One Method For Low Elevation Estimation Based on Unitary transformation in MIMO Radar

Abstract

Multipath effection seriously affect the low elevation Angle estimation in MIMO radar,This paper Establish the multipath signal model , and put forward a kind of secondary general MUSIC algorithm based on unitary transformation (DU-G_MUSIC). First Based on general MUSIC algorithm, a joint estimation algorithm of elevation angle and multipath fading coefficient about target is proposed , In order to reduce the computational complexity, Avoiding search a wide range of angles, Then use the characteristics of the unitary transformation matrix, structure of real number domain data, get the initial estimation of low elevation Angle, And on the basis of initial estimates to obtain the real value of multipath fading coefficient, finally the DU-G_MUSIC algorithm on the real number field is used to estimate the optimized low elevation values. Due to multipath fading coefficient combined with Angle estimation, greatly improve the efficiency of the operation, to avoid the tedious decorrelation smoothing procedure, get high Angle resolution, on the premise of no loss of array aperture, reduces to the special requirements of array structure, has high engineering value. Introduction New system of multiple input multiple output (MIMO) radar, is a hotspot in research of radar at home and abroad, In recent years, many scholars study the characteristics of MIMO radar from different angles. because of the wide beam, makes the multipath signal produced by intensifying, On the other hand make use of orthogonal waveform, At the same time bring frequency diversity and space diversity, Can reduce the probability of multipath signal cancellation, effectively suppress multipath clutter interference. The transmission and reception multipath MIMO radar needs to consider at the same time, after dealing with the receiver matched filter effective channel number is M times that of the conventional radar, dealing with computational complexity. Therefore, based on the decorrelation processing algorithms cannot be directly applied to the multipath channel model of MIMO radar Angle estimation. By improving the super resolution algorithm can effectively solve the problem of covariance matrix rank loss, but will reduce the effective aperture antenna, reduce angular resolution. To do this, such as generalized MUSIC algorithm is presented to directly solve multipath, coherent Angle estimation problem by Zoltowski Et al For the multipath MIMO radar low elevation Angle estimation under the background of the research is relatively small, Literature proposed one method based on maximum likelihood estimation, need spectrum peak search, computational complexity. By means of matrix of beam characteristics, effectively overcome the multipath effect, achieve low elevation Angle estimation. Low elevation algorithm was proposed based on the beam space, greatly simplify the calculation, make full use of the MIMO radar beam characteristics. One algorithm is presented based on the quadratic differential pretreatment, this algorithm has nothing to do with the signal environment, has a good robustness. Above the low elevation Angle estimation algorithm for MIMO radar are conducted on complex domain, Angle estimation computation is lager. This paper in the complex domain complete the joint estimation of incident Angle and the multipath attenuation coefficient with generalized MUSIC algorithm, the Angle measuring precision is improved greatly. In order to further reduce the computational complexity, avoid search a wide range of perspectives, Then based on the unitary transformation matrix characteristics, structure the International Conference on Advances in Mechanical Engineering and Industrial Informatics (AMEII 2015) © 2015. The authors Published by Atlantis Press 1300 data matrix for real number domain, get the multipath Angle initial estimation. And on the basis of initial estimates to get the multipath attenuation coefficient for real number domain, put forward a kind of secondary general MUSIC algorithm based on unitary transformation (DU-G_MUSIC). Due to multipath fading coefficient combined with Angle estimation, greatly improve the efficiency of the operation, to avoid the tedious decorrelation smoothing procedure, get high Angle resolution, on the premise of no loss of array aperture, reduces to the special requirements of array structure, has high engineering value. The signal model MIMO radar is a new system radar, launch multiple orthogonal signal, have multiple channels. So not only need to consider accepting multipath, but to consider multipath launch, As shown in figure 1.