Research On Adaptive Beamforming Algorithm For MIMO Smart Antenna System

In order to alleviate the problem of the growing wireless communications and insufficient spectrum resources, this paper combines smart antenna technology and MIMO technology, knowed as MIMO smart antenna. MIMO smart antenna is a system using multiple smart antennas both at the base station and mobile station.Beamforming is the core technology of smart antenna, the key lies in the choice of adaptive beamforming algorithms. This paper divided the adaptive beamforming algorithm into non-blind adaptive algorithm and blind adaptive algorithm, respectively study and then comparative anlysis these algorithms. Least squares constant modulus algorithm (LS-CMA) is drived based on a blind algorithm for constant modulus algorithm (CMA); Root MUSIC algorithm is proposed based on multiple signal classification (MUSIC) algorithm. In this paper, proposes matrix normalized least mean square (MI-NLMS) algorithm that based on non-blind algorithms for the minimum mean square (LMS) algorithm and the sample matrix inversion (SMI) algorithm. By simulation, demonstrate these improved algorithms have a significant improvement on supressing inferences, enhancing the useful signals and the beamforming convergence speed.