  Matrix pair beamformer (MPB) is a promising blind beamformer which exploits
the temporal signature of the signal of interest (SOI) to acquire its spatial
statistical information. It does not need any knowledge of directional
information or training sequences. However, the major problem of the existing
MPBs is that they have serious threshold effects and the thresholds will grow
as the interference power increases or even approach infinity. In particular,
this issue prevails in scenarios with structured interference, such as,
periodically repeated white noise, tones, or MAIs in multipath channels. In
this paper, we will first present the principles for designing the projection
space of the MPB which are closely correlated with the ability of suppressing
structured interference and system finite sample performance. Then a
multiple-interference-channel based matrix pair beamformer (MIC-MPB) for CDMA
systems is developed according to the principles. In order to adapt to dynamic
channels, an adaptive algorithm for the beamformer is also proposed.
Theoretical analysis and simulation results show that the proposed beamformer
has a small and bounded threshold when the interference power increases.
Performance comparisons of the MIC-MPB and the existing MPBs in various
scenarios via a number of numerical examples are also presented.
