P.V. Luferchik1, А.V. Luferchik2, R.G. Galeev3, Е.V. Bogatyrev4, P.V. Shtro5

1-5 JSC SPE «Radiosvyaz» (Krasnoyarsk, Russia)

Tropospheric radio communication is based on the usage of the electromagnetic energy re-emission in an electrically inhomogeneous troposphere during the propagation of radio waves in it. The electrical inhomogeneity of the troposphere (the inhomogeneity of its dielectric permittivity) is due to random local changes in temperature, pressure and humidity, as well as a regular decrease in these values with increasing altitude. The re-emission of energy occurs in the area of the intersection of the radiation patterns transmitting and receiving antennas. When transmitting data, intersymbol interference may occur caused by the presence of multipath propagation and frequency-selective fading in the tropospheric radio channel, which can significantly reduce the energy efficiency of communication systems. The usage of the OFDM (Orthogonal frequency-division multiplexing) method can be the solution of this problem. This approach makes it possible to reduce the influence of frequency-selective fading and intersymbol interference, and increases the energy efficiency of the communication system.

This paper presents the main features of the OFDM operating mode, which allow to increase the radio line energy potential, effectively combat frequency-selective fading and intersymbol interference in the tropospheric radio channel.

As a result of the work and modeling, methods for increasing the energy efficiency of the communication system in the tropospheric channel were developed. Various peak factor reduction algorithms have been simulated and two PAPR reduction algorithms have been implemented. Due to the usage of a large number of OFDM subcarriers the best algorithms for usage in the tropospheric channel are
Active Constellation Extension (ACE) and Tone Reservation (TR), which are used in cascades and reduce the peak factor by 4,8 dB. An upgraded RLSm digital pre-order input algorithm was selected and implemented to increase the linearity of the transmission path. It allowed to reduce the magnitude of the error vector modulus (EVM) by 13,5 dB, as well as to increase the modulation/error ratio (MER) by 13,6 dB. The received results will significantly increase the OFDM energy efficiency, lead to stable communication in the non-stationary tropospheric channel and increase throughput.

Luferchik P.V., Luferchik А.V., Galeev R.G., Bogatyrev Е.V., Shtro P.V. Improvement of the energy characteristics of a tropospheric communication modem. Achievements of modern radioelectronics. 2022. V. 76. № 5. P. 50–54. DOI: https://doi.org/10.18127/j20700784-202205-04 [in Russian]

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