LEAST SQUARED CONSTANT MODULUS FOR OPTIMIZED ERROR ESTIMATION IN BEAMFORMING UNIT

Subject Area: Telecommunication Engineering

Radio frequency (RF) management is very important in communication system considering the limited availability of spectrum. In modern technology such as WiFi and 5G, beamforming found relevance in the management of radio frequency for optimization of signal to noise ratio thereby improving network capacity, spectral efficiency, and coverage range. In this paper, beamforming technology was studied and the results of the behavior of the error signal generating unit were observed. Blind adaptive algorithm was considered over non-blind adaptive algorithm to control the output of the combiner in the beamforming structure and also helped to focus the beam to the desired direction.Thus, utilizing the narrow lobe with maximum power and rejecting side lobes which it sees as interference, thereby supported maximum transmission. Equalizer filters which are made up of finite response filters were used to weigh the signals impinging on the elements of the receiver antenna. The output of the equalizer filters were fed directly to the combiner which used a diversity combining approach based on the principle of maximum combining ratio to combined the signal from each antenna array logically to produce improved signal strength. The output of the combiner and desired signal from the decision feedback structure were used to update the error signal in the signal processing unit for weights adaptation to changes in the radio environment based on the angle of arrival. Least Square Constant Modulus Algorithm (LSCMA) was employed for the estimation of error signal in the beamforming unit. The proposed model of the LSCMA was simulated and compared with the conventional constant modulus. From the result of the simulation models it showed that LSCMA minimized error better than the conventional Constant Modulus Algorithm (CMA). For conventional CMA, error increases with an increase in signal power received while with LSCMA, error decreases with an increase in signal power received. A suitable adaptive algorithm for the beamforming unit of the system was proposed and represented in a flow chart.