Patent Document ID: 7679560
Application ID: 12119886
Patent Status: 1

Claim One:
1. A direction estimation method for coherent signals in an environment of spatially correlated additive noise, where a specified number (=p<M/2) of coherent signals are received by a uniform linear array with multiple (=M) antenna elements, and a length of a spatial correlation of the noise is assumed to be q (0≦q≦M−1) in which when the correlation between the noise w i (n), w j (n) included in the signals received at the ith and jth antenna elements can be expressed by: 
 E {w i ( n ) w j *( n )}≠0(| i - j |≦ q ), 
 E {w i ( n ) w j *( n )}≠0(| i - j |≦ q ), said direction estimation method comprising: calculating (M−q−1) instantaneous cross-correlations at time n between a signal received at an antenna element and signal s received at the other (M−q−1) antenna elements; selecting multiple pairs of the cross-correlations, each of which is consisted of p instantaneous cross-correlations from the calculated (M−q−1) instantaneous correlations to form a Hankel correlation matrix, and dividing this matrix into an upper and lower correlation matrices; calculating a linear operator at time n from these two upper and lower correlation matrices by using an adaptive LMS algorithm with a fixed or time-varying step-size parameter; estimating a noise subspace by using this estimated linear operator; and estimating the directions of the coherent signals at a predetermined time from the estimated noise subspace by using Newton approximation.