Analysis and Synthetic Model of Adaptive Beamforming for Smart Antenna Systems in Wireless Communication

摘要

Adaptive beamforming is one of the radio resource controlling systems and define as a process by which an adaptive spatial signal processing are performed on array of antennas. By the addition of the signals weights constructively in the preferred direction of signal, adaptive beamforming technique creates radiation pattern on antenna array thereby nulling pattern in the unwanted direction that is interference. These arrays are antennas in the smart antenna context. Adaptive beamforming are normally used to achieve spatial selectivity at transmitting and receiving ends. In this research work, adaptive beamforming algorithms techniques (Least Mean Square and Recursive Least Square) are considered for the smart antennas. Uniform array of isotropic elements M (10, 15, and 20) are considered having their coordinate system in the direction of y. The spacing of the antenna elements are varied at d (0.5λ, 0.6λ and 2λ). The angles at which the grating lobe appears, steering angle, and the antenna element's effect spacing on beamforming has been examined. The following are the observation as the antenna element spacing are increasing: (ⅰ) narrower main lobe, (ⅱ) grating lobes, (ⅲ) reduction in beamwidth (thus making the array more directional), and (iv) reduction in sidelobe level, thus improving beamforming. It has been also observed that there is no grating lobe when d/λ = 0.5, which we have considered as the optimal design spacing for the array antenna elements in the smart antenna..