Performance of the SMI beamformer with signal steering vector errors in heterogeneous environments

• We consider the performance of the SMI beamforming in terms of output SINR.
• Both steering vector Mismatch and environmental heterogeneity are considered.
• Approximate expression is derived for the output SINR of the SMI beamforming.

In this paper, the performance of the sample matrix inversion (SMI) beamformer in heterogeneous environments is examined by taking into account mismatches in the signal steering vector. In a heterogeneous environment, the test and training data have different covariance matrices. An approximate expression for the expectation of the normalized output signal-to-interference-plus-noise ratio (SINR) (i.e., the average SINR loss) is derived with the consideration of both the signal steering vector mismatch and environmental heterogeneity. Simulation results show that the analytical results are very close to the results obtained by using Monte Carlo techniques. This theoretical expression can be used to facilitate the performance evaluation of the SMI beamformer in real scenarios where the mismatch and heterogeneity cannot be neglected.