Orthogonal Frequency Division Multiplexing –OFDM) multiplexing technology is quite promising in wireless communication systems. Simultaneous use of multiple subcarriers allows for a relatively high information transfer rate. The use of mathematical models of discrete wavelet transformations instead of the fast Fourier transform (hereinafter FFT), allows you to increase the speed of signal processing by using modular codes of residue classes (hereinafter MKV). At the same time, these codes can be used to increase the noise immunity of systems with OFDM. It is known that block turbo codes (hereinafter referred to as TC) are widely used to combat packets of errors that occur when transmitting signals over a communication channel. The article presents a developed method for constructing modular turbocodes based on a system of residual classes (hereinafter MTKSOC). Obviously, the use of MTCS entails changes in the structure of the system with OFDM. Therefore, the development of a method for constructing a modular turbo code of SOC and a structural model of an interference-resistant system with OFDM using MTXOC is an urgent task. The purpose of the article is to increase the level of noise immunity of systems with OFDM, using wavelet transformations implemented in MKV instead of FFT, through the use of modular turbo code SOC.

Keywords: modular codes of residue classes, residual class system, modular turbo code of residual class system, error correction algorithm, structural model, multiplexing, orthogonal frequency division of channels

To improve the efficiency of low-orbit satellite Internet systems (LOSIS) and ensure high apeed of data exchange, systems supporting orthogonal frequency-division multiplexing (OFDM) technology are widely used. The use of OFDM methods makes it possible to expand the bandwidth of the radio channel based on the increase in spectral efficiency. In order to do this, OFDM systems use orthogonal signal transformation based on fast Fourier transformation (FFT). To reduce the time spent on signal processing, the article proposes to use discrete wavelet transformations of signals (DWT) implemented in modular residue classes codes (MRCC). The scientific novelty of the work lies in the fact that based on the integration of methods for constructing discrete wavelet transforms and methods for developing modular codes, mathematical models of DWT implemented in the MRCC will be created, the use of which will reduce the execution time of orthogonal signal processing in OFDM systems. This result will be achieved by parallelizing arithmetic operations on the modules of the modular code. At the same time, the use of low-bit operands makes it possible to switch from performing multiplication, addition, and subtraction operations in the MRCC to retrieving data from LUT tables. Thus, the development of mathematical models of discrete wavelet transformations implemented in modular codes of residue classes is an urgent task.

Keywords: OFDM systems, discrete wavelet transformation, parallel coding, modular residue classes code