Forward/backward spatial smoothing techniques for coherent signal identification

Abstract

In the context of coherent signal classification, a spatial smoothing scheme first suggested by Evans et al., and subsequently studied by Shan et al., is further investigated. It is proved here that by making use of a set of forward and complex conjugated backward subarrays simultaneously, it is always possible to estimate any K directions of arrival using at most 3 K / 2 sensor elements. This is achieved by creating a smoothed array output covariance matrix that is structurally identical to a covariance matrix in some noncoherent situation. By incorporating the eigenstructure-based techniques on this smoothed covariance matrix, it then becomes possible to correctly identify all directions of arrival irrespective of their correlation.

Two Uniform Linear Arrays for Non-Coherent and Coherent Sources for Two Dimensional Source Localization

“…The proposed method has several advantages over the methods in [5][6][7][8][9][10][11][12][13][14][15][16]. First, the proposed method does not require spatial smoothing [3,4] which results in a reduction in the computational complexity and cost. Second, the proposed method can estimate the DOA of coherent sources at very low signal-to-noise ratios (SNR).…”

“…While there is a severe degradation in the accuracy of DOA estimation in the presence of partially correlated sources, these methods fail when highly correlated and coherent signals are present. A spatial smoothing technique was introduced in [3,4] to improve the system performance and estimation accuracy. However, one side effect of this spatial smoothing technique is the increase in the computational complexity of the algorithm.…”

Blind Unitary Prewhitening with a Real-Valued Eigendecomposition

“…It is well known that by using FB averaging the number of snapshots can be nearly doubled and possibly correlated source pairs can be decorrelated [9], [11]. The latter facts often lead to improvement of the estimation accuracy for the methods that use R F B as compared to the methods that use R y (0).…”

“…The proposed procedure makes use of forward-backward (FB) averaging [9], [11] and the aforementioned transformation of a complex-valued covariance matrix into a real-valued one. Therefore, it can be applied only to axissymmetrical arrays [7].…”

Blind Direction of Arrival Estimation of Coherent Sources Using Multi-Invariance Property

“…Eigen-decompositionbased methods, including multiple signal classification (MUSIC) and estimation of signal parameters via rotational invariance techniques (ESPRIT), have high resolution DOA estimation performance, but they fail to work in coherent signal condition. Some smoothing methods including spatial smoothing techniques [18,19], subspace smoothing techniques [21], temporal smoothing techniques [22] etc. were proposed to resolve this coherent problem.…”