Wideband DOA estimation for SOBFN

This study considers the problem of wideband direction of arrival (DOA) estimation for spatial optical beam‐forming network (SOBFN). Since its system configuration is different from that of the traditional microwave beam‐forming networks, the authors first establish the observation model of SOBFN when multiple broadband signals are received. Two kinds of DOA estimation strategies are proposed for wideband direction finding based on the established signal model. The proposed methods decompose the wideband array output into narrowband outputs in several discrete frequency bins. Then, they take advantages of the spatial sparsity of the discrete narrowband observation models to estimate the spatial power spectrum, either coherently or non‐coherently. A coarse DOA estimate is obtained via peak‐searching in the reconstructed spectrum. The preliminary result is then refined by a linear interpolation procedure. Profound experiments are carried out to demonstrate and compare the performance of the two strategies. Simulation results show that the proposed approaches can achieve wideband DOA estimation of high precision and super‐resolution for SOBFN. Moreover, coherent process is proved to have superior performance than the non‐coherent strategy.