This paper is concerned with the problem of simultaneously tracking the direction-of-arrival (DOA) of far-field multiple moving sources/users in wireless communications using the vector-signal received by an antenna array of N elements. The antenna array can be rigid (fixed array locations) or flexible (time-varying array locations), and it is used in conjunction with a "manifold extender", a spatiotemporal state-space model and a Kalman-type tracking approach for non-stationary wireless channels. In particular, two tracking approaches are proposed. The first is based on an arrayed Extended Kalman Filter (arrayed-EKF) algorithm and the second on an arrayed Unscented Kalman Filter (arrayed-UKF) algorithm. Furthermore, if the array is rigid the spatiotemporal state-space model incorporates the DOAs and the angular velocities of the sources, while if it is flexible it also includes the array locations in the set of statevariables. The performance of the two approaches using both rigid and flexible arrays is evaluated using computer simulation studies and compared with a subspace tracking algorithm and a particle filter method under the same conditions. The results show that the arrayed-UKF and the arrayed-EKF show superior tracking performance, especially for low SNRs.
Index Terms-Array processing, flexible array, DOA tracking, extended Kalman filter, unscented Kalman filter, spatiotemporal arrays, array manifolds, extended manifolds Zhuqing Tang (S'17) received the B. Eng. Degree (with Hons.) in Electronic and Communication Engineering from University of Liverpool, U.K., in 2016, and the M.Sc. degree in Communications and Signal Processing from Imperial College London, U.K., in 2017. She is currently pursuing the Ph.D. degree with the Communications and Signal Processing group, Department of Electrical and Electronic Engineering, Imperial College London, U.K., under the supervision of Prof. A. Manikas. Her research interests include array communications, array signal processing, flexible array signal processing, beamforming, and source tracking.