Performance Analysis of the Eigen-Space Projection Beamformer Based on Operator Approach

In this paper, we propose a new approach resulting in an expression for the probability density function (PDF) of the normalized conditioned signal-to-interference-plus-noise ratio for the eigen-space projection beamformer for antenna arrays of arbitrary geometry. The analysis method is based on the first order perturbation expansion of the projection operator. This technique takes advantage of the algebraic simplicity of the perturbation analysis of linear operators. The probability density is derived from the asymptotic properties of the sample covariance matrix estimated from finite samples. It is shown that, unlike the SMI beamformer, the probability density function depends on the interference-plus-noise covariance matrix when the interference-to-noise ratio is not high enough. Computer simulation shows the correctness of the method.