Research On High-resolution Algorithm Of DOA Estimation For Wideband Signals And Relevant Dimension Reduction Methods

Direction of arrival(DOA) estimation, which is an important part in array signal processing, has attracted the attention of many researchers in the fields of wireless communication, radar and seismic exploration.Focusing on the research background and its objectives, wideband signal DOA estimation algorithms and relevant dimension reduction methods are studied in this paper based on uniform linear array model.Firstly, the parper gives the assumption of physical environment and discusses the factors that influence the spatial spectrum estimation and the related evaluation estimation performance. Then the wideband signal model in the frequency domain that based on narrowband signal model is studied. Two kinds of weighting incoherent signal subspace method(ISM) are simulated at last.Then the coherent signal subspace method(CSM) is introduced. The common four methods of focusing matrix constructing, including diagonal transformation method, rotational signal subspace(RSS) algorithm, signal subspace transformation(SST) algorithm and two-sided correlation transform(TCT) algorithm are investigated here. TCT algorithm is improved at last to overcome the problem of high resolution threshold.Thirdly, to avoid the shortcoming of the CSM method, which requires preliminary DOA estimation, test of orthogonality of projected subspace(TOPS) algorithm and test of orthogonality of frequency subspace(TOFS) algorithm are studied. The improved TOFS algorithm based on matrix reconstruction is proposed to solve the problem that the original TOFS algorithm cannot process coherent signals.After that, two dimension reduction methods for DOA estimation, which are the multistage wiener filter technology and beam space preprocessing method, are studied. The MSWF and beam space preprocessing methods are introduced to the improved TCT and TOFS algorithms to reduce the computational complexity with the performance maintenance of the original algorithms.With processing the real-measured data from microwave anechoic chamber, the algorithm in this paper is verified in the end. The experimental results show that the algorithm can estimate the DOA of the measured data effectively.