Adaptive broadband beamformer for nonuniform linear array based on second order cone programming

Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of minimizing the beamformer＇s output power while keeping the distortionless response （DR） in the direction of desired signal and keeping the constant beamwidth （CB） with the prescribed sidelobe level over the whole operating band. This kind of beamforming problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our beamformer.

SRV constraint based FIB design for wideband linear array

Frequency-invariant beamformer （FIB） design is a key issue in wideband array signal processing. To use commonly wideband linear array with tapped delay line （TDL） structure and complex weights, the FIB design is provided according to the rule of minimizing the sidelobe level of the beampattern at the reference frequency while keeping the distortionless response constraint in the mainlobe direction at the reference frequency, the norm constraint of the weight vector and the amplitude constraint of the averaged spatial response variation （SRV）. This kind of beamformer design problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our FIB design method for the wideband linear array with TDL structure and complex weights.

Second order duality for multiobjective programming with cone constraints

We focus on second order duality for a class of multiobjective programming problem subject to cone constraints. Four types of second order duality models are formulated. Weak and strong duality theorems are established in terms of the generalized convexity, respectively. Converse duality theorems, essential parts of duality theory, are presented under appropriate assumptions. Moreover, some deficiencies in the work of Ahmad and Agarwal(2010) are discussed.

Side-lobe constrained beamforming under virtual expansion of L-shaped array

To reduce the side-lobe level of L-shaped expansion array and improve the output signal to interference and noise ratio(SINR),the algorithm of side-lobe constraint based on minimum variance distortionless response(MVDR-SC)is proposed.Firstly,the approach of mixing diagonal loading and Mailloux-Zatman(DLMZ)is used to taper the covariance matrix of the expansion array.Then,the second order cone programming(SOCP)obtained by constructing a new matrix is used to control the beam side-lobe.Finally,the new adaptive weight numbers are constructed by adjusting the proportion between DLMZ and SOCP.Simulation results show that the MVDR-SC algorithm can effectively reduce the side-lobe of beamforming under the L-shaped expansion array and obtain a larger output SINR.At the same time,it has good robustness to the mutual coupling error.