDM radar is achieved by demodulating the received signal and estimating the weighted radar cross section coefficient and the Doppler frequency based on the interference approximation method.Besides,the influence of Doppler frequency shift is overcome and the range sidelobes are effectively suppressed.2.A range sidelobe suppression method based on the time domain estimation for the OQAM-OFDM signal is proposed(TDPCM).By whitening the demodulated received signal,the range sidelobe suppression problem is transformed into a linear model.Through solving the linear model,the problem of FDPCM,which has a large limitation on the number of subcarriers and the number of range cells,has been overcome.Furthermore,the proposed TDPCM realizes the inter-range-cell interference(IRCI)-free pulse compression.3.A range sidelobe suppression method based on the OQAM-OFDM signal design by using the majorization-minimization(MM)algorithm is proposed.Through the theoretical derivation analysis and optimizing the subcarrier sequence of the OQAM-OFDM signal,the output signal-to-noise ratio(SNR)of the TDPCM is maximized,and the range sidelobe suppression capability is further improved.4.A range sidelobe suppression method based on the linear model for the OQAMOFDM signal is proposed.By constructing the received signal as a linear model and solving it,the additional computational load of demodulation for the received signal is avoided,and the IRCI-free pulse compression is realized.5.A range sidelobe suppression method based on the OQAM-OFDM signal design for the integration of radar and communication is proposed.By introducing weights into OQAM-OFDM signal and optimizing them,the radar output SNR is maximized under the requirement of ensuring the communication SNR.The proposed method realizes the performance improvement for both of the radar and communication systems.In this dissertation,the performance of the above proposed methods is theoretically analyzed and verified by simulations.The results show that the proposed methods can successfully suppress the range sidelobes for both radar detection and the integration of radar and communication.