  A simple scheme for joint direction of arrival (DOA) and array manifold
estimation for a MIMO array system is proposed, where only two transmit
antennas are calibrated initially. It first obtains a set of initial DOA
results by employing a rotational invariance property between two sets of
received data, and then more accurate DOA and array manifold estimation is
obtained through a local searching algorithm with several iterations. No strict
half wavelength spacing is required for the uncalibrated antennas to avoid the
spatial aliasing problem.
