The MVDR guided constant modulus adaptive array (MVDR-GCMARY) for signal separation in fading channels

Abstract

The constant modulus array (CMARY) is a blind adaptive beamformer, which is capable of recovering a narrowband signal that is received along with other cochannel signals without using a pilot or training signal. It is based on the constant modulus algorithm (CMA) The CMARY typically captures the signal that has the greatest power among the cochannel signals received by the array. In order to help the beamformer select-the desired signal, the capture process should be controlled, or guided, by controlling the initial weights of the array. This can be done by using a suitable method for direction of arrival (DOA) estimation, such as subspace-based methods, e.g. the MUSIC algorithm, to estimate the angle of arrival of the desired signal. The initial weights of the array are then computed using a suitable beamforming technique such as MVDR to recover the desired signal. By this way the desired signal will have a dominant power at the array output and the CMARY array will capture the desired signal. The resulting configuration is named the MVDR guided constant modulus array (MVDR-GCMARY) and is described in detail in this paper. Computer simulations show the high efficiency of the proposed GCMARY in separating cochannel signals received from different sources and directions for different scenarios of signal constellations, array geometries and channel fading and multipath characteristics.