V.G. Kartashevsky - Dr. Sc. (Eng.), Professor, Dean of Faculty of Telecommunication and Radiotechnik, Head of Department of Multiservices Networks and Information Security, Volga State University of Telecommunications and Informatics (Samara) E-mail: kartash@psati.ru E.S. Semenov - Ph. D. (Eng.), Associate Professor, Head of Department of Telecommunication Systems, Volgograd State University E-mail: essemenov@mail.ru A.A. Filimonov - Undergraduate, Volga State University of Telecommunications and Informatics (Samara) E-mail: Alfhero@gmail.com

In article the problem of processing of signals of orthogonal frequency multiplexing (OFDM) in channels with dispersion is considered. In previous studies, it is shown that there is an alternative approach to solving the problems of struggle against time dispersion in the channel, based not on the introduction of protective intervals between the transmitted OFDM-symbols, but on the use of optimal methods of processing signals in serial (single-channel) systems in channels with memory. In particular, it is proposed to use the algorithm of «reception a whole with elementwise decision» by changing the problem of distinguishing on assessment task. This approach can save up to 20% of the bandwidth of the communication channel, which, as we know, can be exchanged for the accuracy of the transmitted messages. To implement any optimal processing algorithm in place of receiving required information about the properties currently in use, the communication channel. The article describes the properties of the channel impulse response estimation is performed on a periodically transmitted pilot signals, an information content which is known in the receiving place. Estimation of the impulse response results in to the need to solve the inverse problem. The inverse problem solution is based on the method of Tikhonov regularization, which, according to the authors, allows to get the best quality «Instant» impulse response estimates. The analysis of the mean squared error estimation for regularized and maximum likelihood estimates when receiving for a background additive Gaussian noise. Modeling of the above algorithm demodulate the OFDM symbol with QAM modulation using regularized channel impulse response es-timates showed its high noise immunity in a wide range of signal-to-noise ratio.

 

1. Kartashevskijj V.G. Obrabotka prostranstvenno-vremennykh signalov v kanalakh s pamjatju. M.: Radio i svjaz. 2000. 272 s.
2. Kartashevskijj V.G., Belskijj K.A., Slipenchuk K.S. Priem signalov OFDM v kanalakh s rassejaniem // Radiotekhnika. 2015. № 2. S62−68.
3. Kartashevskijj V.G., Konjaeva O.S., Semenov E.S. Priem «v celom» dlja sistemy MIMO v kanale s pamjatju // Uspekhi sovremennojj radioehlektroniki. 2015. № 11. S. 49−53.
4. Kartashevskijj V.G., Belskijj K.A., Filimonov A.A. Priem signalov OFDM v sisteme MIMO v kanalakh s pamjatju // Radiotekhnika. 2016. № 2. S. 91−95.
5. Burdin V.A., Kartashevsky V.G., Grigorov I.V. Based on reception in general with bit-by-bit decision-making algorithm for signal processing in fiber optic telecommunication systems // Proc. of SPIE V. 9807. Optical Technologies for Telecommunications 2015. 10 p.
6. Kartashevskijj V.G., Mishin D.V. Priem kodirovannykh signalov v kanalakh s pamjatju. M.: Radio i svjaz. 2004. 239 s.
7. Tikhonov A.N., Arsenin V.JA. Metody reshenija nekorrektnykh zadach. M.: Nauka. 1979. 288 s.
8. Volkov L.N., Nemirovskijj M.S., SHinakov JU.S. Sistemy cifrovojj radiosvjazi. M.: EHko-Trendz. 2005. 392 s.