Yide Wang

A non-circular sources direction finding method using polynomial rooting

In this paper, we present a new direction finding algorithm for non-circular sources based on the polynomial rooting technique. Due to the non-circularity characteristics of the impinging sources, the proposed method is able to handle more sources than sensors. Using polynomial rooting instead of a searching technique limits the method to linear uniformly spaced arrays. Polynomial rooting, however, reduces computation cost and enhances resolution power significantly. Computer simulations are used to show the performance of the algorithm.

Polynomial root finding technique for joint DOA DOD estimation in bistatic MIMO radar

In this paper, we propose a new technique to transform the 2-D direction finding in the bistatic MIMO radar into a double 1-D direction finding procedure. Firstly, a search based 2-D MUSIC method to estimate the joint DOA (direction of arrival) and DOD (direction of departure) in multi-target situation is presented. Then, we propose an algorithm based on double polynomial root finding procedure to estimate the DOA and DOD. The proposed method allows an efficient estimation of the target DOA and DOD with automatic pairing. The simulation results of the proposed algorithm are presented and the performances are investigated and discussed.

Efficient Subspace-Based Estimator for Localization of Multiple Incoherently Distributed Sources

In this paper, a new subspace-based algorithm for parametric estimation of angular parameters of multiple incoherently distributed sources is proposed. This approach consists of using the subspace principle without any eigendecomposition of the covariance matrix, so that it does not require the knowledge of the effective dimension of the pseudosignal subspace, and therefore the main difficulty of the existing subspace estimators can be avoided. The proposed idea relies on the use of the property of the inverse of the covariance matrix to exploit approximately the orthogonality property between column vectors of the noise-free covariance matrix and the sample pseudonoise subspace. The resulting estimator can be considered as a generalization of the Pisarenkos extended version of Capons estimator from the case of point sources to the case of incoherently distributed sources. Theoretical expressions are derived for the variance and the bias of the proposed estimator due to finite sample effect. Compared with other known methods with comparable complexity, the proposed algorithm exhibits a better estimation performance, especially for close source separation, for large angular spread and for low signal-to-noise ratio.

Combined ESPRIT-Rootmusic for DOA-Dod Estimation in Polarimetric Bistatic MIMO Radar

In this paper, we investigate the exploitation of the polarimetric diversity signal properties in a bistatic polarimetric MIMO radar to improve the performance of joint estimation of direction of arrival (DOA) and direction of departure (DOD) of targets using combined ESPRIT-RootMUSIC technique. Numerical simulations are carried out to illustrate the performance of the proposed approach.

A root-MUSIC algorithm for non circular sources

We present in this paper a new direction finding algorithm for non circular sources that is based on polynomial rooting. Due to the non circularity characteristics of the impinging sources, the proposed method is able to handle more sources than sensors. By using a polynomial rooting instead of a searching technique the method is limited to linear uniformly spaced arrays. However, polynomial rooting reduces significantly computation cost and enhances resolution power. Computer simulations are used to show the performance of the algorithm.

A modified COMET-EXIP method for estimating a scattered source

The EXtended Invariance Principle (EXIP) has been applied to the structured covariance estimation of a zero-mean Gaussian vector, the resulting method was named COvariance Matching Estimation Techniques (COMET). This technique has been recently used for estimating separately and efficiently the direction of arrival (DOA) and angular spread of a scattered source. Unfortunately, this new technique has an ambiguity that limits its utilization in practice. We show in this paper, the existence and the origin of this ambiguity and we propose a rigorous solution to eliminate this problem without introducing performance degradation. Our approach consists first to add a constraint to the original cost function, and then to replace the constrained problem by an unconstrained problem by using the penalty function method. For the purpose to reduce the computational load of our method, we propose a simple and fast solution to solve this ambiguity problem. Analytical expression for the variance of the unweighted COMET-EXIP estimator is derived and compared with simulation results.

Fast communication: Efficient DSPE algorithm for estimating the angular parameters of coherently distributed sources

In this paper, we consider the problem of estimating the direction-of-arrivals (DOAs) and angular spreads of uncorrelated coherently distributed sources. The proposed method enables a decoupled estimation of the DOAs from that of the angular spreads of sources with small angular spread. Therefore, compared with the original DSPE algorithm, the proposed algorithm improves the robustness to the mismodeling of the spatial distribution of sources at least for two popular distribution shapes (Gaussian and uniform). Furthermore, the proposed method works even in the case where the different sources do not have same angular distribution shape.

Robust Fixed-Complexity Sphere Decoders for Rank-Deficient MIMO Systems

Sphere decoder (SD) has variable complexity, and the traditional fixed-complexity sphere decoder (FSD) is not applicable for rank-deficient (NT > NR) multiple input multiple output (MIMO) systems (i.e. the down link detection in MIMO systems, or systems with highly correlated MIMO channels). To overcome these difficulties, in this paper, robust fixed-complexity sphere decoders (RFSD-s) based on new preprocessing algorithms are proposed for rank-deficient MIMO systems. With respect to the cases without and with information on the level of noise, RFSD using zero-forcing technique (RFSD-ZF) and FSD using minimum mean square error technique (FSD-MMSE) are proposed respectively. To reduce the computational complexity of RFSD-ZF, a simplified RFSD-ZF (SRFSD-ZF) with little performance loss is also introduced, the theoretical proof is given to support the feasibility of SRFSD-ZF. Simulation results show that, besides better performance than the traditional FSD, the proposed techniques are robust to the configuration of MIMO antennas (both NT ≤ NR and NT > NR), which is another advantage over the traditional FSD.

Non circular ESPRIT-RootMUSIC joint DOA-DOD estimation in bistatic MIMO radar

In this paper, we investigate the exploitation of the Non-circularity of radar signal property in a bistatic MIMO radar to improve the performance of joint estimation of direction of arrival (DOA) and direction of departure (DOD) of targets using Combined ESPRIT-RootMUSIC techniques. Simulation results are carried out to illustrate the performance of the proposed approach.

HBT power amplifier with dynamic base biasing for 3G handset applications

In this paper, a performance optimization of a digital signal processing driven and dynamically biased 3G handsets power amplifier technique is proposed, simulated and implemented. This technique uses a new dynamically base biasing heterojunction bipolar transistor which reduces the dc power consumption at low level drive and at the same time compensates the nonlinear distortion at high power drive of the PA in the transmitter of a universal mobile telecommunications system (UMTS) system with a high integrability. With the UMTS system, at low level drive, the dc power reduction is about 60% and at high emission power, the nonlinearity of the PA is corrected to respect the adjacent channel power ratio (ACPR) and error vector magnitude constraints imposed by the UMTS. With our system, the ACPR and efficiency of the power amplifier are improved, respectively, by 5 dB and 8%.