MIMO field directionality estimation using orientation-diverse linear arrays

This paper addresses the estimation of power versus azimuth and elevation using a sparse sensor array. In MIMO radar, clutter and noise field directionality can be measured both from the transmit array and to the receive array. In applications where sparse arrays must be used, however, often substantial ambiguities in the field directionality map occur due to spatial under-sampling and/or sidelobe leakage. In this paper, we propose an alternative field-directionality mapping approach which incoherently combines the outputs of several uniform linear arrays with different orientations. The proposed orientation-diverse multi-line array (ODMA) treats the 1-D field directionality estimate from each line array as a projection of a 2-D spatial spectrum. Two methods for reconstruction from these projections are presented: 1) least-squares estimation subject to a positivity constraint, and 2) maximum likelihood estimation using the EM algorithm. Simulation results suggest both methods achieve ODMA field directionality maps with improved ambiguity resolution and sidelobe performance versus conventional beamforming techniques.