Non-coherent Off-grid DOA Estimation with Magnitude-only Measurements under a Linear Model

Recently, some non-coherent direction-of-arrival (DOA) estimation methods with magnitude-only measurements have been developed under a sparsity framework, where the DOAs of incident signals are assumed to be on the predefined grid points implicitly. However, this assumption does not often hold; in order to address this issue, an efficient two-step method is developed. Specifically, the non-linear signal model is approximated by an linear one involving off-grid bias by introducing a high power reference signal, and the signal model can be seen as a linear combination of cosine waves with different frequency components, based on which an off-gird signal model is presented and the corresponding DOA estimation method is developed. Numerical simulations show that, compared to existing magnitude-only DOA estimation methods, a better performance is achieved by the proposed one.