Performance of decoupled direction finding based on blind signal separation

A number of methods for blindly separating superimposed digitally modulated signals arriving at an antenna array have been proposed. These techniques are efficient at the up-link (mobile to base) in a mobile communication system. However, for solving the base-to-mobile beamforming problem it may be necessary to also estimate the directions-of-arrival (DOAs) of the various signal paths. We present an optimal decoupled DOA estimation procedure based on information from the blind separation algorithm. Its performance is evaluated in the presence of spatially correlated noise and array modeling errors. The proposed technique has computational advantages as compared to traditional DOA estimation, because the different signal waveforms are treated in a separated fashion. Yet, the decoupled approach is shown to be substantially less sensitive to modeling errors and interference