A.S. Ovsyannikova1, S.B. Makarov2, S.V. Zavjalov3, S.V. Volvenko4

1-4 Peter The Great St. Petersburg Polytechnic University (Saint-Petersburg, Russia)

Formulation of the problem. It is possible to achieve specific data rates equal to 10-15 (bps)/Hz with minimal energy losses (no more than 3-4 dB) by using optimal spectrally efficient signals with controlled intersymbol interference. This will allow data transfer at a speed 3-4 times higher than the Nyquist barrier.

The goal is to obtain quantitative results of approaching the Shannon boundaries of the spectral and energy efficiency of an information system that uses single-frequency M-ary signals optimized according to the criterion of maximum band energy concentration with increased signal constellation sizes, providing minimal energy losses for coherent element-by-element detection.

Results. The use of optimal signals obtained in accordance with the criterion of maximum energy concentration in the occupied frequency band allows obtaining high spectral and energy efficiency of the information system. It is shown that the spectral efficiency of 11.4 (bit/sec)/Hz is achieved by using optimal signals with quadrature amplitude modulation and the volume of the channel alphabet M=1024. It is shown that the use of new spectrally efficient optimal signals provides a significant approximation of the information system to the Shannon boundaries. With signals obtained as a result of using the criterion of 85% energy concentration in the frequency band, it is shown that the spectral efficiency of 11.4 (bit/sec)/Hz is inferior to the Shannon boundary by only 2% at Eb/N0=24.5 dB for signals with cross-correlation coefficient K0=0.01. When synthesizing the shape of the optimal amplitude pulses, depending on the choice of the signal energy concentration criterion in the occupied frequency band at different values of the cross-correlation coefficient K0=0.01 and K0=0.1, it is shown that the change in the shape of the optimal amplitude pulse depends very little on the choice of the band energy concentration criterion (99% or 85%).

Practical significance. The proposed optimal signals can be used in the modification of digital broadcasting and television in the direction of increasing the data rate without increasing the bandwidth of the occupied frequencies.

Ovsyannikova A.S., Makarov S.B., Zavjalov S.V., Volvenko S.V. Estimation of information system approximation to the Shannon limit by applying signals optimized according to the criterion of maximum band energy concentration. Radiotekhnika. 2023. V. 87. № 1.
P. 5−22. DOI: https://doi.org/10.18127/j00338486-202301-01 (In Russian)

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