METHOD FOR PARALLEL MULTI-FREQUENCY TRANSMISSION OF DIGITAL INFORMATION USING COMBINED MULTI-POSITION FREQUENCY AND PHASE MODULATION IN FREQUENCY SUBCHANNELS Russian patent published in 2016 - IPC H04L27/32 

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to digital communication engineering and can be used for the multi-frequency transmission of digital information via communication links. The transmission method includes the combination of digital multi-frequency and multi-position phase modulation of OFDM subcarriers, the number of which is equal to N, divided for modulation into clusters (groups) of L subcarriers. In each cluster, multi-frequency modulation symbols are transmitted by selecting R from L subcarriers, of which P are then phase-modulated, while R-P subcarriers remain unmodulated. At the receiving side, after the selection of quadrature subcarrier components in the OFDM circuit, demodulation is performed in two steps: first, multi-frequency modulation symbols are incoherently demodulated by determining R subcarriers; at the second step, using reference oscillations generated from the quadrature components of the modulated R-P subcarriers, P phase-modulated subcarriers are coherently demodulated.

EFFECT: high spectral efficiency and noise-immunity of the methods for the multi-frequency transmission of digital information, which do not require the inclusion, in the transmitted signal, of special training signals or pilot tones for channel state estimation.

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