In this paper, we investigate the prob-lem of angle of arrival (AOA) tracking for the large-scale array in terahertz (THz) communication, which has a large size and a narrow beam, highly demand-ing an accurate angle estimation. On the one hand, the system usually adopts a hybrid structure with limited radio-frequency (RF) chains, which increases the difficulty of angle estimation; on the other hand, the rapid mobility of users also brings new chal-lenges to angle estimation. To address the above challenges, a two-stage tracking framework is pro-posed in this paper, which employs the random phase matrix and orthogonal long pilots in the first stage to reduce the complicated multi-user estimation to multiple single-user estimations, followed by using both wide and narrow beams in the second stage to serve high-speed and low-speed users. Furthermore, a generalized-approximated-message-passing (GAMP) method is proposed for facilitating a low-accuracy es-timation of the angles, followed by adopting a modi-fied expectation-maximization (EM) algorithm based phase estimation to unbiased estimate the instanta-neous angle with the help of high-gain characteristics of the beams. The proposed structure can not only simplify the estimation complexity, but also improve the estimation accuracy due to its capability of trans-ferring the non-linear problem of angle observation into a linear gaussian model. In addition, the Kalman tracking framework is employed for performing a con-tinuous angle tracking. Numerical results show that the angle estimation based on the random phase ma-trix in the initial stage can obtain a high enough es-timation accuracy, while the GAMP algorithm imple-mented in the second stage can quickly capture the an-gle range under the Rayleigh limit. The performance of the proposed EM-based tracking method is shown to outperform the traditional extended Kalman filter (EKF) method.

Chen Zheng;Dekang Liu;Xuhui Ding;Xiangyuan Bu;Zhongshan Zhang

School of Information and Electronics,Beijing Institute of Technology,Beijing 100081,China

中国通信（英文版）

[1]Chen Zheng;Dekang Liu;Xuhui Ding;Xiangyuan Bu;Zhongshan Zhang-.A Novel Angle of Arrival Tracking Method in Large-Scale-Array Systems)[J].中国通信（英文版）,2022(09):171-190

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