Experimental DOA Estimation for Coherent Wideband OFDM Signals Based on Subspace Techniques Using SDR Boards

This paper proposes a novel direction of arrival (DOA) estimation algorithm for coherent wideband orthogonal frequency‐division multiplexing (OFDM) signals. The method introduces a specifically designed total subspace matrix that leverages the intrinsic orthogonality of OFDM subcarriers. Processing starts with a zoomed discrete Fourier transform (ZDFT) applied to the received signals within the operational bandwidth. The total subspace matrix is subsequently constructed, followed by eigenvalue decomposition to determine the signal and noise subspaces, enabling subspace‐based DOA estimation. Simulation results demonstrate that the proposed method outperforms existing techniques, especially under low signal‐to‐noise ratio (SNR) conditions and with a limited number of snapshots, achieving superior estimation accuracy and enhanced spatial resolution. The algorithm is experimentally validated using a USRP‐B210 software‐defined radio testbed, confirming its practical efficacy. Consistent performance in both simulations and measurements validates the reliability of the approach for DOA estimation of coherent wideband OFDM signals.