D.S. Gagarina1, V.V. Egorov2

1 JSC «Russian Institute of Powerful Radio Engineering» (St. Petersburg, Russia)

2 Saint-Petersburg State University of Aerospace Instrumentation (St. Petersburg, Russia)

1 gagarinadariia@mail.ru, 2 egorovrimr@mail.ru

In modern wireless messaging systems, phase-shift keyed OFDM signals are widely used [1], allowing messages to be transmitted over non-stationary channels in multipath conditions under the influence of narrowband interference without using pilot and training signals. However, the presence of nonlinear elements in a radio transmitting device imposes restrictions on the use of effective types of modulation, including the method of multiplexing with orthogonal frequency division of channels [2]. Nonlinearity is the cause of parasitic distortion of signals and interchannel interference at the output of a radio transmitting device. Designing a radio transmit-ting device with high linearity characteristics is often an expensive project, therefore a more promising method is adaptive pre-correction of signals, often called linearization of the characteristics of a radio transmitting device. [3,4]. Usually, pre-correction devices are implemented as a separate element of a radio transmitter and the algorithm of its operation does not depend on the type of information signal. In this case, the pre-correction operation is performed depending on the transmitted information with different quality [5]. In this paper, the pre-correction problem is considered for each elementary signal. The pre-correction operation should be performed at the stage of synthesis of each elementary signal by the modulator using digital signal processing methods.

In order to evaluate the efficiency of the developed pre-correction method, a computational experiment was carried out.

During the computational experiment, information symbols are formed on a machine time scale, samples of the simulated OFDM signals are calculated at the corresponding moments in time, the process of passing the OFDM signal through a nonlinear element and frequency-selective circuits is simulated, and the linear integral equation and incomplete cubic equation are then solved using J. Cardano's formulas.

The results obtained show that the pre-correction algorithm based on solving the incomplete cubic equation is more efficient, i.e. it allows reducing the root-mean-square value of the phase deviation from the specified values by 2-3 times. This allows the use of signals with relative phase shift keying of large positionalities.

Gagarina D.S., Egorov V.V. Precorrection of nonlinear distortions of a radio transmitting device. Achievements of modern radioelectronics. 2025. V. 79. № 8. P. 21–29. DOI: https://doi.org/10.18127/j20700784-202508-02 [in Russian]

1. Bakulin M.G., Kreyndelin V.B., Shloma A.M., Shumov A.P. Tekhnologiya OFDM. Goryachaya liniya - Telekom. 2022. [in Russian]
2. Guk I.I. Fazovaya kompensatsiya nelineynykh iskazheniy na vykhode usilitelya moshchnosti. Tekhnika sredstv svyazi. 2018. № 7. S. 90–105. [in Russian]
3. Bryukhanov Yu.A., Krasavin K.A. Nelineynye iskazheniya signalov v moshchnykh vykhodnykh usilitelyakh. Radiotekhnika. 2019. № 8 (11). S. 28–37. [in Russian]
4. Tikhonov V.Yu., Shinakov Yu.S., Timoshenko A.S., Bakhtin A.A. Tsifrovaya obrabotka nelineynykh iskazheniy signala v programmno-opredelyaemoy radiosisteme (SDR). Tsifrovaya obrabotka signalov. 2020. № 1. S. 3–8. [in Russian]
5. Makoviy V.A., Evseev M.A. Spektral'nyy metod sinteza korrektiruyushchikh nelineynykh elementov dlya peredayushchikh traktov. Radiotekhnika. 2016. № 5. S. 67–75. [in Russian]
6. Morgan D.R., Ma Z., Kim J. A generalized memory polynomial model for digital predistortion of RF power amplifiers. IEEE Trans. On signal processing: 2006. V. 54. № 10. P. 3852–3860.
7. Yagola A.G., Yanfey V., Stepanova I.E., Titarenko V.N. Obratnye zadachi i metody ikh resheniya. Prilozheniya k geofizike. M.: BINOM. Laboratoriya znaniy. 2017. [in Russian]
8. Gakhov F.D., Cherskiy Yu.I. Uravneniya tipa svertki. M: Nauka. 1978. [in Russian]
9. Asxabov S.N. Nelineynye uravneniya tipa svertki. M.: Fizmatlit. 2009. [in Russian]
10. Lebedev V.I. Funktsional'nyy analiz i vychislitel'naya matematika. M.: Fizmatlit. 2000. [in Russian]
11. Chen H.-H., Lin C.-H., Huang P.-C., Chen T. Join polynomial and look-up-table predistortion power amplifier linearization. IEEE. Journal of selected topics in signal processing. June 2009. V. 3. № 3.
12. Gonorovskiy I.S, Demin M.P. Radiotekhnicheskie tsepi i signaly. M.: Radio i svyaz'. 1994. [in Russian]
13. Egorov V.V. Adaptivnaya korrektsiya nelineynykh iskazheniy pri sinteze i obrabotke OFDM signalov. Sb. dokladov 18–y Mezhdunar. konf. «Tsifrovaya obrabotka signalov i ee primenenie». 2016. S. 320–323. [in Russian]
14. Golovanov N.N. Geometricheskoe modelirovanie. M.: Fizmatlit. 2002. [in Russian]
15. Makoviy V.A., Evseev M.A. Raschet parametrov nelineynosti v tsifro-analogovykh traktakh diapazona DKMV. Teoriya i tekhnika radiosvyazi. 2013. № 4. S. 17–25. [in Russian]
16. Breysuell R. Preobrazovanie Khartli. M.: Mir. 1990. [in Russian]
17. Egorov V.V., Maslakov M.L. Ispol'zovanie preobrazovaniya Khartli dlya resheniya integral'nogo uravneniya tipa svertki. Tsifrovaya obrabotka signalov. 2014. № 2. S. 2–6. [in Russian]