DOA Estimation For Coherent Signals

The DOA (Direction-Of-Arrival) estimation of coherent signals is a key problem in array signal processing which has been widely used in radar, communication and sonar etc. In this paper, the research on coherent DOA estimation of narrowband signals in the far field is investiaged.Firstly, two kinds of commonly used algorithms for coherent signals were summarized and campared. The spatial smoothing algorithm is an effectively DOA estimation algorithm of coherent signals, whose performance is good with low computational complexity and easy to implemented. However, The effective aperture of array will be reduced because the ability of decorrelation was gain based on sacrificing the effective number of arrays, and, in the circumstance of lower SNR(signal-noise-ratio) , the estimation performance is deteriorated. Another coherent DOA estimation method using ESPRIT algorithm is proposed, which reconstructs an array model based on Toeplitz matrices whose rank is only related to the DOA of signals and cannot be affected by the coherency between them. Simulation results show a better performance that this algorithm is far superior to conventional spatial smoothing techniques.Secondly, Multi-invariance ESPRIT algorithm, Multi-invariance MUSIC algorithm and trilinear decomposition-based algorithm which are based on Toeplitz matrices are proposed. Simulation results show that the performance is obviously better compard to the conventional algorithm we mentioned above, and these three methods are able to break the restriction in signal number where common Toeplitz matrix reconstruction algorithm have.Finally,a 2-D DOA estimation method of coherent signal with a crossed array is proposed, and it is simple and easy to implemented. Simulation results reveal that this algorithm has a better two-dimensional DOA estimation performance compard to the current two-dimensional estimation algorithm, and it has low computational complexity and high resolution characteristics.