Research On DOA Estimation Algorithms Of Mixed Signals

With the development of communication technology, the wireless communication environment has become increasingly complex, uncorrelated sources and coherent sources often simultaneously exist in the wireless channel. Most existing DOA estimation algorithms are only for uncorrelated sources or coherent sources, in the case of mixed sources, the DOA estimation algorithms only for independent sources no longer apply. The algorithms only for coherent sources are still valid, but they can't distinguish between uncorrelated sources and coherent sources, as the result the loss of array aperture is large. What's more, independent sources may produce interference with coherent sources, reduce the DOA estimation performance.This paper studies the basic signal model and coherent signal model, the important parameter estimation algorithms and signal decoherent technologies. In view of the mixed sources situation, a modified algorithm for DOA estimation of mixed signals is proposed in this paper. The DOAs of incoherent signals are estimated using traditional MUSIC algorithm firstly, spatial smoothing is then performed iteratively to the covariance matrix corresponding to the coherent signals to get the DOAs of coherent signals. With the results of two steps, we can get all the DOAs we need.Compared with the traditional spatial smoothing algorithm, the modified algorithm estimate the DOAs of independent sources and coherent sources separately, it can estimate the DOAs of mixed signals accurately and resolve more signals, it is more accurate when the SNR is low.