A.S. Merkutov1

1 Vladimir State University named after Alexander Grigorievich and Nikolai Grigorievich Stoletovs (Vladimir, Russia)
1 merkutov@yandex.ru

The need to ensure high-speed information transmission over wireless digital communication channels using high-order quadrature modulation in conditions of limited frequency resources, complex electromagnetic environment, multipath signal propagation and strong intersymbol interference (ISI) is an important task. Therefore, in this paper, various methods for creating 1024-QAM modulated signal demodulators based on the use of adaptive equalizers, which were implemented and studied in CAD under conditions of external influences (additive white Gaussian noise, carrier frequency offsets, etc.) at various settings of equalizer parameters are considered. Scalable models of signal generation and detection units with 1024-QAM and higher modulation order have been developed for modeling information transmission channels with multi-position quadrature modulation. Demodulator models have been developed using an equalizer based on a known training sequence of symbols and a «blind» equalizer adapted to a random stream of symbols following on input of receiver. The boundary values of the permissible relative frequency adjustments of the modulated signal for both types of equalizers are obtained, as well as optimal weighting coefficients of the adaptation error for a given threshold value of the bit error rate and power signal-noise ratio. The results of the evaluation of the effect of the adaptation interval on the convergence of the iterative process under of carrier frequency offset presence on the input of the demodulator are obtained. The results of the study can be used in the design of digital signal demodulators with multi-position quadrature modulation for subsequent implementation in the FPGA base or ASIC technology.

Merkutov A.S. Simulation of 1024-QAM signals receivers based on adaptive equalizers. Dynamics of complex systems. 2025. V. 19. № 2. P. 21–29. DOI: https://doi.org/10.18127/j19997493-202502-04 [in Russian]

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