An IDFT approach for coprime array direction-of-arrival estimation

In massive multiple-input multiple-output (MIMO) systems, efficiently estimating both the direction-of-arrival (DOA) and the source power with an increased number of degrees-of-freedoms (DOFs) is important but challenging. Aiming at this, we introduce the framework of coprime array signal processing into massive MIMO system and propose an efficient inverse discrete Fourier transform (IDFT)-based DOA estimation algorithm in this paper. By implementing IDFT on the second-order virtual array signals characterized by the equivalent spatial frequency, it is proved that the resulting spatial response enables to effectively estimate both DOA and source power with an increased number of DOFs. Meanwhile, the window method and the zero-padding technique are sequentially considered to alleviate the spectral leakage phenomenon and improve the DOA estimation accuracy. Compared with the existing coprime array DOA estimation algorithms, the implementation of IDFT indicates a remarkably reduced computational complexity as well as the hardware overhead. Simulation results show the effectiveness of the proposed algorithm.