Research On Beam Forming Of Virtual Antenna Array Based On Higher-Order Cumulants

As the development of science and technology, adaptive array antenna is more and morewidely applied in areas such as communications, radar and navigation. Adaptive array antennais developing to smart antenna. There are many advantages in smart antenna, but the numberof degrees of freedom is still less than the number of elements. More elements are neededbecause of the worse electromagnetic environment. However, the elements of array arealways limited. In recent years, virtual antenna is developing on the basis of the smart antennain order to increase the degree of freedom of the adaptive array antenna to suppress moreinterference, or to suppress the same number of interference with less elements of arrayantenna. The virtual antenna technology is always applied in DOA estimation. This thesisresearches on the application of virtual antenna that based on higher-order cumulants in beamforming.Firstly, the uniform linear array antenna modeling is described and conventional adaptivebeam forming method for LCMV. Several methods of virtual array formation are compared.The method based on higher-order cumulants is used at last. Finally, beam forming of virtualantenna based on fourth-order cumulants is proposed.Virtual elements are formed by the beam forming method of virtual antenna based onfourth-order cumulants, which increases the number of degrees of freedom of antenna. Moreinterference is suppressed. This method is better than conventional ones when the number ofinterference is less than the number of degrees of freedom of antenna. If the number ofinterference is more than the number of degrees of freedom of antenna, the method based onfourth-order cumulants still works but the conventional ones. Compared with the methodbased on fourth-order moments, the method based on fourth-order cumulants is blind toGaussian noise.