Scientific and Technical Journal

ELECTROTECHNIC AND COMPUTER SYSTEMS

ISSN Print 2221-3937
ISSN Online 2221-3805
FEATURES OF THE OFTDM-TECHNOLOGY OF DATA TRANSMISSION
Abstract:

The features of OFDM/QAM and OFDM/OQAM (OFTDM) modulation, their strengths and weaknesses and areas of their practical application are considered. The basic approaches and methods used in digital communication systems to suppress the intersymbol and interchannel interference in terms of additive interference are presented. A development and application of OFTDM information transfer technology based on generalized orthogonal basis of Weyl-Heisenberg that minimizes the level of mutual influence of subcarrier channels both in frequency and in the time domain are offered. In calculations the discrete Hartley transform is used instead of the discrete Fourier transform.

The study showed that the use of OFTDM technology instead of OFDM technology in channels with variable time division allows to:

– increase the spectral and energy efficiency of system by organizing intersymboltime consolidations. Another advantage is the good location of base functions in the frequency domain. Spectrum of OFTDM symbol has rapidly falling tails so low external bandpass emission, which significantly reduces requirements for filtering the output signal transmitter and reduces the required number of protective "zero" subcarriers within the frequency domain. Freed subcarriers can be used for the transmission of useful information;

– significantly reduce external bandpass emission, and thereby to ease the requirements for output filter of the transmitter and for the protective interval within frequency domain. Another advantage is the system stability (robustness) to intersymbol and interchannel interference within each OFTDM character.

Obtained results showed that OFTDM technology with the Hartley transformation core can speed up data transmission rate twice and reduce the number of hardware multipliers and adders in the modulator and demodulator.

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References

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