  Matrix pair beamformer (MPB) is a blind beamformer. It exploits the temporal
structure of the signal of interest (SOI) and applies generalized
eigen-decomposition to a covariance matrix pair. Unlike other blind algorithms,
it only uses the second order statistics. A key assumption in the previous work
is that the two matrices have the same interference statistics. However, this
assumption may be invalid in the presence of multipath propagations or certain
"smart" jammers, and we call it as matrix mismatch. This paper analyzes the
performance of MPB with matrix mismatch. First, we propose a general framework
that covers the existing schemes. Then, we derive its normalized output SINR.
It reveals that the matrix mismatch leads to a threshold effect caused by
"steering vector competition". Second, using matrix perturbation theory, we
find that, if there are generalized eigenvalues that are infinite, the
threshold will increase unboundedly with the interference power. This is highly
probable when there are multiple periodical interferers. Finally, we present
simulation results to verify our analysis.
