Two Rapid Power Iterative DOA Estimators for UAV Emitter Using Massive/Ultra-Massive Receive Array

To provide rapid direction finding (DF) for unmanned aerial vehicle (UAV) emitters in future wireless networks, a low-complexity of arrival (DOA) estimation architecture massive multiple-input multiple-output (MIMO) receiver arrays is constructed. In this paper, we propose two strategies to address the extremely high complexity caused by eigenvalue decomposition received signal covariance matrix. Firstly, power iterative rotational invariance (RPI-RI) method proposed, which adopts subspace generated iteration obtain final through between subarrays. RPI-RI causes significant reduction at cost substantial performance loss. order further reduce and good directional measurement results, polynomial rooting (RPI-PR) utilizes noise combined with solution optimal estimation. addition, influence initial vector selection on convergence analyzed, especially when orthogonal incident wave. Simulation results show that proposed methods outperform conventional DOA terms computational complexity. particular, RPI-PR achieves more than orders magnitude lower close Cramér–Rao Lower Bound (CRLB). Moreover, it verified relative error have impact respect