DOA Estimation in Systems with Nonlinearities for MMWAVE Communications

Abstract

Accurate and efficient methods for Direction of Arrival (DOA) estimation play an important role in mmWave channel estimation methods. This estimation procedure can potentially be affected by the different RF and analog components in the communication system. Such components add an unknown, nonlinear distortion to the received signal. We address the DOA estimation problem for a general nonlinear distortion of the received signal. Two different angle recovery scenarios are considered: with and without the use of pilot symbols. The analysis focuses on the transformation of the signal subspace, resulting from the communication system nonlinearities. We prove that under certain conditions on the nonlinearity, the signal subspace is preserved. The derived result implies that the angles can be recovered without calibrating or inverting the nonlinearity.