Applications of cumulants to array processing. IV. Direction finding in coherent signals case

For pt.III see ibid., vol.45, no.9, p.2253-64, 1997. We present a subspace-based direction finding method for coherent signal environments using an antenna array. Our method, which uses fourth-order statistics, is capable of resolving more signals than a comparable second-order statistics-based subspace method and is applicable to a larger class of arrays. The maximum number of signals resolvable with our method may exceed the number of sensors in the array. Only a uniform linear subarray is needed; the rest of the array may have arbitrary and unknown response and does not require calibration. On the other hand, the comparable second-order statistics-based method is limited to uniform linear arrays only. No search procedure is needed in our method. Simulation experiments supporting our conclusions are provided.