Spatial Structure Matching-Based DoA Estimation and Tracking for Integrated Sensing and Communication Massive MIMO OFDM System.

In this paper, a direction of arrival (DoA) estimation and tracking scheme based on spatial structure matching is proposed for integrated sensing and communication (ISAC) massive multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Firstly, the frame structure that enables DoA estimation and tracking as well as data transmission is introduced. Then, a pilot signal preprocessing method for robust DoA estimation and tracking is proposed, including suppression of beam squint effect and multipath combination of pilot sequences. Finally, a DoA estimator design based on spatial structure matching for ISAC massive MIMO-OFDM system is proposed, including an initial DoA estimation scheme based on preamble and a DoA tracking scheme based on embedded pilot. The simulation results show that the proposed spatial structure matching based DoA estimation and tracking method can adapt to the dynamic changes of scattering environment and obtain accurate DoA estimation under low signal-to-noise ratio, and the estimation performance is superior to the traditional multiple signal classification (MUSIC) and estimation of signal parameters via rotational invariance technique (ESPRIT) methods and their spatial smoothing enhancement schemes. Moreover, the computational complexity of the proposed scheme is significantly lower than that of the MUSIC and ESPRIT methods.