PASI: New narrowband direction-of-arrival estimator using pilot signals

An iterative subspace-based method, termed pilot-aided subarray iterative (PASI) technique, is proposed for estimating directions-of-arrival (DOAs) of correlated narrowband signals impinging at an array. With the use of pilot signals, DOA estimation for each source can be carried out in parallel; with the use of subarrays, correlated signals can be decorrelated by forward spatial smoothing. The inclusion of the iterative procedure further improves the accuracy of the DOA estimates. The PASI technique yields closely-spaced DOAs of high accuracy with only a small number of samples and a small array size. Moreover, it resolves correlated signals adequately at low signal-to-noise ratios (SNRs) with few iterations. The hardware requirement is also relaxed as the maximum number of detectable DOAs is no longer bounded by the number of elements in the array.