The Study Of The Spatial Smoothing Approach To DOA Arrival Estimation Of Coherent Signals In Smart Antenna

Beamforming algorithm has recently developed rapidly; quite a lot of technical problems still need to be solved in smart antenna systems (SAS), though. Given the existing problems, a representative beamforming algorithm in SAS will be introduced systematically in this paper. Meanwhile, the paper also proposes a new way by applying spatial smoothing technology to pretreatment of the beamforming algorithms.In SAS, the problem of DOA estimation of coherent signals in fading channels has become an important one for certain applications. Therefore, an effective method to estimate the source coherency structure for uniform circular array is presented in this paper. By utilizing spatial smoothing technique, the uniform circular arrays (UCA) are transformed in element space into a virtual uniform linear array (ULA). Afterward, a special telescoping submatrix sequence can be obtained, from which the smoothed rank profile (SRP) of the virtual ULA is determined. The SRP is the key to estimate the source coherency structure and total signal number.Temporal smoothing, this approach is similar to spatial smoothing, but we use it to extract a set of Q subvectors of length d at each antenna with the extraction procedure. Theoretical results demonstrate that, given K directions of arrival, temporal smoothing requires K+1 sensor elements while spatial smoothing requires 2K elements. Therefore the computation quantity of algorithms will be decreased correspondingly.