A Novel Angle of Arrival Tracking Method in Large-Scale-Array Systems

In this paper,we investigate the problem of angle of arrival(AOA)tracking for the largescale array in terahertz(THz)communication,which has a large size and a narrow beam,highly demanding 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 challenges to angle estimation.To address the above challenges,a two-stage tracking framework is proposed 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 estimation of the angles,followed by adopting a modified expectation-maximization(EM)algorithm based phase estimation to unbiased estimate the instantaneous 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 transferring the non-linear problem of angle observation into a linear gaussian model.In addition,the Kalman tracking framework is employed for performing a continuous angle tracking.Numerical results show that the angle estimation based on the random phase matrix in the initial stage can obtain a high enough estimation accuracy,while the GAMP algorithm implemented in the second stage can quickly capture the angle 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.

Tracking multiple targets in MIMO radar via adaptive asymmetric joint diagonalization with deflation

In view of the low performance of adaptive asymmetric joint diagonalization（AAJD）, especially its failure in tracking high maneuvering targets, an adaptive asymmetric joint diagonalization with deflation（AAJDd） algorithm is proposed. The AAJDd algorithm improves performance by estimating the direction of departure（DOD） and direction of arrival（DOA） directly, avoiding the reuse of the previous moment information in the AAJD algorithm.On this basis, the idea of sequential estimation of the principal component is introduced to turn the matrix operation into a constant operation, reducing the amount of computation and speeding up the convergence. Meanwhile, the eigenvalue is obtained, which can be used to estimate the number of targets. Then, the estimation of signal parameters via rotational invariance technique（ESPRIT） algorithm is improved to realize the automatic matching and association of DOD and DOA. The simulation results show that the AAJDd algorithm has higher tracking performance than the AAJD algorithm, especially when the high maneuvering target is tracked. The efficiency of the proposed method is verified.

Key Techniques of Terminal Correction Mortar Projectiles

The operational principle, the impulse force and terminal guidance laws of terminal correction mortar projectiles（TCMP） are researched in this paper, by using the TCMP simulation program, key techniques such as the miss distance influenced by the acting point of impulse force, the impulse force value, the correction threshold, and the number of impulse rockets are researched in this paper. And the dual pulse control scheme is also studied. Simulation results indicate that the best acting point is near the center of gravity, sufficient correction resources are needed, the miss distance is insentive to the correction threshold, increasing the number of impulse rockets properly is beneficial to increase the hit precision, the velocity pursuit guidance law has less miss distance, the change of the attack angle is milder and the transient time becomes less in the dual impulse control scheme. These conclusions are important for choosing parameters and impulse correction schemes designed for TCMP.