Broadband Doa Estimation Subspace Algorithm And Its Application Research On Ofdm

DOA(direction of arrival) estimation, which has been investigated greatly in recentyears, has been widely applied in mobile and satellite communication systems,information warfare, radar, passive sonar, seismology, astronomy, navigation, videoconferencing, time series analysis and spectrum estimation. The current efficientalgorithms of DOA estimation are mostly based on the hypothesis of narrow-bandsignal. With the increasing demands of communication technologies, wide-band signalsare used more and more widely in communication systems. Therefore, the research onwide-band signals direction detection has become one of the most important topics.Firstly, the wide application of DOA estimation and the research significance of thepassive DOA estimation algorithm are summarized in this paper respectively, then thestate of art research results, development of the narrowband signal and wideband signalDOA estimation algorithm are introduced. Since the sub-space algorithm outperformsbetter estimation performance than other DOA estimation algorithm, the topic of thispaper will be limited in this field. After the classification of the sub-space algorithmaccording to the data models, the state of art algorithms are presented in this paper.The broadband signal data model based on the complex envelop, which is widelyused in most of the broadband signal subspace algorithms, is introduced at first. Thesub-space algorithms, such as ISSM, CSSM, WAVES, TOPS, which are based on thisdata model, are developed from the traditional narrowband signal subspacedecomposition method.TOPS algorithm is different from ISSM estimation algorithm, which uses everysub-band data independently at one time estimation, TOPS can treat and utilize themultiple frequency data component of the broadband signal, so TOPS can avoid the lowstability of each independent sub-band estimate performance. Also different fromCSSM method, without any data correlation combination process, TOPS do not needrelated focus angle of estimation methods, and focus angle error may introduceinevitable DOA estimation error. A novel low rank model, which based on the spline interpolation, is introduced inthe broadband signal DOA estimation algorithm. Different from the traditionalwideband DOA estimation algorithm, it does not need the filter group or DFT to devidethe wideband signals into many sub-band signals. Based on a short period of time ofcollected data samples, this method can produce accurate position parameter estimation.This algorithm can be applied to any array structure, and can be applied to the near fieldor the far field source localization problems.Finally TOPS algorithm and low rank model algorithm are applied to estimate theactual signal DOA, an OFDM signal according with the standard of DVB-T. Theadvantages and disadvantages of the two kinds of OFDM signal DOA estimationalgorithm will be analyzed. For the low performance of the TOPS algorithm in the highsignal-to-noise ratio situation, two ideas of improving methods will be proposed. Forthe low estimate rank model, a parameter choice method which is conducive to theperformance will be put forward.