Implementation of high-speed OFDM modems for radio channels with signal fading

The article discusses methods for implementing signal modems with Orthogonal Frequency Division Modulation (OFDM) designed for high-speed transmission of digital signals on radio channels with signal fading, with the duration of signal fading in the radio channel to be hundreds and thousands of times longer than the duration of the transmitted digital signal packets. In such conditions, excessive coding and interleaving do not provide guaranteed transmission of digital information, while OFDM modulation provides high-speed transmission of digital signals over radio channels with signal fading. The article provides calculations of the achievable digital information transmission rate in OFDM modems depending on the duration of signal fading in the radio channel and on the parameters of fast Fourier transform (FFT) processors that are used in OFDM signal modems. It was shown that the transmission rate of digital stream B or the throughput of OFDM modems in radio channels with signal fading increases due to an increase in the number of subcarriers equal to the number of processing points by the FFT processor and the number of positions of the transmitted signal on each subcarrier, and due to a decrease in the duration of signal fading. Notably, the processing time of all points by the FFT processor should be less than the symbol duration on each subcarrier.