"JOURNAL OF RADIO ELECTRONICS" (Zhurnal Radioelektroniki ISSN 1684-1719, N 6, 2017

contents             full textpdf   

Results of simulation of probability of QAM and APSK signals transmission errors caused by nonlinearity of Q-band transmitter


A. M. Ripak 1,2, M. K. Lebedev 1,2, V. B. Khaikin 1,2

1 Special Astrophysical Observatory of Russian Academy of Sciences, Sankt-Petersburg Branch, Pulkovskoe shosse 65, Sankt-Petersburg 196140, Russia

2 Scientific-Production Firm "Aisberg-NT" Ligovskiy prospekt 195, Sankt-Petersburg 192007, Russia


The paper is received on May 30, 2017


Abstract. The multichannel QAM and APSK signal transmission in the Q band is considered. The analysis has been performed of the mutual interference of channels when passing QAM and APSK signals through the amplifier with a nonlinear transfer characteristic. We consider two mechanisms of the intermodulation distortion effect on the probability of the error in symbol transmission, namely effect of in-phase intermodulation components on the signal in the given channel, and effect of additive in power components caused by the interaction between two or three channels other than the given one. In order to estimate the effect of the second mechanism the central limit theorem was used. We obtained a top estimate for the probability of the signal transfer error arising due the mutual channels interference caused by the amplifier nonlinearity as a function of gain compression level, modulation index, and number of channels. The OIP3 value was taken as a parameter that affects the probability of the erroneous signal transfer. In order to validate the results obtained, the Simulink model of the multichannel QAM signal transfer was built and the results of the modeling had been studied. The model accounts for three mechanisms of interference due to the power amplifier nonlinearity. The first one is the inter­modulation mechanism, the second one is the signal constellation distortion caused by the difference in the amplification for the constellation points with different amplitudes, and the third one is the mismatch of filters in the transmitter and the receiver as the transmitting power increases, leading to the increase in inter­symbol interference and the constellation points “blur”. The latter two mechanisms manifest themselves in both multichannel and single-channel systems. In this work the intermodulation mechanism is studied in detail. All the calculations performed for the power amplifier IC MAAP-010512 manufactured by MACOM with P1dB = 27 dBm and POIP3 = 38 dBm and the input signal power levels corresp­onding to the gain compression of 0.5–1 dB.

Key words: Q band, transmitter, QAM, APSK, intermodulation, error probability.



1. Trofimov A. N. Metody peredachi diskretnykh soobshchenij. [Methods of discrete messages transmission]. Lecture notes (feb. 2004). St. Petersburg, St. Petersburg State University of Aerospace Instrumentation. 2001–2004 (in Russian).

2. Levin B. R. Teoreticheskie osnovy statisticheskoj radiotekhniki [Theory fundamentals of statistical radiotechnics]. Moscow, Radio i svyaz’ Publ. 1989, 656 p. (in Russian).

3. Chorti A., Brookes M. On the Effects of Memoryless Nonlinearities on M-QAM and DQPSK OFDM Signals. IEEE Transactions on Microwave Theory and Techniques, Aug. 2006, vol. 54, no. 8, pp. 3301-3315.

4. Proakis J. Digital communications. McGraw-Hill, 1995.


For citation:

A. M. Ripak, M. K. Lebedev, V. B. Khaikin. Results of simulation of probability of QAM and APSK signals transmission errors caused by nonlinearity of Q-band transmitter. Zhurnal Radioelektroniki - Journal of Radio Electronics, 2017, No. 6. Available at http://jre.cplire.ru/jre/jun17/2/text.pdf. (In Russian)