Subspace estimation of coherent wideband OFDM signals

Abstract A method for estimating signal and noise subspaces in the context of direction of arrival (DOA) for coherent wideband orthogonal frequency-division multiplexing (OFDM) signals is proposed. It relies on a newly defined matrix, which leverages the orthogonality property of OFDM subcarriers. We mathematically demonstrate that this matrix satisfies adequate subspace decomposition by considering two approximations. Furthermore, through DOA estimation evaluations, we confirm its effectiveness in discerning DOAs even with reduced snapshots and a low signal-to-noise ratio. To validate its feasibility and effectiveness, practical experiments are conducted using a real-world testbed based on USRP-B210 boards, and the results demonstrate the method’s effectiveness.