Utilization of AGC circuits in signal processing algorithms in adaptive antenna arrays

DOI: 10.31673/2412-9070.2019.065257

Abstract

With the development of telecommunications systems and technologies, adaptive antenna arrays are increasingly used, especially in 4G and 5G mobile systems. The authors have developed a gradient algorithm for the adaptive antenna array, which does not require the formation of a reference signal. Gradient methods of adaptation in antenna arrays are considered and their efficiency is analyzed with respect to the novel algorithm developed previously. It is proven that for a changing signal environment, when powers of noise signals change substantially, wide variations in array performance with the proposed algorithm may take place, ranging from loss of ability to cancel noise to very slow convergence. It is offered to introduce automatic gain control (AGC) circuits into the adaptive control loops of the designed algorithm to improve the performance of the algorithm in the dynamic changes of the interference environment without constantly updating the value of the adaptation step. This technique is shown to mitigate the effects of varying noise intensity without compromising array performance. Computer simulation of adaptive antenna arrays based on the algorithm with the AGC circuits in different noise environments is carried out. A useful signal / interference ratio, known as SNR, at the output of the lattice was used to evaluate the tuning process. For the simulation of noise processes, uncorrelated readings distributed according to normal law were used. The interference signal strength was measured in terms of the relative noise power. The potential possible signal-to-noise ratio, calculated from the ideal correlation matrix by known formulas for these simulation conditions, is approximately 29.46 dB. Simulation of the developed algorithm confirmed its operability and effectiveness High performance of the improved gradient algorithm is confirmed in challenging interference conditions.

Keywords: mobile telecommunication systems; adaptive antenna arrays; gradient adaptation algorithms; computer simulation; signal-to-interference ratio; automatic gain control circuits.

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