Implementation of the adaptive beamforming algorithm on FPGA

The paper regards the field-programmable gate array (FPGA) implementation of a beamforming algorithm in adaptive antenna arrays. The relevance of the research is due to the need to improve the noise robustness of signal reception in radio engineering systems. The gradient algorithm was chosen as a beamforming algorithm by the criterion of the normalized least mean square error criterion (NLMS), which has the lowest computational complexity, and its use of a variable adaptation step helps to ensure the convergence of the algorithm in terms of a priori unknown power of the input signal. This paper gives a mathematical description of the adaptive signal processing procedures and formulas for calculating the optimal weight vector that provide the best approximation of the input signal to the reference signal. Approximate methods that provide a practical realization of the optimal signal processing based on iterative algorithms in the form of the normalized minimum mean square error algorithm are considered. Examples of the antenna array directional diagram synthesis facilitating adaptive signal processing, implemented on FPGA, under different signal-interference conditions are presented. An acceptable agreement between theoretical and experimental data was obtained for all implementation cases.

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