Beam space weighted subspace fitting algorithm

The sensor space high resolution Weighted Subspace Fitting (WSF) algorithm is expanded into beam space in this paper. Beam space WSF algorithm uses beam outputs of array which can be regarded as the outputs of an virtual array having the same number of elements as the beam number to estimate target directions. In most underwater acoustic systems, the number of beams used for determining the direction of arrival is usually considerably less than that of the sensors, so the computation burdensome is decedent. Computer simulation results show that the beam space WSF algorithm retains the super performance of the sensor space WSF algorithm when applied to the beam outputs of some practical acoustic-receiving array.

Reducing subspaces of tensor products of weighted shifts

A unilateral weighted shift A is said to be simple if its weight sequence {α_n} satisfies ▽~3(α_n^2)≠0for all n≥2.We prove that if A and B are two simple unilateral weighted shifts,then AI+IB is reducible if and only if A and B are unitarily equivalent.We also study the reducing subspaces of A^kI+IB^l and give some examples.As an application,we study the reducing subspaces of multiplication operators Mzk+αωl on function spaces.

Target parameter estimation for OTFS-integrated radar and communications based on sparse reconstruction preprocessing

Orthogonal time-frequency space(OTFS)is a new modulation technique proposed in recent years for high Doppler wireless scenes.To solve the parameter estimation problem of the OTFS-integrated radar and communications system,we propose a parameter estimation method based on sparse reconstruction preprocessing to reduce the computational effort of the traditional weighted subspace fitting(WSF)algorithm.First,an OTFS-integrated echo signal model is constructed.Then,the echo signal is transformed to the time domain to separate the target angle from the range,and the range and angle of the detected target are coarsely estimated by using the sparse reconstruction algorithm.Finally,the WSF algorithm is used to refine the search with the coarse estimate at the center to obtain an accurate estimate.The simulations demonstrate the effectiveness and superiority of the proposed parameterestimation algorithm.

Doppler distributed clutter model of airborne radar and its parameters estimation

To characterize the clutter spectrum center-shift and spread of airborne radar caused by the platform motion, a novel Doppler Distributed Clutter (DDC) model is proposed to describe the clutter covariance matrix in temporal domain. Based on this parametric model, maximum likelihood, subspace based method and other super- resolution methods are introduced into the Doppler parameters estimation, and more excellent performance is obtained than with the conventional approaches in frequency domain. The theoretical derivation and real experimental results are also provided to validate this novel model and methods of parameter estimating.